1

Possible indirect evidence for axion-like particles from far away AGN

Alessandro De AngelisINFN INAF and Udine University

bull Photon propagationbull Observation of distant AGNbull Axion-Like Particles amp the DaRMa

scenariobull Conclusions

The work on axions has been done in collaboration with M Roncadelli O Mansutti and M Persic

2

Intergalactic absorption of VHE photons

Cross section maximized for infraredoptical photons

(Extragalactic Background Light)

(Heitler 1960)

3

What is the attenuation

bull

bull = cos

bull n (z) is the spectral

energy density of background

photons lt=EBL

)(emobs )()( zEeEzE

MAGIC Science 2008

4

(An approximation)

bull Neglecting evolutionary effects for simplicity

1

Coppi amp Aharonian ApJ 1997

)(emobs )()(

1

)()(

E

D

eEDE

E

DDE

5

Consequencesbull Since becomes lt RHubble for E gt 100 GeV

ndash The observed flux should be exponentially suppressed at large distances so that very far-away sources should become invisible as energy increases

ndash The observed flux should be exponentially suppressed at VHE so that the SED should be steeper than the emitted one

6

The VHE Universe far awayhellip

35 SourceshellipPKS 0447-439 z=020 HESS 20091ES 1011+496 z=021 MAGIC 20071ES 0414+009 z=029 HESS amp Fermi 2009S5 0716+71 z=031plusmn008 MAGIC 20091ES 0502+675 z=034 VERITAS 20093C 66A z=044 VERITAS 2009 3C 279 z=054 MAGIC 2008

7

The distant quasar 3C 279

bull Flat spectrum radio quasar at z=054bull Very bright and strongly variable

ndash Brightest EGRET AGNndash Gamma-ray flares in 1991 and 1996 Fast time variation (~ 6hr in 1996 flare)

bull MAGIC observationsndash 10 h between Jan-April 2006

ndash clear detection on 23rd Feb at 62σ

First FSRQ in TeV -rays

Major jump in redshift

8

The distant quasar 3C 279 is back

bull New observations after optical outburst in Jan 2007

New flare detected

Most distant object ever detected at VHE - two flares (Feb 2006 and Jan 2007)

Emission harder than expected -gt constrains the EBL universe more transparent to -rays than expected

9

Implications on Extragalactic Background Light

e-e+

EBL

VHE

blazarIACT

10

bull At ~05 TeV flux attenuated by 2 orders of magnitudebull The measurement of spectral features permits to constrain EBL models

ndash Power law Γ = 41 plusmn 07 measured up to 05 TeV Spectrum sensitive to 02 to 2 μm

ndash Assume minimum reasonable index Γem = 15

bull Upper limit close to lower limit from galaxy countbull Explanations go

ndash from standard ones

bull very hard emission mechanisms with intrinsic slope lt 15 (Stecker 2008)

bull Very low EBL

ndash to possible evidence for new physics

bull Oscillation to a particle traveling unimpeded

rarr X rarr

Could it be seen

11

Oscillation to an Axion-Like Particle

ndash Oscillation during the propagation DA Roncadelli amp Mansutti [DARMa] PLB2008 PRD2008

ndash Conversion at the emitter (Hooper et al PRD2008)

ndash Mixed mechanisms (Sanchez-Condersquo et al PRD 2009)

ndash hellip

BEaM

Ptrans

1

12

Phenomenology of the oscillations

bull Photon-ALP oscillations are similar to neutrino oscillations but external B is needed

bull Bounds on the parameters M and m ndash CAST amp astrophysical arguments

M gt 114 1010 GeV for m lt 002 eV

ndash Energetics of SN 1987a

M gt 1011 GeV for m lt 10-10 GeV model dependent

13

(DA FARE) Which EBL First analysis of 3C279 EBL model by Kneiske et al 2004

To be updated including Franceschini et al 2008

14

DARMa Intergalactic magnetic fields

Their morphology is poorly known It is supposed that they have a domain-like structure with

bull strength ~ 05 nG bull coherence length ~ 10 Mpc bull random orientation in each domain

NB - Picture consistent with first AUGER data

strength 03 ndash 09 nG for coherence length 1 ndash 10 Mpc

(DA Persic amp Roncadelli MPLA 2008)

15

Hooper amp Serpico (DA FARE)

16

Sanchez-Condersquo et al (DA FARE)

17

Experimental input from more sources at high z MAGIC S5 0716+714

bull After trigger MAGIC observed 26h April 28 Swift reports flux about 50 larger

than that observed in 2007

Apr 29 ATel 1500 MAGIC reports 68 discovery Apr 23-25 F(gt400 GeV) asymp25 Crab

bull 3rd low-peaked VHE blazar after BL Lac amp W comae

bull Host galaxy detected Z=031+-008 =gt 3rd farthest VHE emitter for which the spectral index has been measured

S5 0716+714Trigger in April

2008

Clear signal 68σNew

discoveryarXiv09072386

18

Deformation of the SED

PKS 0447-439 z=020 HESS 20091ES 1011+496 z=021 MAGIC 20071ES 0414+009 z=029 HESS amp Fermi 2009S5 0716+71 z=031plusmn008 MAGIC 20091ES 0502+675 z=034 VERITAS 20093C 66A z=044 VERITAS 2009 3C 279 z=054 MAGIC 2008

hellipand more new sources are coming into the game (VERITAS HESS MAGIC)

19

Other possible explanationsrelated to new physics

bull Kifune 2001 Violation of the Lorentz invariance

bull We should keep in mind thatndash Extraordinary claims require extraordinary evidence

bull New Scientist SciAm blognews hellip and then

ndash Claims must be followed upbull What else do we expect

bull Fundamental implications of unexpected findings

bull Are we seeing a part of the same big picture

2

222 1 ss E

EO

E

EEpc

20

Conclusions

bull The existence of a very light ALP predicted by many extensions of the SM naturally explains the observed transparency of the VHE gamma-ray sky

bull As a bonus it explains why only the most distant AGN seem to demand an unconventional emission spectrum

bull The DaRMa prediction in particular concerns the spectral change of observed AGN flux at VHE and becomes observable if the TeV band is carefully probed

bull It can be tested with IACTs with Fermi and with EAS

21

rdquoA textbook example of the merging of

particle physics and astronomy into the

modern field of astroparticle

physicsrdquo

22

BACKUP

23

PROPAGATION OVER ONE DOMAIN

We work in the short-wavelength approximation so

the beam with energy E is formally a 3-level non

relativistic quantum system described by the wave

equation

with

24

and mixing matrix

which in the presence of absorption becomes

with

25

Hence the conversion probability reads

in terms of the propagation matrix We find

that a nonvanishing conversion probability over the

WHOLE range requires

with

26

In the present situation we have

and so the mixing matrix reduces to

Following Csaki et al ICAP 05 (2003) 005 we

get the explicit form of the propagation matrix

27

PROPAGATION OVER MANY DOMAINS

When all domains are considered at once one has to

allow for the randomness of the direction of B in the

n-th domain Let be the direction of B in the n-th

domain with respect to a FIXED fiducial direction for

all domains and denote by the evolution

matrix in the n-th domain

Then the overall beam propagation is described by

28

We evaluate by numerically

computing and iterating the result

times by randomly choosing each time

We repeat this procedure 5000 times and next

average all these realizations of the propagation

process over all random angles So the PHYSICAL

propagation matrix of the beam is

29

Assuming that the initial state of the beam is

unpolarized and fully made of photons the initial

beam state is

So we finally get

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al

2

Intergalactic absorption of VHE photons

Cross section maximized for infraredoptical photons

(Extragalactic Background Light)

(Heitler 1960)

3

What is the attenuation

bull

bull = cos

bull n (z) is the spectral

energy density of background

photons lt=EBL

)(emobs )()( zEeEzE

MAGIC Science 2008

4

(An approximation)

bull Neglecting evolutionary effects for simplicity

1

Coppi amp Aharonian ApJ 1997

)(emobs )()(

1

)()(

E

D

eEDE

E

DDE

5

Consequencesbull Since becomes lt RHubble for E gt 100 GeV

ndash The observed flux should be exponentially suppressed at large distances so that very far-away sources should become invisible as energy increases

ndash The observed flux should be exponentially suppressed at VHE so that the SED should be steeper than the emitted one

6

The VHE Universe far awayhellip

35 SourceshellipPKS 0447-439 z=020 HESS 20091ES 1011+496 z=021 MAGIC 20071ES 0414+009 z=029 HESS amp Fermi 2009S5 0716+71 z=031plusmn008 MAGIC 20091ES 0502+675 z=034 VERITAS 20093C 66A z=044 VERITAS 2009 3C 279 z=054 MAGIC 2008

7

The distant quasar 3C 279

bull Flat spectrum radio quasar at z=054bull Very bright and strongly variable

ndash Brightest EGRET AGNndash Gamma-ray flares in 1991 and 1996 Fast time variation (~ 6hr in 1996 flare)

bull MAGIC observationsndash 10 h between Jan-April 2006

ndash clear detection on 23rd Feb at 62σ

First FSRQ in TeV -rays

Major jump in redshift

8

The distant quasar 3C 279 is back

bull New observations after optical outburst in Jan 2007

New flare detected

Most distant object ever detected at VHE - two flares (Feb 2006 and Jan 2007)

Emission harder than expected -gt constrains the EBL universe more transparent to -rays than expected

9

Implications on Extragalactic Background Light

e-e+

EBL

VHE

blazarIACT

10

bull At ~05 TeV flux attenuated by 2 orders of magnitudebull The measurement of spectral features permits to constrain EBL models

ndash Power law Γ = 41 plusmn 07 measured up to 05 TeV Spectrum sensitive to 02 to 2 μm

ndash Assume minimum reasonable index Γem = 15

bull Upper limit close to lower limit from galaxy countbull Explanations go

ndash from standard ones

bull very hard emission mechanisms with intrinsic slope lt 15 (Stecker 2008)

bull Very low EBL

ndash to possible evidence for new physics

bull Oscillation to a particle traveling unimpeded

rarr X rarr

Could it be seen

11

Oscillation to an Axion-Like Particle

ndash Oscillation during the propagation DA Roncadelli amp Mansutti [DARMa] PLB2008 PRD2008

ndash Conversion at the emitter (Hooper et al PRD2008)

ndash Mixed mechanisms (Sanchez-Condersquo et al PRD 2009)

ndash hellip

BEaM

Ptrans

1

12

Phenomenology of the oscillations

bull Photon-ALP oscillations are similar to neutrino oscillations but external B is needed

bull Bounds on the parameters M and m ndash CAST amp astrophysical arguments

M gt 114 1010 GeV for m lt 002 eV

ndash Energetics of SN 1987a

M gt 1011 GeV for m lt 10-10 GeV model dependent

13

(DA FARE) Which EBL First analysis of 3C279 EBL model by Kneiske et al 2004

To be updated including Franceschini et al 2008

14

DARMa Intergalactic magnetic fields

Their morphology is poorly known It is supposed that they have a domain-like structure with

bull strength ~ 05 nG bull coherence length ~ 10 Mpc bull random orientation in each domain

NB - Picture consistent with first AUGER data

strength 03 ndash 09 nG for coherence length 1 ndash 10 Mpc

(DA Persic amp Roncadelli MPLA 2008)

15

Hooper amp Serpico (DA FARE)

16

Sanchez-Condersquo et al (DA FARE)

17

Experimental input from more sources at high z MAGIC S5 0716+714

bull After trigger MAGIC observed 26h April 28 Swift reports flux about 50 larger

than that observed in 2007

Apr 29 ATel 1500 MAGIC reports 68 discovery Apr 23-25 F(gt400 GeV) asymp25 Crab

bull 3rd low-peaked VHE blazar after BL Lac amp W comae

bull Host galaxy detected Z=031+-008 =gt 3rd farthest VHE emitter for which the spectral index has been measured

S5 0716+714Trigger in April

2008

Clear signal 68σNew

discoveryarXiv09072386

18

Deformation of the SED

PKS 0447-439 z=020 HESS 20091ES 1011+496 z=021 MAGIC 20071ES 0414+009 z=029 HESS amp Fermi 2009S5 0716+71 z=031plusmn008 MAGIC 20091ES 0502+675 z=034 VERITAS 20093C 66A z=044 VERITAS 2009 3C 279 z=054 MAGIC 2008

hellipand more new sources are coming into the game (VERITAS HESS MAGIC)

