High Energy Radiation and Cosmic Rays

from Clusters of Galaxies

Susumu Inoue(Nat. Astron. Obs. Japan)

GeV100keV

HESS Auger

GLASTSuzaku

F. Aharonian (MPIK), N. Sugiyama (NAO), P. Coppi (Yale)G. Sigl, E. Armengaud (IAP), F. Miniati (ETH)

collaborators:

ZeV

TeV

current evidence for nonthermal emission: Coma1. introduction

radio Giovannini et al. 93 hard X-rayFusco-Femianoet al. 04

Rossetti &Molendi 04

4.8 detection

no detection

gamma-rayno clear evidence yet!GeV Reimer et al. 03

EUV

Bowyeret al. 04

TeV Perkins et al. 06

large scale structure formation (SF) shocks

formation of galaxies, groups, clusters...= hierarchical, dark matter-driven mergers and accretion→ shock formation → gas heating + nonthermal particle acceleration → nonthermal radiation

cosmological hydro simulations by Ryu et al. 03

shock velocitiesthermal emission

clusters are forming this very moment!

QuickTime˛ Ç∆TIFFÅià≥èkǻǵÅj êLí£ÉvÉçÉOÉâÉÄ

ǙDZÇÃÉsÉNÉ`ÉÉÇ å©ÇÈÇΩÇflÇ…ÇÕïKóvÇ≈Ç∑ÅB

shock Mach numbers & particle spectra

major merger

minor merger, accretion

p=2(M2+1)/(M2-1)Not all SF shocks are equal

also Gabici & Blasi 03 Inoue & Nagashima 05

(test particle)

strong (high M) shock-> hard spectra (p~2)

weak (low M) shock-> soft spectra (p>2)

Ryu et al. 03

Vazza’s poster

primary electron inverse Compton

LIC >~ Lsyn ifB < 3G(1+z)2

keV MeVeV GeV

merger

accretion

TeV

Ec(tIC~tshock)

Emax(tIC~tacc)

E

L

E-2

schematicspectrum

accretion(minor merger)

2. high energy emission processes in clusters

traces shock promptly(annular distribution for accretion shock)

e.g. Hwang 97 Ensslin & Biermann 98 Waxman & Loeb 00 Totani & Kitayama 00shock-accelerated e-+CMB→ e-+

tIC<<tshock

electron relativistic bremsstrahlunggenerally not so efficient

proton-proton 0 and secondary pairs

tloss~(nICMppppc)-1~100 Gyr (n/10-3 cm-3)-1

tconf ~R2/6D(E)~200 Gyr (R/Mpc)2 (D/1029cm2s-1) (E/GeV)1/3

pCR+pICM→ ,

traces gas (centrally peaked) +cosmic rays accumulated over cluster history

e.g. Völk, Aharonian & Breidschwerdt 96 Berezinsky, Blasi & Ptuskin 97

t-integrated Mach no. distribution for individual clusters?steep (p>2) spectra?

0→2+-→e+e-+B(~G)→ syn, e+e-+CMB→ IC

>>tH

GeV

0 merger

TeV E

L schematicspectrum

0 accretion (+ radio galaxy, SN-driven wind)

E-2

e+- IC

MeV

origin of radio halos: primary electron vs p-p secondaryprimary electron

p-p secondary

e.g. Brunetti et al. 01,04turbulent stochastic acceleration?need >GeV “seed” particlesmany uncertain parameters

short trad, but no clear sources

long tpp, large-scale injection Dennison 80

but no spectral steepening requires extremely distributed injection0 gamma-rays close to EGRET upper limits

hybrid (p-p secondary injection + turbulent acceleration) Brunetti & Blasi 05

11

10

9

8

720.520.019.519.018.518.017.5

log E [eV]

UHE proton-induced pair emission from cluster accretion shocks

accel. vs CMB losses, lifetime

photopion

lifetimeescape accel.

Bs=0.1 G

photopair

accel.Bs=1 G

e.g. Coma-like clusterM=2x1015 M(T=8.3 keV)WMAP cosmo. parameters

Inoue, Aharonian & Sugiyama 2005 ApJ 628, L9proton Emax

c.f. Kang, Rachen & Biermann 97

Rs~3.2 MpcVs~2200 km/sBs,eq~ 6 G

Emax~1018-1019 eVphotopair important

tacc=(20/3) rgc/Vs2

shock radius, velocity, etc.

