agile pulsar observations alberto pellizzoni inaf-osservatorio astronomico di cagliari

AGILE Pulsar ObservationsAlberto Pellizzoni

INAF-Osservatorio Astronomico di Cagliari

on behalf of theAGILE Team & AGILE Pulsar Working Group

7th Agile Meeting & The bright Gamma-Ray Sky, Frascati

AGILE Timing Calibrations

35000 pulsed counts collected from Vela PSR.

5000 ToAs from radio observations by Hobart radiotelescope (Tasmania).

PGAMMA-PRADIO<10-12 s

measured timing resolution=100 s

AGILE vs. FERMI

Fermi

EGRET

AGILE

Fermi

EGRET

AGILE

>0.5 GeV Fermi sensitivity much better than AGILE.at 100 MeV (and below) AGILE sensitivity is competitive.

Vela PSR Observed by Fermi (Abdo et al., 2009)

32400 pulsed counts in 75 days observation time

Vela PSR Observed by AGILE (Pellizzoni et al., 2009 + updates)

35000 pulsed counts in about 100 days observation time

AGILE counts = Fermi x 10

AGILE counts = Fermi

Fermi counts = AGILE x 10

Multi- pulsar observations

AGILE Pulsar Working Group:AGILE Team & ASDC (PSR SW development and Data Analysis):

A.Pellizzoni (chair), M.Pilia, A.Trois, P.Santolamazza, F.Verrecchia (ASDC), F.Fuschino (MCAL),

E.DelMonte (SuperAGILE), A.Chen, A.Giuliani, P.Caraveo, S.Mereghetti … + other collaborators from the AGILE Galactic WG.

Radio-astronomers:

A.Possenti, M.Burgay, M.Kramer, P.Weltevrede, S.Johnston, A.Hotan, J.Palfreyman, I.Cognard, A.Lyne, J.Halpern, A.Corongiu, G.Hobbs, R.N. Manchester

X-rays: P.Esposito, A.DeLuca.

Radiotelescopes:European Pulsar Timing Array (Jodrell Bank, Nancay),Australia Telescope National Facility (Parkes) & Un. Of Tasmania

(Mt.Pleasant)

Michael KramerChiang Mai- 28 June 2005

EPTA partners

The European Pulsar Timing Array

UK - JBCA/University of Manchester DE - MPIfRNL - UvA/ASTRON FR - Nancay/CNRSIT - INAF Cagliari, Sardinia

SRT

Parkes, AustraliaHobart, Tasmania

GBT, West Virginia

Sardinia Radio Telescope (64 m dish) by INAF & ASIwill start pulsar observations in 2010

VelaCrab

Geminga

J1709-4429

J1057-5226J1952+3252

Known Gamma-ray Pulsars (E>100 MeV)

AGILE data on 12 Pulsars published so far including >40% of AGILE Team pulsar

targets (AO1 & AO2)

VELACRAB

GEMINGAB1706-44J2021+3651

J2229+6114B1509-58

B1821-24

J1016-5857

J1357-6429J2043+2740

J1524-5625

J0737-3039

AGILE Pulsars… two years after…

AGILE detected about 20 gamma-ray pulsars

“High-Resolution Timing Observations of Spin-Powered Pulsars with the AGILE gamma-ray

Telescope” (Pellizzoni et al., ApJ, 691, 1618, 2009)

July 2007 – April 2008 DATA

VELA CRAB

GEMINGAB1706-44

AGILE Pulsars… two years after…

…a 16-pages long paper also describing pulsar timing calibration and new tools aimed at precise photon phasing

1 ms

Timing noise uncorrected

Timing noise corrected

Pellizzoni et al. 2009

Hobbs et al. 2004

Pellizzoni et al. 2009

Timing noise uncorrected (dashed)

Timing noise corrected

No light-curve “smearing” even in very long observations

Crab PSR

1 ms

Timing noise uncorrected

Timing noise corrected

High sampling rate of ToAs required…

Fierro et al., 1998

Vela PSR by EGRET

E>1 GeV

E>100 MeV0.9 ms res.

30<E<100 MeV

Radio

Vela

P2 a-b complex

Pellizzoni et al. 2009

P1

P3

P2

P1

P3

P2

E > 1 GeV

E < 100 MeV

P3

0.5<E<30 GeVAGILEE>100 MeV0.7 ms bins

SuperAGILE18-60 keV

Radio

?

Crab

Pellizzoni et al. 2009

(Moffet & Hankins; 1996, 1999)

P3 is coincident with the feature HFC2 that appears in the radio profile above 4 GHz.HFC2 polarization suggest that this peak may come from a lower emission region, near polar cap (Moffet & Hankins; 1996, 1999)

3.7

Crab

Pellizzoni et al. 2009

P3: low altitude cascades?

P1-P2: High-altitude gap (MAGIC)?

(The Magic Collaboration, 2008Sci...322.1221C)

MAGIC

AGILEP3: low altitude cascades?

P3 from Giant Pulses?

We can tag GPs from radio observations and fold at high-energy GPs events only…

Crab

Pellizzoni et al. 2009

E>1 GeV

E>100 MeV2.4 ms

30<E<100 MeV

X-rays (XMM)2-10 keV

complex?

Geminga

Pellizzoni et al. 2009

B1706-44

E>30 MeV2.6 ms

Pellizzoni et al. 2009

Structured energy-dependent peaks (more than two) are evident in the light curves.

How many particle acceleration sites in the pulsars magnetospheres? And where?

Multiple gap models may be invoked… find more in Pellizzoni et al., 2009.