19

Other possible explanationsrelated to new physics

bull Kifune 2001 Violation of the Lorentz invariance

bull We should keep in mind thatndash Extraordinary claims require extraordinary evidence

bull New Scientist SciAm blognews hellip and then

ndash Claims must be followed upbull What else do we expect

bull Fundamental implications of unexpected findings

bull Are we seeing a part of the same big picture

2

222 1 ss E

EO

E

EEpc

20

Conclusions

bull The existence of a very light ALP predicted by many extensions of the SM naturally explains the observed transparency of the VHE gamma-ray sky

bull As a bonus it explains why only the most distant AGN seem to demand an unconventional emission spectrum

bull The DaRMa prediction in particular concerns the spectral change of observed AGN flux at VHE and becomes observable if the TeV band is carefully probed

bull It can be tested with IACTs with Fermi and with EAS

21

rdquoA textbook example of the merging of

particle physics and astronomy into the

modern field of astroparticle

physicsrdquo

22

BACKUP

23

PROPAGATION OVER ONE DOMAIN

We work in the short-wavelength approximation so

the beam with energy E is formally a 3-level non

relativistic quantum system described by the wave

equation

with

24

and mixing matrix

which in the presence of absorption becomes

with

25

Hence the conversion probability reads

in terms of the propagation matrix We find

that a nonvanishing conversion probability over the

WHOLE range requires

with

26

In the present situation we have

and so the mixing matrix reduces to

Following Csaki et al ICAP 05 (2003) 005 we

get the explicit form of the propagation matrix

27

PROPAGATION OVER MANY DOMAINS

When all domains are considered at once one has to

allow for the randomness of the direction of B in the

n-th domain Let be the direction of B in the n-th

domain with respect to a FIXED fiducial direction for

all domains and denote by the evolution

matrix in the n-th domain

Then the overall beam propagation is described by

28

We evaluate by numerically

computing and iterating the result

times by randomly choosing each time

We repeat this procedure 5000 times and next

average all these realizations of the propagation

process over all random angles So the PHYSICAL

propagation matrix of the beam is

29

Assuming that the initial state of the beam is

unpolarized and fully made of photons the initial

beam state is

So we finally get

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al

3

What is the attenuation

bull

bull = cos

bull n (z) is the spectral

energy density of background

photons lt=EBL

)(emobs )()( zEeEzE

MAGIC Science 2008

4

(An approximation)

bull Neglecting evolutionary effects for simplicity

1

Coppi amp Aharonian ApJ 1997

)(emobs )()(

1

)()(

E

D

eEDE

E

DDE

5

Consequencesbull Since becomes lt RHubble for E gt 100 GeV

ndash The observed flux should be exponentially suppressed at large distances so that very far-away sources should become invisible as energy increases

ndash The observed flux should be exponentially suppressed at VHE so that the SED should be steeper than the emitted one

6

The VHE Universe far awayhellip

35 SourceshellipPKS 0447-439 z=020 HESS 20091ES 1011+496 z=021 MAGIC 20071ES 0414+009 z=029 HESS amp Fermi 2009S5 0716+71 z=031plusmn008 MAGIC 20091ES 0502+675 z=034 VERITAS 20093C 66A z=044 VERITAS 2009 3C 279 z=054 MAGIC 2008

7

The distant quasar 3C 279

bull Flat spectrum radio quasar at z=054bull Very bright and strongly variable

ndash Brightest EGRET AGNndash Gamma-ray flares in 1991 and 1996 Fast time variation (~ 6hr in 1996 flare)

bull MAGIC observationsndash 10 h between Jan-April 2006

ndash clear detection on 23rd Feb at 62σ

First FSRQ in TeV -rays

Major jump in redshift

8

The distant quasar 3C 279 is back

bull New observations after optical outburst in Jan 2007

New flare detected

Most distant object ever detected at VHE - two flares (Feb 2006 and Jan 2007)

Emission harder than expected -gt constrains the EBL universe more transparent to -rays than expected

9

Implications on Extragalactic Background Light

e-e+

EBL

VHE

blazarIACT

10

bull At ~05 TeV flux attenuated by 2 orders of magnitudebull The measurement of spectral features permits to constrain EBL models

ndash Power law Γ = 41 plusmn 07 measured up to 05 TeV Spectrum sensitive to 02 to 2 μm

ndash Assume minimum reasonable index Γem = 15

bull Upper limit close to lower limit from galaxy countbull Explanations go

ndash from standard ones

bull very hard emission mechanisms with intrinsic slope lt 15 (Stecker 2008)

bull Very low EBL

ndash to possible evidence for new physics

bull Oscillation to a particle traveling unimpeded

rarr X rarr

Could it be seen

11

Oscillation to an Axion-Like Particle

ndash Oscillation during the propagation DA Roncadelli amp Mansutti [DARMa] PLB2008 PRD2008

ndash Conversion at the emitter (Hooper et al PRD2008)

ndash Mixed mechanisms (Sanchez-Condersquo et al PRD 2009)

ndash hellip

BEaM

Ptrans

1

12

Phenomenology of the oscillations

bull Photon-ALP oscillations are similar to neutrino oscillations but external B is needed

bull Bounds on the parameters M and m ndash CAST amp astrophysical arguments

M gt 114 1010 GeV for m lt 002 eV

ndash Energetics of SN 1987a

M gt 1011 GeV for m lt 10-10 GeV model dependent

13

(DA FARE) Which EBL First analysis of 3C279 EBL model by Kneiske et al 2004

To be updated including Franceschini et al 2008

14

DARMa Intergalactic magnetic fields

Their morphology is poorly known It is supposed that they have a domain-like structure with

bull strength ~ 05 nG bull coherence length ~ 10 Mpc bull random orientation in each domain

NB - Picture consistent with first AUGER data

strength 03 ndash 09 nG for coherence length 1 ndash 10 Mpc

(DA Persic amp Roncadelli MPLA 2008)

15

Hooper amp Serpico (DA FARE)

16

Sanchez-Condersquo et al (DA FARE)

17

Experimental input from more sources at high z MAGIC S5 0716+714

bull After trigger MAGIC observed 26h April 28 Swift reports flux about 50 larger

than that observed in 2007

Apr 29 ATel 1500 MAGIC reports 68 discovery Apr 23-25 F(gt400 GeV) asymp25 Crab

bull 3rd low-peaked VHE blazar after BL Lac amp W comae

bull Host galaxy detected Z=031+-008 =gt 3rd farthest VHE emitter for which the spectral index has been measured

S5 0716+714Trigger in April

2008

Clear signal 68σNew

discoveryarXiv09072386

18

Deformation of the SED

PKS 0447-439 z=020 HESS 20091ES 1011+496 z=021 MAGIC 20071ES 0414+009 z=029 HESS amp Fermi 2009S5 0716+71 z=031plusmn008 MAGIC 20091ES 0502+675 z=034 VERITAS 20093C 66A z=044 VERITAS 2009 3C 279 z=054 MAGIC 2008

hellipand more new sources are coming into the game (VERITAS HESS MAGIC)

19

Other possible explanationsrelated to new physics

bull Kifune 2001 Violation of the Lorentz invariance

bull We should keep in mind thatndash Extraordinary claims require extraordinary evidence

bull New Scientist SciAm blognews hellip and then

ndash Claims must be followed upbull What else do we expect

bull Fundamental implications of unexpected findings

bull Are we seeing a part of the same big picture

2

222 1 ss E

EO

E

EEpc

20

Conclusions

bull The existence of a very light ALP predicted by many extensions of the SM naturally explains the observed transparency of the VHE gamma-ray sky

bull As a bonus it explains why only the most distant AGN seem to demand an unconventional emission spectrum

bull The DaRMa prediction in particular concerns the spectral change of observed AGN flux at VHE and becomes observable if the TeV band is carefully probed

bull It can be tested with IACTs with Fermi and with EAS

21

rdquoA textbook example of the merging of

particle physics and astronomy into the

modern field of astroparticle

physicsrdquo

22

BACKUP

23

PROPAGATION OVER ONE DOMAIN

We work in the short-wavelength approximation so

the beam with energy E is formally a 3-level non

relativistic quantum system described by the wave

equation

with

24

and mixing matrix

which in the presence of absorption becomes

with

25

Hence the conversion probability reads

in terms of the propagation matrix We find

that a nonvanishing conversion probability over the

WHOLE range requires

with

26

In the present situation we have

and so the mixing matrix reduces to

Following Csaki et al ICAP 05 (2003) 005 we

get the explicit form of the propagation matrix

27

PROPAGATION OVER MANY DOMAINS

When all domains are considered at once one has to

allow for the randomness of the direction of B in the

n-th domain Let be the direction of B in the n-th

domain with respect to a FIXED fiducial direction for

all domains and denote by the evolution

matrix in the n-th domain

Then the overall beam propagation is described by

28

We evaluate by numerically

computing and iterating the result

times by randomly choosing each time

We repeat this procedure 5000 times and next

average all these realizations of the propagation

process over all random angles So the PHYSICAL

propagation matrix of the beam is

29

Assuming that the initial state of the beam is

unpolarized and fully made of photons the initial

beam state is

So we finally get

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al

4

(An approximation)

bull Neglecting evolutionary effects for simplicity

1

Coppi amp Aharonian ApJ 1997

)(emobs )()(

1

)()(

E

D

eEDE

E

DDE

5

Consequencesbull Since becomes lt RHubble for E gt 100 GeV

ndash The observed flux should be exponentially suppressed at large distances so that very far-away sources should become invisible as energy increases

ndash The observed flux should be exponentially suppressed at VHE so that the SED should be steeper than the emitted one

6

The VHE Universe far awayhellip

35 SourceshellipPKS 0447-439 z=020 HESS 20091ES 1011+496 z=021 MAGIC 20071ES 0414+009 z=029 HESS amp Fermi 2009S5 0716+71 z=031plusmn008 MAGIC 20091ES 0502+675 z=034 VERITAS 20093C 66A z=044 VERITAS 2009 3C 279 z=054 MAGIC 2008

7

The distant quasar 3C 279

bull Flat spectrum radio quasar at z=054bull Very bright and strongly variable

ndash Brightest EGRET AGNndash Gamma-ray flares in 1991 and 1996 Fast time variation (~ 6hr in 1996 flare)

bull MAGIC observationsndash 10 h between Jan-April 2006

ndash clear detection on 23rd Feb at 62σ

First FSRQ in TeV -rays

Major jump in redshift

8

The distant quasar 3C 279 is back

bull New observations after optical outburst in Jan 2007

New flare detected

Most distant object ever detected at VHE - two flares (Feb 2006 and Jan 2007)

Emission harder than expected -gt constrains the EBL universe more transparent to -rays than expected

9

Implications on Extragalactic Background Light

e-e+

EBL

VHE

blazarIACT

10

bull At ~05 TeV flux attenuated by 2 orders of magnitudebull The measurement of spectral features permits to constrain EBL models

ndash Power law Γ = 41 plusmn 07 measured up to 05 TeV Spectrum sensitive to 02 to 2 μm

ndash Assume minimum reasonable index Γem = 15

bull Upper limit close to lower limit from galaxy countbull Explanations go

ndash from standard ones

bull very hard emission mechanisms with intrinsic slope lt 15 (Stecker 2008)

bull Very low EBL

ndash to possible evidence for new physics

bull Oscillation to a particle traveling unimpeded

rarr X rarr

Could it be seen

11

Oscillation to an Axion-Like Particle

ndash Oscillation during the propagation DA Roncadelli amp Mansutti [DARMa] PLB2008 PRD2008

ndash Conversion at the emitter (Hooper et al PRD2008)

ndash Mixed mechanisms (Sanchez-Condersquo et al PRD 2009)

ndash hellip

BEaM

Ptrans

1

12

Phenomenology of the oscillations

bull Photon-ALP oscillations are similar to neutrino oscillations but external B is needed

bull Bounds on the parameters M and m ndash CAST amp astrophysical arguments

M gt 114 1010 GeV for m lt 002 eV

ndash Energetics of SN 1987a

M gt 1011 GeV for m lt 10-10 GeV model dependent

13

(DA FARE) Which EBL First analysis of 3C279 EBL model by Kneiske et al 2004

To be updated including Franceschini et al 2008

14

DARMa Intergalactic magnetic fields

Their morphology is poorly known It is supposed that they have a domain-like structure with

bull strength ~ 05 nG bull coherence length ~ 10 Mpc bull random orientation in each domain

NB - Picture consistent with first AUGER data

strength 03 ndash 09 nG for coherence length 1 ndash 10 Mpc

(DA Persic amp Roncadelli MPLA 2008)

15

Hooper amp Serpico (DA FARE)

16

Sanchez-Condersquo et al (DA FARE)

17

Experimental input from more sources at high z MAGIC S5 0716+714

bull After trigger MAGIC observed 26h April 28 Swift reports flux about 50 larger

than that observed in 2007

Apr 29 ATel 1500 MAGIC reports 68 discovery Apr 23-25 F(gt400 GeV) asymp25 Crab

bull 3rd low-peaked VHE blazar after BL Lac amp W comae

bull Host galaxy detected Z=031+-008 =gt 3rd farthest VHE emitter for which the spectral index has been measured

S5 0716+714Trigger in April

2008

Clear signal 68σNew

discoveryarXiv09072386

18

Deformation of the SED

PKS 0447-439 z=020 HESS 20091ES 1011+496 z=021 MAGIC 20071ES 0414+009 z=029 HESS amp Fermi 2009S5 0716+71 z=031plusmn008 MAGIC 20091ES 0502+675 z=034 VERITAS 20093C 66A z=044 VERITAS 2009 3C 279 z=054 MAGIC 2008

hellipand more new sources are coming into the game (VERITAS HESS MAGIC)