Bohm limit shock accel. time

SNR observations ~1e.g. Völk et al. 05

escape timetesc~R2/D(E=Emax)~R/V~2 Gyr shock lifetimetsl~R/V~2 Gyr < tadiab~6 Gyr

proton injection luminosity in accretion shocks

accretion rate & luminosityM(M,z)=fgasfaccVs

3/GLacc(M,z)=fgasfaccGMM/Rs

~2.7x1046 (fgas/0.16) (facc/0.1) (M/ 2x1015 M)5/3 erg/s

proton luminosity & spectrumLp(M,z)=fpLacc(M,z) fp=0.1Fp(E,M,z) ∝ E-2 exp(-E/Emax)

facc=0.1 normalized from simulationKeshet et al. 03

secondary production and emission processesp+CMB→ p+ e+e-

Ep~1018eV E+-~+-Ep~1015eV, L+-~t+-/tinj f(E>1017.7eV) Lp

→ e+e-+B(~G)→ syn. E~keV-MeV e+e-+CMB→ IC E~TeV-PeV

Aharonian 02 code solve proton & pair kinetic eq.

..

-15

-14

-13

-12

-11

-10

14121086420 log E [eV]

e+e- syn

Lp=2x1045

erg/s

Tinj=2x109 yr, R=3 Mpc

n=10-6

cm-3

D=100 Mpc

B=0.1 (G Ep=8 1x 17 )eV

=.3 B (G Ep=2.5 1x 18 )eV

=1 B (G Ep=8 1x 18 )eV

pp (x1)

e+e- IC

emitted flux

> TeV absorption by IRB, CMBComa-like cluster at D=100 Mpc

- large radiative efficiency from protons- hard (~-1.5) spectrum + rollover- sensitive to B

<-> primary IC, pp 0

(~-2)

emitted flux & detectability Coma-like cluster at D=100 Mpcsensitivities for 1 deg2 extended source diameter ~3 deg

TeV : HESS (~0.1° FOV~5°), MAGIC, CANG. III, VERITAShard X: e.g. NeXT, maybe Suzaku/HXD & XIS

implications UHE p-induced emission in cluster accretion shocks

• UHE proton acceleration maximum E• accretion shock direct obs. evidence still tentative• magnetic fields at cluster outskirts emission sensitive to B <-> pp 0

info on B in LSS filaments, cluster B origin• IR background intrinsic spectra to ~PeV, steady <-> TeV blazars

probe of :

cascade emission: pair halo, background

pre-“absorbed” fluxcascade down to GeV-TeV

cluster pair halos- isotropic (much stronger than beamed sources)- hard spectrum

Inoue, Coppi & Aharonian, in prep.

also for p-p 0 from core

probe of IRB, TeV-PeV power

Aharonian, Coppi & Völk 94Coppi & Aharonian 97

3. UHECRs from cluster accretion shocks?

Norman, Achterberg & Melrose ‘95Kang, Ryu & Jones 96Kang, Rachen & Biermann 97

GRB

AGN jet

clusters

energetic requirements

Lcluster~1046 erg/sncluster~10-6 Mpc-3

Pcluster~~1040 erg s-1Mpc-3

UHECR@1020 eVuCR ~10-20 erg cm-3

CR ~0.3(1) Gyr for p (Fe)PCR ~3x1037 erg s-1Mpc-3 massive clusters (~1015 M)

energetically plausiblebut proton Emax insufficient

oblique shocks do not helpOstrowski & Siemieniec-Ozieblo 00

nuclei from cluster accretion shocks as UHECRs

107

108

109

1010

1011

1018

2 3 4 5 6

1019

2 3 4 5 6

1020

2 3 4 5 6

1021

log E [eV]

56Fe

photodisint

photopair

Bs=0.1 G

Bs=1 G

heavy nuclei Emax

for Bs~1 G, EFe, max>~1020 eV

Inoue, Sigl, Armengaud & Miniatiin prep.