19

Other possible explanationsrelated to new physics

bull Kifune 2001 Violation of the Lorentz invariance

bull We should keep in mind thatndash Extraordinary claims require extraordinary evidence

bull New Scientist SciAm blognews hellip and then

ndash Claims must be followed upbull What else do we expect

bull Fundamental implications of unexpected findings

bull Are we seeing a part of the same big picture

2

222 1 ss E

EO

E

EEpc

20

Conclusions

bull The existence of a very light ALP predicted by many extensions of the SM naturally explains the observed transparency of the VHE gamma-ray sky

bull As a bonus it explains why only the most distant AGN seem to demand an unconventional emission spectrum

bull The DaRMa prediction in particular concerns the spectral change of observed AGN flux at VHE and becomes observable if the TeV band is carefully probed

bull It can be tested with IACTs with Fermi and with EAS

21

rdquoA textbook example of the merging of

particle physics and astronomy into the

modern field of astroparticle

physicsrdquo

22

BACKUP

23

PROPAGATION OVER ONE DOMAIN

We work in the short-wavelength approximation so

the beam with energy E is formally a 3-level non

relativistic quantum system described by the wave

equation

with

24

and mixing matrix

which in the presence of absorption becomes

with

25

Hence the conversion probability reads

in terms of the propagation matrix We find

that a nonvanishing conversion probability over the

WHOLE range requires

with

26

In the present situation we have

and so the mixing matrix reduces to

Following Csaki et al ICAP 05 (2003) 005 we

get the explicit form of the propagation matrix

27

PROPAGATION OVER MANY DOMAINS

When all domains are considered at once one has to

allow for the randomness of the direction of B in the

n-th domain Let be the direction of B in the n-th

domain with respect to a FIXED fiducial direction for

all domains and denote by the evolution

matrix in the n-th domain

Then the overall beam propagation is described by

28

We evaluate by numerically

computing and iterating the result

times by randomly choosing each time

We repeat this procedure 5000 times and next

average all these realizations of the propagation

process over all random angles So the PHYSICAL

propagation matrix of the beam is

29

Assuming that the initial state of the beam is

unpolarized and fully made of photons the initial

beam state is

So we finally get

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al

5

Consequencesbull Since becomes lt RHubble for E gt 100 GeV

ndash The observed flux should be exponentially suppressed at large distances so that very far-away sources should become invisible as energy increases

ndash The observed flux should be exponentially suppressed at VHE so that the SED should be steeper than the emitted one

6

The VHE Universe far awayhellip

35 SourceshellipPKS 0447-439 z=020 HESS 20091ES 1011+496 z=021 MAGIC 20071ES 0414+009 z=029 HESS amp Fermi 2009S5 0716+71 z=031plusmn008 MAGIC 20091ES 0502+675 z=034 VERITAS 20093C 66A z=044 VERITAS 2009 3C 279 z=054 MAGIC 2008

7

The distant quasar 3C 279

bull Flat spectrum radio quasar at z=054bull Very bright and strongly variable

ndash Brightest EGRET AGNndash Gamma-ray flares in 1991 and 1996 Fast time variation (~ 6hr in 1996 flare)

bull MAGIC observationsndash 10 h between Jan-April 2006

ndash clear detection on 23rd Feb at 62σ

First FSRQ in TeV -rays

Major jump in redshift

8

The distant quasar 3C 279 is back

bull New observations after optical outburst in Jan 2007

New flare detected

Most distant object ever detected at VHE - two flares (Feb 2006 and Jan 2007)

Emission harder than expected -gt constrains the EBL universe more transparent to -rays than expected

9

Implications on Extragalactic Background Light

e-e+

EBL

VHE

blazarIACT

10

bull At ~05 TeV flux attenuated by 2 orders of magnitudebull The measurement of spectral features permits to constrain EBL models

ndash Power law Γ = 41 plusmn 07 measured up to 05 TeV Spectrum sensitive to 02 to 2 μm

ndash Assume minimum reasonable index Γem = 15

bull Upper limit close to lower limit from galaxy countbull Explanations go

ndash from standard ones

bull very hard emission mechanisms with intrinsic slope lt 15 (Stecker 2008)

bull Very low EBL

ndash to possible evidence for new physics

bull Oscillation to a particle traveling unimpeded

rarr X rarr

Could it be seen

11

Oscillation to an Axion-Like Particle

ndash Oscillation during the propagation DA Roncadelli amp Mansutti [DARMa] PLB2008 PRD2008

ndash Conversion at the emitter (Hooper et al PRD2008)

ndash Mixed mechanisms (Sanchez-Condersquo et al PRD 2009)

ndash hellip

BEaM

Ptrans

1

12

Phenomenology of the oscillations

bull Photon-ALP oscillations are similar to neutrino oscillations but external B is needed

bull Bounds on the parameters M and m ndash CAST amp astrophysical arguments

M gt 114 1010 GeV for m lt 002 eV

ndash Energetics of SN 1987a

M gt 1011 GeV for m lt 10-10 GeV model dependent

13

(DA FARE) Which EBL First analysis of 3C279 EBL model by Kneiske et al 2004

To be updated including Franceschini et al 2008

14

DARMa Intergalactic magnetic fields

Their morphology is poorly known It is supposed that they have a domain-like structure with

bull strength ~ 05 nG bull coherence length ~ 10 Mpc bull random orientation in each domain

NB - Picture consistent with first AUGER data

strength 03 ndash 09 nG for coherence length 1 ndash 10 Mpc

(DA Persic amp Roncadelli MPLA 2008)

15

Hooper amp Serpico (DA FARE)

16

Sanchez-Condersquo et al (DA FARE)

17

Experimental input from more sources at high z MAGIC S5 0716+714

bull After trigger MAGIC observed 26h April 28 Swift reports flux about 50 larger

than that observed in 2007

Apr 29 ATel 1500 MAGIC reports 68 discovery Apr 23-25 F(gt400 GeV) asymp25 Crab

bull 3rd low-peaked VHE blazar after BL Lac amp W comae

bull Host galaxy detected Z=031+-008 =gt 3rd farthest VHE emitter for which the spectral index has been measured

S5 0716+714Trigger in April

2008

Clear signal 68σNew

discoveryarXiv09072386

18

Deformation of the SED

PKS 0447-439 z=020 HESS 20091ES 1011+496 z=021 MAGIC 20071ES 0414+009 z=029 HESS amp Fermi 2009S5 0716+71 z=031plusmn008 MAGIC 20091ES 0502+675 z=034 VERITAS 20093C 66A z=044 VERITAS 2009 3C 279 z=054 MAGIC 2008

hellipand more new sources are coming into the game (VERITAS HESS MAGIC)

19

Other possible explanationsrelated to new physics

bull Kifune 2001 Violation of the Lorentz invariance

bull We should keep in mind thatndash Extraordinary claims require extraordinary evidence

bull New Scientist SciAm blognews hellip and then

ndash Claims must be followed upbull What else do we expect

bull Fundamental implications of unexpected findings

bull Are we seeing a part of the same big picture

2

222 1 ss E

EO

E

EEpc

20

Conclusions

bull The existence of a very light ALP predicted by many extensions of the SM naturally explains the observed transparency of the VHE gamma-ray sky

bull As a bonus it explains why only the most distant AGN seem to demand an unconventional emission spectrum

bull The DaRMa prediction in particular concerns the spectral change of observed AGN flux at VHE and becomes observable if the TeV band is carefully probed

bull It can be tested with IACTs with Fermi and with EAS

21

rdquoA textbook example of the merging of

particle physics and astronomy into the

modern field of astroparticle

physicsrdquo

22

BACKUP

23

PROPAGATION OVER ONE DOMAIN

We work in the short-wavelength approximation so

the beam with energy E is formally a 3-level non

relativistic quantum system described by the wave

equation

with

24

and mixing matrix

which in the presence of absorption becomes

with

25

Hence the conversion probability reads

in terms of the propagation matrix We find

that a nonvanishing conversion probability over the

WHOLE range requires

with

26

In the present situation we have

and so the mixing matrix reduces to

Following Csaki et al ICAP 05 (2003) 005 we

get the explicit form of the propagation matrix

27

PROPAGATION OVER MANY DOMAINS

When all domains are considered at once one has to

allow for the randomness of the direction of B in the

n-th domain Let be the direction of B in the n-th

domain with respect to a FIXED fiducial direction for

all domains and denote by the evolution

matrix in the n-th domain

Then the overall beam propagation is described by

28

We evaluate by numerically

computing and iterating the result

times by randomly choosing each time

We repeat this procedure 5000 times and next

average all these realizations of the propagation

process over all random angles So the PHYSICAL

propagation matrix of the beam is

29

Assuming that the initial state of the beam is

unpolarized and fully made of photons the initial

beam state is

So we finally get

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al

6

The VHE Universe far awayhellip

35 SourceshellipPKS 0447-439 z=020 HESS 20091ES 1011+496 z=021 MAGIC 20071ES 0414+009 z=029 HESS amp Fermi 2009S5 0716+71 z=031plusmn008 MAGIC 20091ES 0502+675 z=034 VERITAS 20093C 66A z=044 VERITAS 2009 3C 279 z=054 MAGIC 2008

7

The distant quasar 3C 279

bull Flat spectrum radio quasar at z=054bull Very bright and strongly variable

ndash Brightest EGRET AGNndash Gamma-ray flares in 1991 and 1996 Fast time variation (~ 6hr in 1996 flare)

bull MAGIC observationsndash 10 h between Jan-April 2006

ndash clear detection on 23rd Feb at 62σ

First FSRQ in TeV -rays

Major jump in redshift

8

The distant quasar 3C 279 is back

bull New observations after optical outburst in Jan 2007

New flare detected

Most distant object ever detected at VHE - two flares (Feb 2006 and Jan 2007)

Emission harder than expected -gt constrains the EBL universe more transparent to -rays than expected

9

Implications on Extragalactic Background Light

e-e+

EBL

VHE

blazarIACT

10

bull At ~05 TeV flux attenuated by 2 orders of magnitudebull The measurement of spectral features permits to constrain EBL models

ndash Power law Γ = 41 plusmn 07 measured up to 05 TeV Spectrum sensitive to 02 to 2 μm

ndash Assume minimum reasonable index Γem = 15

bull Upper limit close to lower limit from galaxy countbull Explanations go

ndash from standard ones

bull very hard emission mechanisms with intrinsic slope lt 15 (Stecker 2008)

bull Very low EBL

ndash to possible evidence for new physics

bull Oscillation to a particle traveling unimpeded

rarr X rarr

Could it be seen

11

Oscillation to an Axion-Like Particle

ndash Oscillation during the propagation DA Roncadelli amp Mansutti [DARMa] PLB2008 PRD2008

ndash Conversion at the emitter (Hooper et al PRD2008)

ndash Mixed mechanisms (Sanchez-Condersquo et al PRD 2009)

ndash hellip

BEaM

Ptrans

1

12

Phenomenology of the oscillations

bull Photon-ALP oscillations are similar to neutrino oscillations but external B is needed

bull Bounds on the parameters M and m ndash CAST amp astrophysical arguments

M gt 114 1010 GeV for m lt 002 eV

ndash Energetics of SN 1987a

M gt 1011 GeV for m lt 10-10 GeV model dependent

13

(DA FARE) Which EBL First analysis of 3C279 EBL model by Kneiske et al 2004

To be updated including Franceschini et al 2008

14

DARMa Intergalactic magnetic fields

Their morphology is poorly known It is supposed that they have a domain-like structure with

bull strength ~ 05 nG bull coherence length ~ 10 Mpc bull random orientation in each domain

NB - Picture consistent with first AUGER data

strength 03 ndash 09 nG for coherence length 1 ndash 10 Mpc

(DA Persic amp Roncadelli MPLA 2008)

15

Hooper amp Serpico (DA FARE)

16

Sanchez-Condersquo et al (DA FARE)

17

Experimental input from more sources at high z MAGIC S5 0716+714

bull After trigger MAGIC observed 26h April 28 Swift reports flux about 50 larger

than that observed in 2007

Apr 29 ATel 1500 MAGIC reports 68 discovery Apr 23-25 F(gt400 GeV) asymp25 Crab

bull 3rd low-peaked VHE blazar after BL Lac amp W comae

bull Host galaxy detected Z=031+-008 =gt 3rd farthest VHE emitter for which the spectral index has been measured

S5 0716+714Trigger in April

2008

Clear signal 68σNew

discoveryarXiv09072386

18

Deformation of the SED

PKS 0447-439 z=020 HESS 20091ES 1011+496 z=021 MAGIC 20071ES 0414+009 z=029 HESS amp Fermi 2009S5 0716+71 z=031plusmn008 MAGIC 20091ES 0502+675 z=034 VERITAS 20093C 66A z=044 VERITAS 2009 3C 279 z=054 MAGIC 2008

hellipand more new sources are coming into the game (VERITAS HESS MAGIC)

19

Other possible explanationsrelated to new physics

bull Kifune 2001 Violation of the Lorentz invariance

bull We should keep in mind thatndash Extraordinary claims require extraordinary evidence

bull New Scientist SciAm blognews hellip and then

ndash Claims must be followed upbull What else do we expect

bull Fundamental implications of unexpected findings

bull Are we seeing a part of the same big picture

2

222 1 ss E

EO

E

EEpc

20

Conclusions

bull The existence of a very light ALP predicted by many extensions of the SM naturally explains the observed transparency of the VHE gamma-ray sky

bull As a bonus it explains why only the most distant AGN seem to demand an unconventional emission spectrum

bull The DaRMa prediction in particular concerns the spectral change of observed AGN flux at VHE and becomes observable if the TeV band is carefully probed

bull It can be tested with IACTs with Fermi and with EAS

21

rdquoA textbook example of the merging of

particle physics and astronomy into the

modern field of astroparticle

physicsrdquo

22

BACKUP

23

PROPAGATION OVER ONE DOMAIN

We work in the short-wavelength approximation so

the beam with energy E is formally a 3-level non

relativistic quantum system described by the wave

equation

with

24

and mixing matrix

which in the presence of absorption becomes

with

25

Hence the conversion probability reads

in terms of the propagation matrix We find

that a nonvanishing conversion probability over the

WHOLE range requires

with

26

In the present situation we have

and so the mixing matrix reduces to

Following Csaki et al ICAP 05 (2003) 005 we

get the explicit form of the propagation matrix

27

PROPAGATION OVER MANY DOMAINS

When all domains are considered at once one has to

allow for the randomness of the direction of B in the

n-th domain Let be the direction of B in the n-th

domain with respect to a FIXED fiducial direction for

all domains and denote by the evolution

matrix in the n-th domain

Then the overall beam propagation is described by

28

We evaluate by numerically

computing and iterating the result

times by randomly choosing each time

We repeat this procedure 5000 times and next

average all these realizations of the propagation

process over all random angles So the PHYSICAL

propagation matrix of the beam is

29

Assuming that the initial state of the beam is

unpolarized and fully made of photons the initial

beam state is

So we finally get

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al

7

The distant quasar 3C 279

bull Flat spectrum radio quasar at z=054bull Very bright and strongly variable

ndash Brightest EGRET AGNndash Gamma-ray flares in 1991 and 1996 Fast time variation (~ 6hr in 1996 flare)

bull MAGIC observationsndash 10 h between Jan-April 2006

ndash clear detection on 23rd Feb at 62σ

First FSRQ in TeV -rays

Major jump in redshift

8

The distant quasar 3C 279 is back

bull New observations after optical outburst in Jan 2007

New flare detected

Most distant object ever detected at VHE - two flares (Feb 2006 and Jan 2007)

Emission harder than expected -gt constrains the EBL universe more transparent to -rays than expected

9

Implications on Extragalactic Background Light

e-e+

EBL

VHE

blazarIACT

10

bull At ~05 TeV flux attenuated by 2 orders of magnitudebull The measurement of spectral features permits to constrain EBL models

ndash Power law Γ = 41 plusmn 07 measured up to 05 TeV Spectrum sensitive to 02 to 2 μm

ndash Assume minimum reasonable index Γem = 15

bull Upper limit close to lower limit from galaxy countbull Explanations go

ndash from standard ones

bull very hard emission mechanisms with intrinsic slope lt 15 (Stecker 2008)

bull Very low EBL

ndash to possible evidence for new physics

bull Oscillation to a particle traveling unimpeded

rarr X rarr

Could it be seen

11

Oscillation to an Axion-Like Particle

ndash Oscillation during the propagation DA Roncadelli amp Mansutti [DARMa] PLB2008 PRD2008

ndash Conversion at the emitter (Hooper et al PRD2008)

ndash Mixed mechanisms (Sanchez-Condersquo et al PRD 2009)

ndash hellip

BEaM

Ptrans

1

12

Phenomenology of the oscillations

bull Photon-ALP oscillations are similar to neutrino oscillations but external B is needed

bull Bounds on the parameters M and m ndash CAST amp astrophysical arguments

M gt 114 1010 GeV for m lt 002 eV

ndash Energetics of SN 1987a

M gt 1011 GeV for m lt 10-10 GeV model dependent

13

(DA FARE) Which EBL First analysis of 3C279 EBL model by Kneiske et al 2004

To be updated including Franceschini et al 2008

14

DARMa Intergalactic magnetic fields

Their morphology is poorly known It is supposed that they have a domain-like structure with

bull strength ~ 05 nG bull coherence length ~ 10 Mpc bull random orientation in each domain

NB - Picture consistent with first AUGER data

strength 03 ndash 09 nG for coherence length 1 ndash 10 Mpc

(DA Persic amp Roncadelli MPLA 2008)

15

Hooper amp Serpico (DA FARE)

16

Sanchez-Condersquo et al (DA FARE)

17

Experimental input from more sources at high z MAGIC S5 0716+714

bull After trigger MAGIC observed 26h April 28 Swift reports flux about 50 larger

than that observed in 2007

Apr 29 ATel 1500 MAGIC reports 68 discovery Apr 23-25 F(gt400 GeV) asymp25 Crab

bull 3rd low-peaked VHE blazar after BL Lac amp W comae

bull Host galaxy detected Z=031+-008 =gt 3rd farthest VHE emitter for which the spectral index has been measured

S5 0716+714Trigger in April

2008

Clear signal 68σNew

discoveryarXiv09072386

18

Deformation of the SED

PKS 0447-439 z=020 HESS 20091ES 1011+496 z=021 MAGIC 20071ES 0414+009 z=029 HESS amp Fermi 2009S5 0716+71 z=031plusmn008 MAGIC 20091ES 0502+675 z=034 VERITAS 20093C 66A z=044 VERITAS 2009 3C 279 z=054 MAGIC 2008

hellipand more new sources are coming into the game (VERITAS HESS MAGIC)

19

Other possible explanationsrelated to new physics

bull Kifune 2001 Violation of the Lorentz invariance

bull We should keep in mind thatndash Extraordinary claims require extraordinary evidence

bull New Scientist SciAm blognews hellip and then

ndash Claims must be followed upbull What else do we expect

bull Fundamental implications of unexpected findings

bull Are we seeing a part of the same big picture

2

222 1 ss E

EO

E

EEpc

20

Conclusions

bull The existence of a very light ALP predicted by many extensions of the SM naturally explains the observed transparency of the VHE gamma-ray sky

bull As a bonus it explains why only the most distant AGN seem to demand an unconventional emission spectrum

bull The DaRMa prediction in particular concerns the spectral change of observed AGN flux at VHE and becomes observable if the TeV band is carefully probed

bull It can be tested with IACTs with Fermi and with EAS

21

rdquoA textbook example of the merging of

particle physics and astronomy into the

modern field of astroparticle

physicsrdquo

22

BACKUP

23

PROPAGATION OVER ONE DOMAIN

We work in the short-wavelength approximation so

the beam with energy E is formally a 3-level non

relativistic quantum system described by the wave

equation

with

24

and mixing matrix

which in the presence of absorption becomes

with

25

Hence the conversion probability reads

in terms of the propagation matrix We find

that a nonvanishing conversion probability over the

WHOLE range requires

with

26

In the present situation we have

and so the mixing matrix reduces to

Following Csaki et al ICAP 05 (2003) 005 we

get the explicit form of the propagation matrix

27

PROPAGATION OVER MANY DOMAINS

When all domains are considered at once one has to

allow for the randomness of the direction of B in the

n-th domain Let be the direction of B in the n-th

domain with respect to a FIXED fiducial direction for

all domains and denote by the evolution

matrix in the n-th domain

Then the overall beam propagation is described by

28

We evaluate by numerically

computing and iterating the result

times by randomly choosing each time

We repeat this procedure 5000 times and next

average all these realizations of the propagation

process over all random angles So the PHYSICAL

propagation matrix of the beam is

29

Assuming that the initial state of the beam is

unpolarized and fully made of photons the initial

beam state is

So we finally get

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al

8

The distant quasar 3C 279 is back

bull New observations after optical outburst in Jan 2007

New flare detected

Most distant object ever detected at VHE - two flares (Feb 2006 and Jan 2007)

Emission harder than expected -gt constrains the EBL universe more transparent to -rays than expected

9

Implications on Extragalactic Background Light

e-e+

EBL

VHE

blazarIACT

10

bull At ~05 TeV flux attenuated by 2 orders of magnitudebull The measurement of spectral features permits to constrain EBL models

ndash Power law Γ = 41 plusmn 07 measured up to 05 TeV Spectrum sensitive to 02 to 2 μm

ndash Assume minimum reasonable index Γem = 15

bull Upper limit close to lower limit from galaxy countbull Explanations go

ndash from standard ones

bull very hard emission mechanisms with intrinsic slope lt 15 (Stecker 2008)

bull Very low EBL

ndash to possible evidence for new physics

bull Oscillation to a particle traveling unimpeded

rarr X rarr

Could it be seen

11

Oscillation to an Axion-Like Particle

ndash Oscillation during the propagation DA Roncadelli amp Mansutti [DARMa] PLB2008 PRD2008

ndash Conversion at the emitter (Hooper et al PRD2008)

ndash Mixed mechanisms (Sanchez-Condersquo et al PRD 2009)

ndash hellip

BEaM

Ptrans

1

12

Phenomenology of the oscillations

bull Photon-ALP oscillations are similar to neutrino oscillations but external B is needed

bull Bounds on the parameters M and m ndash CAST amp astrophysical arguments

M gt 114 1010 GeV for m lt 002 eV

ndash Energetics of SN 1987a

M gt 1011 GeV for m lt 10-10 GeV model dependent

13

(DA FARE) Which EBL First analysis of 3C279 EBL model by Kneiske et al 2004

To be updated including Franceschini et al 2008

14

DARMa Intergalactic magnetic fields

Their morphology is poorly known It is supposed that they have a domain-like structure with

bull strength ~ 05 nG bull coherence length ~ 10 Mpc bull random orientation in each domain

NB - Picture consistent with first AUGER data

strength 03 ndash 09 nG for coherence length 1 ndash 10 Mpc

(DA Persic amp Roncadelli MPLA 2008)

15

Hooper amp Serpico (DA FARE)

16

Sanchez-Condersquo et al (DA FARE)

17

Experimental input from more sources at high z MAGIC S5 0716+714

bull After trigger MAGIC observed 26h April 28 Swift reports flux about 50 larger

than that observed in 2007

Apr 29 ATel 1500 MAGIC reports 68 discovery Apr 23-25 F(gt400 GeV) asymp25 Crab

bull 3rd low-peaked VHE blazar after BL Lac amp W comae

bull Host galaxy detected Z=031+-008 =gt 3rd farthest VHE emitter for which the spectral index has been measured

S5 0716+714Trigger in April

2008

Clear signal 68σNew

discoveryarXiv09072386

18

Deformation of the SED

PKS 0447-439 z=020 HESS 20091ES 1011+496 z=021 MAGIC 20071ES 0414+009 z=029 HESS amp Fermi 2009S5 0716+71 z=031plusmn008 MAGIC 20091ES 0502+675 z=034 VERITAS 20093C 66A z=044 VERITAS 2009 3C 279 z=054 MAGIC 2008

hellipand more new sources are coming into the game (VERITAS HESS MAGIC)