UHE nuclei propagation calculations

56Fe

lifetimeescape

log E [eV]lo

g t ac

c, t lo

ss [y

r]

Bs~1 G Johnston-Hollitt & Ekers 05

- structured IGB models based on cosmological simulations- source density ns~10-6 Mpc-3 ∝ baryon density- source power LCR(M)~ 3x1045 erg/s (fCR/0.1)(M/2x1015 M)5/3

- spectral index p=2, Emax(Z) from tacc vs. tloss, tlife- Galactic CR-like source composition (nFe/np~10-3 at fixed E/A)- CMB+FIRB losses, IGB deflections inc. all secondary nuclei

Feretti & Neumann 06

UHECRs: energy losses during propagation

QuickTime˛ Ç∆ǻǵ êLí£ÉvÉçÉOÉâÉÄ

ǙDZÇÃÉsÉNÉ`ÉÉÇ å©ÇÈÇ…ÇÕïKóvÇ≈Ç∑ÅB

p+CMB→ p+ e+e- Ep>~5x1017eVp+CMB→ p+ Ep>~7x1019eV

Lp, 20eV <~100 Mpc

A+CMB→ A+ e+e-

A+FIRB→ A-iN +iNNagano & Watson 00

Fe

p

E

Lloss

LFe, 20eV <~300 Mpc

protons: photopair+photopion

nuclei: photopair+photodisint.

e.g. Stecker &Salamon 99

E>2x1019 eV no data at all (too low statistics)E<2x1019 eV light dominant but greater uncertainties than commonly believed?

current data on composition HiRes stereo Xmax

Watson astro-ph/0408110

intergalactic B fieldse.g. shock generation modelsbased on cosmological simulations

Sigl, Miniati & Ensslin 03,04

normalized to cluster B fields

should be correlated with large scale struc.

Dolag et al 04, 05Brüggen et al 05

different assumptions, numerical methods-> important quantitative differences

quantitatively very uncertain theoretically and observationally

Galactic B: also importante.g. Yoshiguchi et al, Takami et al

Ryu, Kang & Biermann 98

small box size -> periodic boundaryunconstrained -> average over realizationsno Galactic B

UHE nuclei from clusters: results

with IGB

no IGB

spectra composition

anisotropyspectra, anisotropy, composition• consistent with current HiRes but not AGASA? higher Bs?• predictions: - “GZK” cutoff >1020 eV - heavy dominant >1019 eV - large scale aniso. toward few nearby sources

Auger, TA, EUSO

1020 eV1019 eV 1019 eV 1020 eV

fCR~0.03

fCR~0.005

source composition “Galactic CR-like” (solar metallicity)metallicity at cluster outskirtstentatively observed ~0.1 solar

e.g. Finoguenov et al 03

hard spectra at high E p<~1.5

Drury, Meyer & Ellison 99

nonlinear acceleration effects?

Kang & Jones 05

rigidity selection (heavy enhancement)stronger effects for accretion shocks?

UHE nuclei induced pairs and emission

107

108

109

1010

1011

1018

2 3 4 5 6

1019

2 3 4 5 6

1020

2 3 4 5 6

1021

log E [eV]

56Fe

photodisint

photopair

Bs=0.1 G

Bs=1 G

107

108

109

1010

1011

1018

2 3 4 5 6

1019

2 3 4 5 6

1020

2 3 4 5 6

1021

log E [eV]

16O

nuclei photopair+photodisint. loss importantadditional hard X-ray and -ray emission, broader spectra

56Fe16O

lifetimeescape

direct proof of nuclei accelerationconstrain source compositionpotentially

Ee+e-,A ~ (me /Amp ) Z Ep Ee-,ndec ~ (mn-p /Amp ) Z Ep

Inoue, Sigl & Armengaud, in prep.

hard-X/gamma-ray emission from individual clusters: roundup

MeV, GeV and TeV should look different

outskirts

core

GeV0 merger

TeVE

L

0 accretion(+ radio galaxySN-driven wind)

pri. IC

UHE p- pair IC (+UHE Z)

detailed study of cluster emission through simulations warranted

MeV

e+- IC

halo

summary

high energy emission from clusters• primary inverse Compton outskirts, MeV-GeV• p-p 0 core, GeV-TeV• p-p e+- core, MeV• UHE p (+UHE nuclei) photopair emission outskirts, MeV+TeV• cascade emission (pair halo, background) larger scales, GeV-TeV

different components dominate at MeV, GeV, TeVmerger and accretion shock contribute different spectra

probe of structure formation, non-gravitational effects

potentially very rich informationfertile new field of high energy astrophysics!

Inoue & Nagashima; Inoue, Nagashima & Völk, in prep.