19

Other possible explanationsrelated to new physics

bull Kifune 2001 Violation of the Lorentz invariance

bull We should keep in mind thatndash Extraordinary claims require extraordinary evidence

bull New Scientist SciAm blognews hellip and then

ndash Claims must be followed upbull What else do we expect

bull Fundamental implications of unexpected findings

bull Are we seeing a part of the same big picture

2

222 1 ss E

EO

E

EEpc

20

Conclusions

bull The existence of a very light ALP predicted by many extensions of the SM naturally explains the observed transparency of the VHE gamma-ray sky

bull As a bonus it explains why only the most distant AGN seem to demand an unconventional emission spectrum

bull The DaRMa prediction in particular concerns the spectral change of observed AGN flux at VHE and becomes observable if the TeV band is carefully probed

bull It can be tested with IACTs with Fermi and with EAS

21

rdquoA textbook example of the merging of

particle physics and astronomy into the

modern field of astroparticle

physicsrdquo

22

BACKUP

23

PROPAGATION OVER ONE DOMAIN

We work in the short-wavelength approximation so

the beam with energy E is formally a 3-level non

relativistic quantum system described by the wave

equation

with

24

and mixing matrix

which in the presence of absorption becomes

with

25

Hence the conversion probability reads

in terms of the propagation matrix We find

that a nonvanishing conversion probability over the

WHOLE range requires

with

26

In the present situation we have

and so the mixing matrix reduces to

Following Csaki et al ICAP 05 (2003) 005 we

get the explicit form of the propagation matrix

27

PROPAGATION OVER MANY DOMAINS

When all domains are considered at once one has to

allow for the randomness of the direction of B in the

n-th domain Let be the direction of B in the n-th

domain with respect to a FIXED fiducial direction for

all domains and denote by the evolution

matrix in the n-th domain

Then the overall beam propagation is described by

28

We evaluate by numerically

computing and iterating the result

times by randomly choosing each time

We repeat this procedure 5000 times and next

average all these realizations of the propagation

process over all random angles So the PHYSICAL

propagation matrix of the beam is

29

Assuming that the initial state of the beam is

unpolarized and fully made of photons the initial

beam state is

So we finally get

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al

9

Implications on Extragalactic Background Light

e-e+

EBL

VHE

blazarIACT

10

bull At ~05 TeV flux attenuated by 2 orders of magnitudebull The measurement of spectral features permits to constrain EBL models

ndash Power law Γ = 41 plusmn 07 measured up to 05 TeV Spectrum sensitive to 02 to 2 μm

ndash Assume minimum reasonable index Γem = 15

bull Upper limit close to lower limit from galaxy countbull Explanations go

ndash from standard ones

bull very hard emission mechanisms with intrinsic slope lt 15 (Stecker 2008)

bull Very low EBL

ndash to possible evidence for new physics

bull Oscillation to a particle traveling unimpeded

rarr X rarr

Could it be seen

11

Oscillation to an Axion-Like Particle

ndash Oscillation during the propagation DA Roncadelli amp Mansutti [DARMa] PLB2008 PRD2008

ndash Conversion at the emitter (Hooper et al PRD2008)

ndash Mixed mechanisms (Sanchez-Condersquo et al PRD 2009)

ndash hellip

BEaM

Ptrans

1

12

Phenomenology of the oscillations

bull Photon-ALP oscillations are similar to neutrino oscillations but external B is needed

bull Bounds on the parameters M and m ndash CAST amp astrophysical arguments

M gt 114 1010 GeV for m lt 002 eV

ndash Energetics of SN 1987a

M gt 1011 GeV for m lt 10-10 GeV model dependent

13

(DA FARE) Which EBL First analysis of 3C279 EBL model by Kneiske et al 2004

To be updated including Franceschini et al 2008

14

DARMa Intergalactic magnetic fields

Their morphology is poorly known It is supposed that they have a domain-like structure with

bull strength ~ 05 nG bull coherence length ~ 10 Mpc bull random orientation in each domain

NB - Picture consistent with first AUGER data

strength 03 ndash 09 nG for coherence length 1 ndash 10 Mpc

(DA Persic amp Roncadelli MPLA 2008)

15

Hooper amp Serpico (DA FARE)

16

Sanchez-Condersquo et al (DA FARE)

17

Experimental input from more sources at high z MAGIC S5 0716+714

bull After trigger MAGIC observed 26h April 28 Swift reports flux about 50 larger

than that observed in 2007

Apr 29 ATel 1500 MAGIC reports 68 discovery Apr 23-25 F(gt400 GeV) asymp25 Crab

bull 3rd low-peaked VHE blazar after BL Lac amp W comae

bull Host galaxy detected Z=031+-008 =gt 3rd farthest VHE emitter for which the spectral index has been measured

S5 0716+714Trigger in April

2008

Clear signal 68σNew

discoveryarXiv09072386

18

Deformation of the SED

PKS 0447-439 z=020 HESS 20091ES 1011+496 z=021 MAGIC 20071ES 0414+009 z=029 HESS amp Fermi 2009S5 0716+71 z=031plusmn008 MAGIC 20091ES 0502+675 z=034 VERITAS 20093C 66A z=044 VERITAS 2009 3C 279 z=054 MAGIC 2008

hellipand more new sources are coming into the game (VERITAS HESS MAGIC)

19

Other possible explanationsrelated to new physics

bull Kifune 2001 Violation of the Lorentz invariance

bull We should keep in mind thatndash Extraordinary claims require extraordinary evidence

bull New Scientist SciAm blognews hellip and then

ndash Claims must be followed upbull What else do we expect

bull Fundamental implications of unexpected findings

bull Are we seeing a part of the same big picture

2

222 1 ss E

EO

E

EEpc

20

Conclusions

bull The existence of a very light ALP predicted by many extensions of the SM naturally explains the observed transparency of the VHE gamma-ray sky

bull As a bonus it explains why only the most distant AGN seem to demand an unconventional emission spectrum

bull The DaRMa prediction in particular concerns the spectral change of observed AGN flux at VHE and becomes observable if the TeV band is carefully probed

bull It can be tested with IACTs with Fermi and with EAS

21

rdquoA textbook example of the merging of

particle physics and astronomy into the

modern field of astroparticle

physicsrdquo

22

BACKUP

23

PROPAGATION OVER ONE DOMAIN

We work in the short-wavelength approximation so

the beam with energy E is formally a 3-level non

relativistic quantum system described by the wave

equation

with

24

and mixing matrix

which in the presence of absorption becomes

with

25

Hence the conversion probability reads

in terms of the propagation matrix We find

that a nonvanishing conversion probability over the

WHOLE range requires

with

26

In the present situation we have

and so the mixing matrix reduces to

Following Csaki et al ICAP 05 (2003) 005 we

get the explicit form of the propagation matrix

27

PROPAGATION OVER MANY DOMAINS

When all domains are considered at once one has to

allow for the randomness of the direction of B in the

n-th domain Let be the direction of B in the n-th

domain with respect to a FIXED fiducial direction for

all domains and denote by the evolution

matrix in the n-th domain

Then the overall beam propagation is described by

28

We evaluate by numerically

computing and iterating the result

times by randomly choosing each time

We repeat this procedure 5000 times and next

average all these realizations of the propagation

process over all random angles So the PHYSICAL

propagation matrix of the beam is

29

Assuming that the initial state of the beam is

unpolarized and fully made of photons the initial

beam state is

So we finally get

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al

10

bull At ~05 TeV flux attenuated by 2 orders of magnitudebull The measurement of spectral features permits to constrain EBL models

ndash Power law Γ = 41 plusmn 07 measured up to 05 TeV Spectrum sensitive to 02 to 2 μm

ndash Assume minimum reasonable index Γem = 15

bull Upper limit close to lower limit from galaxy countbull Explanations go

ndash from standard ones

bull very hard emission mechanisms with intrinsic slope lt 15 (Stecker 2008)

bull Very low EBL

ndash to possible evidence for new physics

bull Oscillation to a particle traveling unimpeded

rarr X rarr

Could it be seen

11

Oscillation to an Axion-Like Particle

ndash Oscillation during the propagation DA Roncadelli amp Mansutti [DARMa] PLB2008 PRD2008

ndash Conversion at the emitter (Hooper et al PRD2008)

ndash Mixed mechanisms (Sanchez-Condersquo et al PRD 2009)

ndash hellip

BEaM

Ptrans

1

12

Phenomenology of the oscillations

bull Photon-ALP oscillations are similar to neutrino oscillations but external B is needed

bull Bounds on the parameters M and m ndash CAST amp astrophysical arguments

M gt 114 1010 GeV for m lt 002 eV

ndash Energetics of SN 1987a

M gt 1011 GeV for m lt 10-10 GeV model dependent

13

(DA FARE) Which EBL First analysis of 3C279 EBL model by Kneiske et al 2004

To be updated including Franceschini et al 2008

14

DARMa Intergalactic magnetic fields

Their morphology is poorly known It is supposed that they have a domain-like structure with

bull strength ~ 05 nG bull coherence length ~ 10 Mpc bull random orientation in each domain

NB - Picture consistent with first AUGER data

strength 03 ndash 09 nG for coherence length 1 ndash 10 Mpc

(DA Persic amp Roncadelli MPLA 2008)

15

Hooper amp Serpico (DA FARE)

16

Sanchez-Condersquo et al (DA FARE)

17

Experimental input from more sources at high z MAGIC S5 0716+714

bull After trigger MAGIC observed 26h April 28 Swift reports flux about 50 larger

than that observed in 2007

Apr 29 ATel 1500 MAGIC reports 68 discovery Apr 23-25 F(gt400 GeV) asymp25 Crab

bull 3rd low-peaked VHE blazar after BL Lac amp W comae

bull Host galaxy detected Z=031+-008 =gt 3rd farthest VHE emitter for which the spectral index has been measured

S5 0716+714Trigger in April

2008

Clear signal 68σNew

discoveryarXiv09072386

18

Deformation of the SED

PKS 0447-439 z=020 HESS 20091ES 1011+496 z=021 MAGIC 20071ES 0414+009 z=029 HESS amp Fermi 2009S5 0716+71 z=031plusmn008 MAGIC 20091ES 0502+675 z=034 VERITAS 20093C 66A z=044 VERITAS 2009 3C 279 z=054 MAGIC 2008

hellipand more new sources are coming into the game (VERITAS HESS MAGIC)

19

Other possible explanationsrelated to new physics

bull Kifune 2001 Violation of the Lorentz invariance

bull We should keep in mind thatndash Extraordinary claims require extraordinary evidence

bull New Scientist SciAm blognews hellip and then

ndash Claims must be followed upbull What else do we expect

bull Fundamental implications of unexpected findings

bull Are we seeing a part of the same big picture

2

222 1 ss E

EO

E

EEpc

20

Conclusions

bull The existence of a very light ALP predicted by many extensions of the SM naturally explains the observed transparency of the VHE gamma-ray sky

bull As a bonus it explains why only the most distant AGN seem to demand an unconventional emission spectrum

bull The DaRMa prediction in particular concerns the spectral change of observed AGN flux at VHE and becomes observable if the TeV band is carefully probed

bull It can be tested with IACTs with Fermi and with EAS

21

rdquoA textbook example of the merging of

particle physics and astronomy into the

modern field of astroparticle

physicsrdquo

22

BACKUP

23

PROPAGATION OVER ONE DOMAIN

We work in the short-wavelength approximation so

the beam with energy E is formally a 3-level non

relativistic quantum system described by the wave

equation

with

24

and mixing matrix

which in the presence of absorption becomes

with

25

Hence the conversion probability reads

in terms of the propagation matrix We find

that a nonvanishing conversion probability over the

WHOLE range requires

with

26

In the present situation we have

and so the mixing matrix reduces to

Following Csaki et al ICAP 05 (2003) 005 we

get the explicit form of the propagation matrix

27

PROPAGATION OVER MANY DOMAINS

When all domains are considered at once one has to

allow for the randomness of the direction of B in the

n-th domain Let be the direction of B in the n-th

domain with respect to a FIXED fiducial direction for

all domains and denote by the evolution

matrix in the n-th domain

Then the overall beam propagation is described by

28

We evaluate by numerically

computing and iterating the result

times by randomly choosing each time

We repeat this procedure 5000 times and next

average all these realizations of the propagation

process over all random angles So the PHYSICAL

propagation matrix of the beam is

29

Assuming that the initial state of the beam is

unpolarized and fully made of photons the initial

beam state is

So we finally get

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al

11

Oscillation to an Axion-Like Particle

ndash Oscillation during the propagation DA Roncadelli amp Mansutti [DARMa] PLB2008 PRD2008

ndash Conversion at the emitter (Hooper et al PRD2008)

ndash Mixed mechanisms (Sanchez-Condersquo et al PRD 2009)

ndash hellip

BEaM

Ptrans

1

12

Phenomenology of the oscillations

bull Photon-ALP oscillations are similar to neutrino oscillations but external B is needed

bull Bounds on the parameters M and m ndash CAST amp astrophysical arguments

M gt 114 1010 GeV for m lt 002 eV

ndash Energetics of SN 1987a

M gt 1011 GeV for m lt 10-10 GeV model dependent

13

(DA FARE) Which EBL First analysis of 3C279 EBL model by Kneiske et al 2004

To be updated including Franceschini et al 2008

14

DARMa Intergalactic magnetic fields

Their morphology is poorly known It is supposed that they have a domain-like structure with

bull strength ~ 05 nG bull coherence length ~ 10 Mpc bull random orientation in each domain

NB - Picture consistent with first AUGER data

strength 03 ndash 09 nG for coherence length 1 ndash 10 Mpc

(DA Persic amp Roncadelli MPLA 2008)

15

Hooper amp Serpico (DA FARE)

16

Sanchez-Condersquo et al (DA FARE)

17

Experimental input from more sources at high z MAGIC S5 0716+714

bull After trigger MAGIC observed 26h April 28 Swift reports flux about 50 larger

than that observed in 2007

Apr 29 ATel 1500 MAGIC reports 68 discovery Apr 23-25 F(gt400 GeV) asymp25 Crab

bull 3rd low-peaked VHE blazar after BL Lac amp W comae

bull Host galaxy detected Z=031+-008 =gt 3rd farthest VHE emitter for which the spectral index has been measured

S5 0716+714Trigger in April

2008

Clear signal 68σNew

discoveryarXiv09072386

18

Deformation of the SED

PKS 0447-439 z=020 HESS 20091ES 1011+496 z=021 MAGIC 20071ES 0414+009 z=029 HESS amp Fermi 2009S5 0716+71 z=031plusmn008 MAGIC 20091ES 0502+675 z=034 VERITAS 20093C 66A z=044 VERITAS 2009 3C 279 z=054 MAGIC 2008

hellipand more new sources are coming into the game (VERITAS HESS MAGIC)

19

Other possible explanationsrelated to new physics

bull Kifune 2001 Violation of the Lorentz invariance

bull We should keep in mind thatndash Extraordinary claims require extraordinary evidence

bull New Scientist SciAm blognews hellip and then

ndash Claims must be followed upbull What else do we expect

bull Fundamental implications of unexpected findings

bull Are we seeing a part of the same big picture

2

222 1 ss E

EO

E

EEpc

20

Conclusions

bull The existence of a very light ALP predicted by many extensions of the SM naturally explains the observed transparency of the VHE gamma-ray sky

bull As a bonus it explains why only the most distant AGN seem to demand an unconventional emission spectrum

bull The DaRMa prediction in particular concerns the spectral change of observed AGN flux at VHE and becomes observable if the TeV band is carefully probed

bull It can be tested with IACTs with Fermi and with EAS

21

rdquoA textbook example of the merging of

particle physics and astronomy into the

modern field of astroparticle

physicsrdquo

22

BACKUP

23

PROPAGATION OVER ONE DOMAIN

We work in the short-wavelength approximation so

the beam with energy E is formally a 3-level non

relativistic quantum system described by the wave

equation

with

24

and mixing matrix

which in the presence of absorption becomes

with

25

Hence the conversion probability reads

in terms of the propagation matrix We find

that a nonvanishing conversion probability over the

WHOLE range requires

with

26

In the present situation we have

and so the mixing matrix reduces to

Following Csaki et al ICAP 05 (2003) 005 we

get the explicit form of the propagation matrix

27

PROPAGATION OVER MANY DOMAINS

When all domains are considered at once one has to

allow for the randomness of the direction of B in the

n-th domain Let be the direction of B in the n-th

domain with respect to a FIXED fiducial direction for

all domains and denote by the evolution

matrix in the n-th domain

Then the overall beam propagation is described by

28

We evaluate by numerically

computing and iterating the result

times by randomly choosing each time

We repeat this procedure 5000 times and next

average all these realizations of the propagation

process over all random angles So the PHYSICAL

propagation matrix of the beam is

29

Assuming that the initial state of the beam is

unpolarized and fully made of photons the initial

beam state is

So we finally get

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al

12

Phenomenology of the oscillations

bull Photon-ALP oscillations are similar to neutrino oscillations but external B is needed

bull Bounds on the parameters M and m ndash CAST amp astrophysical arguments

M gt 114 1010 GeV for m lt 002 eV

ndash Energetics of SN 1987a

M gt 1011 GeV for m lt 10-10 GeV model dependent

13

(DA FARE) Which EBL First analysis of 3C279 EBL model by Kneiske et al 2004

To be updated including Franceschini et al 2008

14

DARMa Intergalactic magnetic fields

Their morphology is poorly known It is supposed that they have a domain-like structure with

bull strength ~ 05 nG bull coherence length ~ 10 Mpc bull random orientation in each domain

NB - Picture consistent with first AUGER data

strength 03 ndash 09 nG for coherence length 1 ndash 10 Mpc

(DA Persic amp Roncadelli MPLA 2008)

15

Hooper amp Serpico (DA FARE)

16

Sanchez-Condersquo et al (DA FARE)

17

Experimental input from more sources at high z MAGIC S5 0716+714

bull After trigger MAGIC observed 26h April 28 Swift reports flux about 50 larger

than that observed in 2007

Apr 29 ATel 1500 MAGIC reports 68 discovery Apr 23-25 F(gt400 GeV) asymp25 Crab

bull 3rd low-peaked VHE blazar after BL Lac amp W comae

bull Host galaxy detected Z=031+-008 =gt 3rd farthest VHE emitter for which the spectral index has been measured

S5 0716+714Trigger in April

2008

Clear signal 68σNew

discoveryarXiv09072386

18

Deformation of the SED

PKS 0447-439 z=020 HESS 20091ES 1011+496 z=021 MAGIC 20071ES 0414+009 z=029 HESS amp Fermi 2009S5 0716+71 z=031plusmn008 MAGIC 20091ES 0502+675 z=034 VERITAS 20093C 66A z=044 VERITAS 2009 3C 279 z=054 MAGIC 2008

hellipand more new sources are coming into the game (VERITAS HESS MAGIC)

19

Other possible explanationsrelated to new physics

bull Kifune 2001 Violation of the Lorentz invariance

bull We should keep in mind thatndash Extraordinary claims require extraordinary evidence

bull New Scientist SciAm blognews hellip and then

ndash Claims must be followed upbull What else do we expect

bull Fundamental implications of unexpected findings

bull Are we seeing a part of the same big picture

2

222 1 ss E

EO

E

EEpc

20

Conclusions

bull The existence of a very light ALP predicted by many extensions of the SM naturally explains the observed transparency of the VHE gamma-ray sky

bull As a bonus it explains why only the most distant AGN seem to demand an unconventional emission spectrum

bull The DaRMa prediction in particular concerns the spectral change of observed AGN flux at VHE and becomes observable if the TeV band is carefully probed

bull It can be tested with IACTs with Fermi and with EAS

21

rdquoA textbook example of the merging of

particle physics and astronomy into the

modern field of astroparticle

physicsrdquo

22

BACKUP

23

PROPAGATION OVER ONE DOMAIN

We work in the short-wavelength approximation so

the beam with energy E is formally a 3-level non

relativistic quantum system described by the wave

equation

with

24

and mixing matrix

which in the presence of absorption becomes

with

25

Hence the conversion probability reads

in terms of the propagation matrix We find

that a nonvanishing conversion probability over the

WHOLE range requires

with

26

In the present situation we have

and so the mixing matrix reduces to

Following Csaki et al ICAP 05 (2003) 005 we

get the explicit form of the propagation matrix

27

PROPAGATION OVER MANY DOMAINS

When all domains are considered at once one has to

allow for the randomness of the direction of B in the

n-th domain Let be the direction of B in the n-th

domain with respect to a FIXED fiducial direction for

all domains and denote by the evolution

matrix in the n-th domain

Then the overall beam propagation is described by

28

We evaluate by numerically

computing and iterating the result

times by randomly choosing each time

We repeat this procedure 5000 times and next

average all these realizations of the propagation

process over all random angles So the PHYSICAL

propagation matrix of the beam is

29

Assuming that the initial state of the beam is

unpolarized and fully made of photons the initial

beam state is

So we finally get

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al

13

(DA FARE) Which EBL First analysis of 3C279 EBL model by Kneiske et al 2004

To be updated including Franceschini et al 2008

14

DARMa Intergalactic magnetic fields

Their morphology is poorly known It is supposed that they have a domain-like structure with

bull strength ~ 05 nG bull coherence length ~ 10 Mpc bull random orientation in each domain

NB - Picture consistent with first AUGER data

strength 03 ndash 09 nG for coherence length 1 ndash 10 Mpc

(DA Persic amp Roncadelli MPLA 2008)

15

Hooper amp Serpico (DA FARE)

16

Sanchez-Condersquo et al (DA FARE)

17

Experimental input from more sources at high z MAGIC S5 0716+714

bull After trigger MAGIC observed 26h April 28 Swift reports flux about 50 larger

than that observed in 2007

Apr 29 ATel 1500 MAGIC reports 68 discovery Apr 23-25 F(gt400 GeV) asymp25 Crab

bull 3rd low-peaked VHE blazar after BL Lac amp W comae

bull Host galaxy detected Z=031+-008 =gt 3rd farthest VHE emitter for which the spectral index has been measured

S5 0716+714Trigger in April

2008

Clear signal 68σNew

discoveryarXiv09072386

18

Deformation of the SED

PKS 0447-439 z=020 HESS 20091ES 1011+496 z=021 MAGIC 20071ES 0414+009 z=029 HESS amp Fermi 2009S5 0716+71 z=031plusmn008 MAGIC 20091ES 0502+675 z=034 VERITAS 20093C 66A z=044 VERITAS 2009 3C 279 z=054 MAGIC 2008

hellipand more new sources are coming into the game (VERITAS HESS MAGIC)

19

Other possible explanationsrelated to new physics

bull Kifune 2001 Violation of the Lorentz invariance

bull We should keep in mind thatndash Extraordinary claims require extraordinary evidence

bull New Scientist SciAm blognews hellip and then

ndash Claims must be followed upbull What else do we expect

bull Fundamental implications of unexpected findings

bull Are we seeing a part of the same big picture

2

222 1 ss E

EO

E

EEpc

20

Conclusions

bull The existence of a very light ALP predicted by many extensions of the SM naturally explains the observed transparency of the VHE gamma-ray sky

bull As a bonus it explains why only the most distant AGN seem to demand an unconventional emission spectrum

bull The DaRMa prediction in particular concerns the spectral change of observed AGN flux at VHE and becomes observable if the TeV band is carefully probed

bull It can be tested with IACTs with Fermi and with EAS

21

rdquoA textbook example of the merging of

particle physics and astronomy into the

modern field of astroparticle

physicsrdquo

22

BACKUP

23

PROPAGATION OVER ONE DOMAIN

We work in the short-wavelength approximation so

the beam with energy E is formally a 3-level non

relativistic quantum system described by the wave

equation

with

24

and mixing matrix

which in the presence of absorption becomes

with

25

Hence the conversion probability reads

in terms of the propagation matrix We find

that a nonvanishing conversion probability over the

WHOLE range requires

with

26

In the present situation we have

and so the mixing matrix reduces to

Following Csaki et al ICAP 05 (2003) 005 we

get the explicit form of the propagation matrix

27

PROPAGATION OVER MANY DOMAINS

When all domains are considered at once one has to

allow for the randomness of the direction of B in the

n-th domain Let be the direction of B in the n-th

domain with respect to a FIXED fiducial direction for

all domains and denote by the evolution

matrix in the n-th domain

Then the overall beam propagation is described by

28

We evaluate by numerically

computing and iterating the result

times by randomly choosing each time

We repeat this procedure 5000 times and next

average all these realizations of the propagation

process over all random angles So the PHYSICAL

propagation matrix of the beam is

29

Assuming that the initial state of the beam is

unpolarized and fully made of photons the initial

beam state is

So we finally get

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al

14

DARMa Intergalactic magnetic fields

Their morphology is poorly known It is supposed that they have a domain-like structure with

bull strength ~ 05 nG bull coherence length ~ 10 Mpc bull random orientation in each domain

NB - Picture consistent with first AUGER data

strength 03 ndash 09 nG for coherence length 1 ndash 10 Mpc

(DA Persic amp Roncadelli MPLA 2008)

15

Hooper amp Serpico (DA FARE)

16

Sanchez-Condersquo et al (DA FARE)

17

Experimental input from more sources at high z MAGIC S5 0716+714

bull After trigger MAGIC observed 26h April 28 Swift reports flux about 50 larger

than that observed in 2007

Apr 29 ATel 1500 MAGIC reports 68 discovery Apr 23-25 F(gt400 GeV) asymp25 Crab

bull 3rd low-peaked VHE blazar after BL Lac amp W comae

bull Host galaxy detected Z=031+-008 =gt 3rd farthest VHE emitter for which the spectral index has been measured

S5 0716+714Trigger in April

2008

Clear signal 68σNew

discoveryarXiv09072386

18

Deformation of the SED

PKS 0447-439 z=020 HESS 20091ES 1011+496 z=021 MAGIC 20071ES 0414+009 z=029 HESS amp Fermi 2009S5 0716+71 z=031plusmn008 MAGIC 20091ES 0502+675 z=034 VERITAS 20093C 66A z=044 VERITAS 2009 3C 279 z=054 MAGIC 2008

hellipand more new sources are coming into the game (VERITAS HESS MAGIC)

19

Other possible explanationsrelated to new physics

bull Kifune 2001 Violation of the Lorentz invariance

bull We should keep in mind thatndash Extraordinary claims require extraordinary evidence

bull New Scientist SciAm blognews hellip and then

ndash Claims must be followed upbull What else do we expect

bull Fundamental implications of unexpected findings

bull Are we seeing a part of the same big picture

2

222 1 ss E

EO

E

EEpc

20

Conclusions

bull The existence of a very light ALP predicted by many extensions of the SM naturally explains the observed transparency of the VHE gamma-ray sky

bull As a bonus it explains why only the most distant AGN seem to demand an unconventional emission spectrum

bull The DaRMa prediction in particular concerns the spectral change of observed AGN flux at VHE and becomes observable if the TeV band is carefully probed

bull It can be tested with IACTs with Fermi and with EAS

21

rdquoA textbook example of the merging of

particle physics and astronomy into the

modern field of astroparticle

physicsrdquo

22

BACKUP

23

PROPAGATION OVER ONE DOMAIN

We work in the short-wavelength approximation so

the beam with energy E is formally a 3-level non

relativistic quantum system described by the wave

equation

with

24

and mixing matrix

which in the presence of absorption becomes

with

25

Hence the conversion probability reads

in terms of the propagation matrix We find

that a nonvanishing conversion probability over the

WHOLE range requires

with

26

In the present situation we have

and so the mixing matrix reduces to

Following Csaki et al ICAP 05 (2003) 005 we

get the explicit form of the propagation matrix

27

PROPAGATION OVER MANY DOMAINS

When all domains are considered at once one has to

allow for the randomness of the direction of B in the

n-th domain Let be the direction of B in the n-th

domain with respect to a FIXED fiducial direction for

all domains and denote by the evolution

matrix in the n-th domain

Then the overall beam propagation is described by

28

We evaluate by numerically

computing and iterating the result

times by randomly choosing each time

We repeat this procedure 5000 times and next

average all these realizations of the propagation

process over all random angles So the PHYSICAL

propagation matrix of the beam is

29

Assuming that the initial state of the beam is

unpolarized and fully made of photons the initial

beam state is

So we finally get

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al

15

Hooper amp Serpico (DA FARE)

16

Sanchez-Condersquo et al (DA FARE)

17

Experimental input from more sources at high z MAGIC S5 0716+714

bull After trigger MAGIC observed 26h April 28 Swift reports flux about 50 larger

than that observed in 2007

Apr 29 ATel 1500 MAGIC reports 68 discovery Apr 23-25 F(gt400 GeV) asymp25 Crab

bull 3rd low-peaked VHE blazar after BL Lac amp W comae

bull Host galaxy detected Z=031+-008 =gt 3rd farthest VHE emitter for which the spectral index has been measured

S5 0716+714Trigger in April

2008

Clear signal 68σNew

discoveryarXiv09072386

18

Deformation of the SED

PKS 0447-439 z=020 HESS 20091ES 1011+496 z=021 MAGIC 20071ES 0414+009 z=029 HESS amp Fermi 2009S5 0716+71 z=031plusmn008 MAGIC 20091ES 0502+675 z=034 VERITAS 20093C 66A z=044 VERITAS 2009 3C 279 z=054 MAGIC 2008

hellipand more new sources are coming into the game (VERITAS HESS MAGIC)

19

Other possible explanationsrelated to new physics

bull Kifune 2001 Violation of the Lorentz invariance

bull We should keep in mind thatndash Extraordinary claims require extraordinary evidence

bull New Scientist SciAm blognews hellip and then

ndash Claims must be followed upbull What else do we expect

bull Fundamental implications of unexpected findings

bull Are we seeing a part of the same big picture

2

222 1 ss E

EO

E

EEpc

20

Conclusions

bull The existence of a very light ALP predicted by many extensions of the SM naturally explains the observed transparency of the VHE gamma-ray sky

bull As a bonus it explains why only the most distant AGN seem to demand an unconventional emission spectrum

bull The DaRMa prediction in particular concerns the spectral change of observed AGN flux at VHE and becomes observable if the TeV band is carefully probed

bull It can be tested with IACTs with Fermi and with EAS

21

rdquoA textbook example of the merging of

particle physics and astronomy into the

modern field of astroparticle

physicsrdquo

22

BACKUP

23

PROPAGATION OVER ONE DOMAIN

We work in the short-wavelength approximation so

the beam with energy E is formally a 3-level non

relativistic quantum system described by the wave

equation

with

24

and mixing matrix

which in the presence of absorption becomes

with

25

Hence the conversion probability reads

in terms of the propagation matrix We find

that a nonvanishing conversion probability over the

WHOLE range requires

with

26

In the present situation we have

and so the mixing matrix reduces to

Following Csaki et al ICAP 05 (2003) 005 we

get the explicit form of the propagation matrix

27

PROPAGATION OVER MANY DOMAINS

When all domains are considered at once one has to

allow for the randomness of the direction of B in the

n-th domain Let be the direction of B in the n-th

domain with respect to a FIXED fiducial direction for

all domains and denote by the evolution

matrix in the n-th domain

Then the overall beam propagation is described by

28

We evaluate by numerically

computing and iterating the result

times by randomly choosing each time

We repeat this procedure 5000 times and next

average all these realizations of the propagation

process over all random angles So the PHYSICAL

propagation matrix of the beam is

29

Assuming that the initial state of the beam is

unpolarized and fully made of photons the initial

beam state is

So we finally get

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al

16

Sanchez-Condersquo et al (DA FARE)

17

Experimental input from more sources at high z MAGIC S5 0716+714

bull After trigger MAGIC observed 26h April 28 Swift reports flux about 50 larger

than that observed in 2007

Apr 29 ATel 1500 MAGIC reports 68 discovery Apr 23-25 F(gt400 GeV) asymp25 Crab

bull 3rd low-peaked VHE blazar after BL Lac amp W comae

bull Host galaxy detected Z=031+-008 =gt 3rd farthest VHE emitter for which the spectral index has been measured

S5 0716+714Trigger in April

2008

Clear signal 68σNew

discoveryarXiv09072386

18

Deformation of the SED

PKS 0447-439 z=020 HESS 20091ES 1011+496 z=021 MAGIC 20071ES 0414+009 z=029 HESS amp Fermi 2009S5 0716+71 z=031plusmn008 MAGIC 20091ES 0502+675 z=034 VERITAS 20093C 66A z=044 VERITAS 2009 3C 279 z=054 MAGIC 2008

hellipand more new sources are coming into the game (VERITAS HESS MAGIC)

19

Other possible explanationsrelated to new physics

bull Kifune 2001 Violation of the Lorentz invariance

bull We should keep in mind thatndash Extraordinary claims require extraordinary evidence

bull New Scientist SciAm blognews hellip and then

ndash Claims must be followed upbull What else do we expect

bull Fundamental implications of unexpected findings

bull Are we seeing a part of the same big picture

2

222 1 ss E

EO

E

EEpc

20

Conclusions

bull The existence of a very light ALP predicted by many extensions of the SM naturally explains the observed transparency of the VHE gamma-ray sky

bull As a bonus it explains why only the most distant AGN seem to demand an unconventional emission spectrum

bull The DaRMa prediction in particular concerns the spectral change of observed AGN flux at VHE and becomes observable if the TeV band is carefully probed

bull It can be tested with IACTs with Fermi and with EAS

21

rdquoA textbook example of the merging of

particle physics and astronomy into the

modern field of astroparticle

physicsrdquo

22

BACKUP

23

PROPAGATION OVER ONE DOMAIN

We work in the short-wavelength approximation so

the beam with energy E is formally a 3-level non

relativistic quantum system described by the wave

equation

with

24

and mixing matrix

which in the presence of absorption becomes

with

25

Hence the conversion probability reads

in terms of the propagation matrix We find

that a nonvanishing conversion probability over the

WHOLE range requires

with

26

In the present situation we have

and so the mixing matrix reduces to

Following Csaki et al ICAP 05 (2003) 005 we

get the explicit form of the propagation matrix

27

PROPAGATION OVER MANY DOMAINS

When all domains are considered at once one has to

allow for the randomness of the direction of B in the

n-th domain Let be the direction of B in the n-th

domain with respect to a FIXED fiducial direction for

all domains and denote by the evolution

matrix in the n-th domain

Then the overall beam propagation is described by

28

We evaluate by numerically

computing and iterating the result

times by randomly choosing each time

We repeat this procedure 5000 times and next

average all these realizations of the propagation

process over all random angles So the PHYSICAL

propagation matrix of the beam is

29

Assuming that the initial state of the beam is

unpolarized and fully made of photons the initial

beam state is

So we finally get

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al

17

Experimental input from more sources at high z MAGIC S5 0716+714

bull After trigger MAGIC observed 26h April 28 Swift reports flux about 50 larger

than that observed in 2007

Apr 29 ATel 1500 MAGIC reports 68 discovery Apr 23-25 F(gt400 GeV) asymp25 Crab

bull 3rd low-peaked VHE blazar after BL Lac amp W comae

bull Host galaxy detected Z=031+-008 =gt 3rd farthest VHE emitter for which the spectral index has been measured

S5 0716+714Trigger in April

2008

Clear signal 68σNew

discoveryarXiv09072386

18

Deformation of the SED

PKS 0447-439 z=020 HESS 20091ES 1011+496 z=021 MAGIC 20071ES 0414+009 z=029 HESS amp Fermi 2009S5 0716+71 z=031plusmn008 MAGIC 20091ES 0502+675 z=034 VERITAS 20093C 66A z=044 VERITAS 2009 3C 279 z=054 MAGIC 2008

hellipand more new sources are coming into the game (VERITAS HESS MAGIC)

19

Other possible explanationsrelated to new physics

bull Kifune 2001 Violation of the Lorentz invariance

bull We should keep in mind thatndash Extraordinary claims require extraordinary evidence

bull New Scientist SciAm blognews hellip and then

ndash Claims must be followed upbull What else do we expect

bull Fundamental implications of unexpected findings

bull Are we seeing a part of the same big picture

2

222 1 ss E

EO

E

EEpc

20

Conclusions

bull The existence of a very light ALP predicted by many extensions of the SM naturally explains the observed transparency of the VHE gamma-ray sky

bull As a bonus it explains why only the most distant AGN seem to demand an unconventional emission spectrum

bull The DaRMa prediction in particular concerns the spectral change of observed AGN flux at VHE and becomes observable if the TeV band is carefully probed

bull It can be tested with IACTs with Fermi and with EAS

21

rdquoA textbook example of the merging of

particle physics and astronomy into the

modern field of astroparticle

physicsrdquo

22

BACKUP

23

PROPAGATION OVER ONE DOMAIN

We work in the short-wavelength approximation so

the beam with energy E is formally a 3-level non

relativistic quantum system described by the wave

equation

with

24

and mixing matrix

which in the presence of absorption becomes

with

25

Hence the conversion probability reads

in terms of the propagation matrix We find

that a nonvanishing conversion probability over the

WHOLE range requires

with

26

In the present situation we have

and so the mixing matrix reduces to

Following Csaki et al ICAP 05 (2003) 005 we

get the explicit form of the propagation matrix

27

PROPAGATION OVER MANY DOMAINS

When all domains are considered at once one has to

allow for the randomness of the direction of B in the

n-th domain Let be the direction of B in the n-th

domain with respect to a FIXED fiducial direction for

all domains and denote by the evolution

matrix in the n-th domain

Then the overall beam propagation is described by

28

We evaluate by numerically

computing and iterating the result

times by randomly choosing each time

We repeat this procedure 5000 times and next

average all these realizations of the propagation

process over all random angles So the PHYSICAL

propagation matrix of the beam is

29

Assuming that the initial state of the beam is

unpolarized and fully made of photons the initial

beam state is

So we finally get

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al

18

Deformation of the SED

PKS 0447-439 z=020 HESS 20091ES 1011+496 z=021 MAGIC 20071ES 0414+009 z=029 HESS amp Fermi 2009S5 0716+71 z=031plusmn008 MAGIC 20091ES 0502+675 z=034 VERITAS 20093C 66A z=044 VERITAS 2009 3C 279 z=054 MAGIC 2008

hellipand more new sources are coming into the game (VERITAS HESS MAGIC)

19

Other possible explanationsrelated to new physics

bull Kifune 2001 Violation of the Lorentz invariance

bull We should keep in mind thatndash Extraordinary claims require extraordinary evidence

bull New Scientist SciAm blognews hellip and then

ndash Claims must be followed upbull What else do we expect

bull Fundamental implications of unexpected findings

bull Are we seeing a part of the same big picture

2

222 1 ss E

EO

E

EEpc

20

Conclusions

bull The existence of a very light ALP predicted by many extensions of the SM naturally explains the observed transparency of the VHE gamma-ray sky

bull As a bonus it explains why only the most distant AGN seem to demand an unconventional emission spectrum

bull The DaRMa prediction in particular concerns the spectral change of observed AGN flux at VHE and becomes observable if the TeV band is carefully probed

bull It can be tested with IACTs with Fermi and with EAS

21

rdquoA textbook example of the merging of

particle physics and astronomy into the

modern field of astroparticle

physicsrdquo

22

BACKUP

23

PROPAGATION OVER ONE DOMAIN

We work in the short-wavelength approximation so

the beam with energy E is formally a 3-level non

relativistic quantum system described by the wave

equation

with

24

and mixing matrix

which in the presence of absorption becomes

with

25

Hence the conversion probability reads

in terms of the propagation matrix We find

that a nonvanishing conversion probability over the

WHOLE range requires

with

26

In the present situation we have

and so the mixing matrix reduces to

Following Csaki et al ICAP 05 (2003) 005 we

get the explicit form of the propagation matrix

27

PROPAGATION OVER MANY DOMAINS

When all domains are considered at once one has to

allow for the randomness of the direction of B in the

n-th domain Let be the direction of B in the n-th

domain with respect to a FIXED fiducial direction for

all domains and denote by the evolution

matrix in the n-th domain

Then the overall beam propagation is described by

28

We evaluate by numerically

computing and iterating the result

times by randomly choosing each time

We repeat this procedure 5000 times and next

average all these realizations of the propagation

process over all random angles So the PHYSICAL

propagation matrix of the beam is

29

Assuming that the initial state of the beam is

unpolarized and fully made of photons the initial

beam state is

So we finally get

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al

19

Other possible explanationsrelated to new physics

bull Kifune 2001 Violation of the Lorentz invariance

bull We should keep in mind thatndash Extraordinary claims require extraordinary evidence

bull New Scientist SciAm blognews hellip and then

ndash Claims must be followed upbull What else do we expect

bull Fundamental implications of unexpected findings

bull Are we seeing a part of the same big picture

2

222 1 ss E

EO

E

EEpc

20

Conclusions

bull The existence of a very light ALP predicted by many extensions of the SM naturally explains the observed transparency of the VHE gamma-ray sky

bull As a bonus it explains why only the most distant AGN seem to demand an unconventional emission spectrum

bull The DaRMa prediction in particular concerns the spectral change of observed AGN flux at VHE and becomes observable if the TeV band is carefully probed

bull It can be tested with IACTs with Fermi and with EAS

21

rdquoA textbook example of the merging of

particle physics and astronomy into the

modern field of astroparticle

physicsrdquo

22

BACKUP

23

PROPAGATION OVER ONE DOMAIN

We work in the short-wavelength approximation so

the beam with energy E is formally a 3-level non

relativistic quantum system described by the wave

equation

with

24

and mixing matrix

which in the presence of absorption becomes

with

25

Hence the conversion probability reads

in terms of the propagation matrix We find

that a nonvanishing conversion probability over the

WHOLE range requires

with

26

In the present situation we have

and so the mixing matrix reduces to

Following Csaki et al ICAP 05 (2003) 005 we

get the explicit form of the propagation matrix

27

PROPAGATION OVER MANY DOMAINS

When all domains are considered at once one has to

allow for the randomness of the direction of B in the

n-th domain Let be the direction of B in the n-th

domain with respect to a FIXED fiducial direction for

all domains and denote by the evolution

matrix in the n-th domain

Then the overall beam propagation is described by

28

We evaluate by numerically

computing and iterating the result

times by randomly choosing each time

We repeat this procedure 5000 times and next

average all these realizations of the propagation

process over all random angles So the PHYSICAL

propagation matrix of the beam is

29

Assuming that the initial state of the beam is

unpolarized and fully made of photons the initial

beam state is

So we finally get

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al

20

Conclusions

bull The existence of a very light ALP predicted by many extensions of the SM naturally explains the observed transparency of the VHE gamma-ray sky

bull As a bonus it explains why only the most distant AGN seem to demand an unconventional emission spectrum

bull The DaRMa prediction in particular concerns the spectral change of observed AGN flux at VHE and becomes observable if the TeV band is carefully probed

bull It can be tested with IACTs with Fermi and with EAS

21

rdquoA textbook example of the merging of

particle physics and astronomy into the

modern field of astroparticle

physicsrdquo

22

BACKUP

23

PROPAGATION OVER ONE DOMAIN

We work in the short-wavelength approximation so

the beam with energy E is formally a 3-level non

relativistic quantum system described by the wave

equation

with

24

and mixing matrix

which in the presence of absorption becomes

with

25

Hence the conversion probability reads

in terms of the propagation matrix We find

that a nonvanishing conversion probability over the

WHOLE range requires

with

26

In the present situation we have

and so the mixing matrix reduces to

Following Csaki et al ICAP 05 (2003) 005 we

get the explicit form of the propagation matrix

27

PROPAGATION OVER MANY DOMAINS

When all domains are considered at once one has to

allow for the randomness of the direction of B in the

n-th domain Let be the direction of B in the n-th

domain with respect to a FIXED fiducial direction for

all domains and denote by the evolution

matrix in the n-th domain

Then the overall beam propagation is described by

28

We evaluate by numerically

computing and iterating the result

times by randomly choosing each time

We repeat this procedure 5000 times and next

average all these realizations of the propagation

process over all random angles So the PHYSICAL

propagation matrix of the beam is

29

Assuming that the initial state of the beam is

unpolarized and fully made of photons the initial

beam state is

So we finally get

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al

21

rdquoA textbook example of the merging of

particle physics and astronomy into the

modern field of astroparticle

physicsrdquo

22

BACKUP

23

PROPAGATION OVER ONE DOMAIN

We work in the short-wavelength approximation so

the beam with energy E is formally a 3-level non

relativistic quantum system described by the wave

equation

with

24

and mixing matrix

which in the presence of absorption becomes

with

25

Hence the conversion probability reads

in terms of the propagation matrix We find

that a nonvanishing conversion probability over the

WHOLE range requires

with

26

In the present situation we have

and so the mixing matrix reduces to

Following Csaki et al ICAP 05 (2003) 005 we

get the explicit form of the propagation matrix

27

PROPAGATION OVER MANY DOMAINS

When all domains are considered at once one has to

allow for the randomness of the direction of B in the

n-th domain Let be the direction of B in the n-th

domain with respect to a FIXED fiducial direction for

all domains and denote by the evolution

matrix in the n-th domain

Then the overall beam propagation is described by

28

We evaluate by numerically

computing and iterating the result

times by randomly choosing each time

We repeat this procedure 5000 times and next

average all these realizations of the propagation

process over all random angles So the PHYSICAL

propagation matrix of the beam is

29

Assuming that the initial state of the beam is

unpolarized and fully made of photons the initial

beam state is

So we finally get

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al

22

BACKUP

23

PROPAGATION OVER ONE DOMAIN

We work in the short-wavelength approximation so

the beam with energy E is formally a 3-level non

relativistic quantum system described by the wave

equation

with

24

and mixing matrix

which in the presence of absorption becomes

with

25

Hence the conversion probability reads

in terms of the propagation matrix We find

that a nonvanishing conversion probability over the

WHOLE range requires

with

26

In the present situation we have

and so the mixing matrix reduces to

Following Csaki et al ICAP 05 (2003) 005 we

get the explicit form of the propagation matrix

27

PROPAGATION OVER MANY DOMAINS

When all domains are considered at once one has to

allow for the randomness of the direction of B in the

n-th domain Let be the direction of B in the n-th

domain with respect to a FIXED fiducial direction for

all domains and denote by the evolution

matrix in the n-th domain

Then the overall beam propagation is described by

28

We evaluate by numerically

computing and iterating the result

times by randomly choosing each time

We repeat this procedure 5000 times and next

average all these realizations of the propagation

process over all random angles So the PHYSICAL

propagation matrix of the beam is

29

Assuming that the initial state of the beam is

unpolarized and fully made of photons the initial

beam state is

So we finally get

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al

23

PROPAGATION OVER ONE DOMAIN

We work in the short-wavelength approximation so

the beam with energy E is formally a 3-level non

relativistic quantum system described by the wave

equation

with

24

and mixing matrix

which in the presence of absorption becomes

with

25

Hence the conversion probability reads

in terms of the propagation matrix We find

that a nonvanishing conversion probability over the

WHOLE range requires

with

26

In the present situation we have

and so the mixing matrix reduces to

Following Csaki et al ICAP 05 (2003) 005 we

get the explicit form of the propagation matrix

27

PROPAGATION OVER MANY DOMAINS

When all domains are considered at once one has to

allow for the randomness of the direction of B in the

n-th domain Let be the direction of B in the n-th

domain with respect to a FIXED fiducial direction for

all domains and denote by the evolution

matrix in the n-th domain

Then the overall beam propagation is described by

28

We evaluate by numerically

computing and iterating the result

times by randomly choosing each time

We repeat this procedure 5000 times and next

average all these realizations of the propagation

process over all random angles So the PHYSICAL

propagation matrix of the beam is

29

Assuming that the initial state of the beam is

unpolarized and fully made of photons the initial

beam state is

So we finally get

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al

24

and mixing matrix

which in the presence of absorption becomes

with

25

Hence the conversion probability reads

in terms of the propagation matrix We find

that a nonvanishing conversion probability over the

WHOLE range requires

with

26

In the present situation we have

and so the mixing matrix reduces to

Following Csaki et al ICAP 05 (2003) 005 we

get the explicit form of the propagation matrix

27

PROPAGATION OVER MANY DOMAINS

When all domains are considered at once one has to

allow for the randomness of the direction of B in the

n-th domain Let be the direction of B in the n-th

domain with respect to a FIXED fiducial direction for

all domains and denote by the evolution

matrix in the n-th domain

Then the overall beam propagation is described by

28

We evaluate by numerically

computing and iterating the result

times by randomly choosing each time

We repeat this procedure 5000 times and next

average all these realizations of the propagation

process over all random angles So the PHYSICAL

propagation matrix of the beam is

29

Assuming that the initial state of the beam is

unpolarized and fully made of photons the initial

beam state is

So we finally get

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al

25

Hence the conversion probability reads

in terms of the propagation matrix We find

that a nonvanishing conversion probability over the

WHOLE range requires

with

26

In the present situation we have

and so the mixing matrix reduces to

Following Csaki et al ICAP 05 (2003) 005 we

get the explicit form of the propagation matrix

27

PROPAGATION OVER MANY DOMAINS

When all domains are considered at once one has to

allow for the randomness of the direction of B in the

n-th domain Let be the direction of B in the n-th

domain with respect to a FIXED fiducial direction for

all domains and denote by the evolution

matrix in the n-th domain

Then the overall beam propagation is described by

28

We evaluate by numerically

computing and iterating the result

times by randomly choosing each time

We repeat this procedure 5000 times and next

average all these realizations of the propagation

process over all random angles So the PHYSICAL

propagation matrix of the beam is

29

Assuming that the initial state of the beam is

unpolarized and fully made of photons the initial

beam state is

So we finally get

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al

26

In the present situation we have

and so the mixing matrix reduces to

Following Csaki et al ICAP 05 (2003) 005 we

get the explicit form of the propagation matrix

27

PROPAGATION OVER MANY DOMAINS

When all domains are considered at once one has to

allow for the randomness of the direction of B in the

n-th domain Let be the direction of B in the n-th

domain with respect to a FIXED fiducial direction for

all domains and denote by the evolution

matrix in the n-th domain

Then the overall beam propagation is described by

28

We evaluate by numerically

computing and iterating the result

times by randomly choosing each time

We repeat this procedure 5000 times and next

average all these realizations of the propagation

process over all random angles So the PHYSICAL

propagation matrix of the beam is

29

Assuming that the initial state of the beam is

unpolarized and fully made of photons the initial

beam state is

So we finally get

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al

27

PROPAGATION OVER MANY DOMAINS

When all domains are considered at once one has to

allow for the randomness of the direction of B in the

n-th domain Let be the direction of B in the n-th

domain with respect to a FIXED fiducial direction for

all domains and denote by the evolution

matrix in the n-th domain

Then the overall beam propagation is described by

28

We evaluate by numerically

computing and iterating the result

times by randomly choosing each time

We repeat this procedure 5000 times and next

average all these realizations of the propagation

process over all random angles So the PHYSICAL

propagation matrix of the beam is

29

Assuming that the initial state of the beam is

unpolarized and fully made of photons the initial

beam state is

So we finally get

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al

28

We evaluate by numerically

computing and iterating the result

times by randomly choosing each time

We repeat this procedure 5000 times and next

average all these realizations of the propagation

process over all random angles So the PHYSICAL

propagation matrix of the beam is

29

Assuming that the initial state of the beam is

unpolarized and fully made of photons the initial

beam state is

So we finally get

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al

29

Assuming that the initial state of the beam is

unpolarized and fully made of photons the initial

beam state is

So we finally get

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al

30

Ideal case z = 1 ndash EBL of Franceschini et al

• Possible indirect evidence for axion-like particles from far away AGN
• Intergalactic absorption of VHE photons
• What is the attenuation
• (An approximation)
• Consequences
• The VHE Universe far awayhellip
• The distant quasar 3C 279
• The distant quasar 3C 279 is back
• Implications on Extragalactic Background Light
• Slide 10
• Oscillation to an Axion-Like Particle
• Phenomenology of the oscillations
• (DA FARE) Which EBL
• DARMa Intergalactic magnetic fields
• Hooper amp Serpico (DA FARE)
• Sanchez-Condersquo et al (DA FARE)
• Experimental input from more sources at high z MAGIC S5 0716+714
• Deformation of the SED
• Other possible explanations related to new physics
• Conclusions
• Slide 21
• BACKUP
• PROPAGATION OVER ONE DOMAIN
• Slide 24
• Slide 26
• PROPAGATION OVER MANY DOMAINS
• Slide 28
• Slide 29
• Ideal case z = 1 ndash EBL of Franceschini et al