Acceleration gap sizes are related to the width of light-curve peaks?

The theoretical width of a light-curve peak associated with an infinitely small gap would be t=P/2<1 s (typically). Therefore, the width of the apex of the peak can be related to the core gap size.

Gap location Magnetic field Gap size Peak widthBroad peak: outer region, narrow peak: inner region

Ten(s) kilometers

1 km or less

Acceleration gap sizes are related to the width of light-curve peaks?

...pulsar science topics: challenges

High resolution timing of known gamma-ray pulsars (precise phase-aligned multifrequency light curves).

Looking for spectral cut-off and breaks (e.g. in highly magnetized pulsars).

Detection of possible secular variations of the gamma-ray emission from neutron star magnetospheres.

Unpulsed -ray emission from plerions in supernova remnants and searching for time variability of pulsar wind/nebula interactions (e.g. Crab).

Exploiting low energy data (<100 MeV). At E=50-80 MeV angular resolution is poor but large effective area and large number of counts

Gamma-ray emission from pulsar glitches?

• About 6% of pulsars are known to show glitches (/ 10-9-10-6) with a higher incidence of events in younger pulsars.

• Glitches = Starquakes due to exchange of angular momentum between the superfluid neutron star core and its normal solid crust?

• Starquake waves can “shake” magnetic fields generating strong electric fields which accelerate particles to relativistic energies, possibly emitting a burst of high-energy radiation (Ruderman, 1976, 1991; Alpar et al., 1994).

IEE rotglitch24

Gamma-ray emission from pulsar glitches?

• Vela has shown 10 major glitches since 1969.

• The chance occurrence of a strong Vela glitch in the wide AGILE field of view over three years of mission is 20%.

• Expected AGILE gamma-ray counts from a Vela glitch:

where is the unknown conversion efficiency of the glitch energy to gamma-ray emission (Pellizzoni et al., 2009)

11

2 104 Ed

AEC effglitchglitch

Weak:=10-9 : <100 CountsStrong:=10-6 : <105 Counts

Gamma-ray emission from pulsar glitches?

• During early AGILE observations, Vela experienced a weak glitch clearly detected in radio as a discontinuity in the pulsar’s spin parameters

• Expected AGILE gamma-ray counts from a Vela glitch:

where is the unknown conversion efficiency of the glitch energy to gamma-ray emission (Pellizzoni et al., 2009)

11

2 104 Ed

AEC effglitchglitch

Weak:=10-9 : <100 CountsStrong:=10-6 : <105 Counts

Small Vela glitch in August 2007: burst emission possibly detected by AGILE

Vela glitch=54,312.5+/-3 MJDE>

50 M

eV

15 photons in 4 minutes

Cglitch=1011 counts

NEW GAMMA-RAY PULSARS!

“Discovery of New Gamma-ray Pulsars with AGILE”(Pellizzoni et al., ApJ, 695, L115, 2009)

July 2007 – June 2008

J2229+6114B1509-58

B1821-24

J1016-5857

J1357-6429J2043+2740

J1524-5625

AGILE Pulsars… two years after…

Many previously unidentified EGRET sources and new AGILE sources are Pulsars!

New Gamma-Ray PulsarsJ2229+6114, J2021+3651, …: Vela-like

B1509-58: High B pulsar

B1821-24 : ms PSR in Globular Cluster----------------------------------J1016-5857: possibly 3EG source

J1357-6429

J2043+2740: oldest gamma-ray pulsar

J1524-5625

Pellizzoni et al., 2009

PSR J2229+6114

Pilia et al., in preparation

PSR J2229+6114

Pilia et al., in preparation

New Gamma-Ray PulsarsJ2229+6114, J2021+3651, …: Vela-like

B1509-58 : High B pulsar

B1821-24 : ms PSR in Globular Cluster----------------------------------J1016-5857: possibly 3EG source

J1357-6429

J2043+2740: oldest gamma-ray pulsar

J1524-5625

Pellizzoni et al., 2009

B1509 -58 by COMPTEL (Kuiper et al., 1999)

COMPTEL

AGILE detection both in timing and likelihood analysis >4

Two gamma-ray peak with different spectra (P1 “soft”, P2 “hard”)

AGILE

P1 P2

B1509 -58 by COMPTEL (Kuiper et al., 1999)

P1P2

B1509-58: multi-gap model… under construction!

AGILE

COMPTEL

EGRET (upper limits)

(Harding et al.,1997)

B > 10^13 Gauss:photon splitting (!)

P1 ?

P2 ?

New Gamma-Ray PulsarsJ2229+6114, J2021+3651, …: Vela-like

B1509-58 : High B pulsar

B1821-24: ms PSR in Globular Cluster----------------------------------J1016-5857: possibly 3EG source

J1357-6429

J2043+2740: oldest gamma-ray pulsar

J1524-5625

Pellizzoni et al., 2009

A new (variable??) millisecond gamma-ray pulsar in a globular cluster

EROT= 2.2x1036 erg/sP = 3 msd = 4.9 kpc

New gamma-ray pulsars being discovered also by AGILE Guest Observers

(Halpern et al., ApJ, 688, L33, 2008)

J2229+6114B1509-58

B1821-24

J1016-5857

J1357-6429J2043+2740

J1524-5625

AGILE Pulsars… two years after…

J2021+3651

See http://agile.asdc.asi.it for details about AGILE Guest Observer Programs

Halpern et al., 2008

Radio PSRs candidates as strong gamma-ray emitters (Pellizzoni et al., 2004)

>50 (new) candidates with expected fluxes > 5x10-8 ph/cm2/s @ E>100 MeV

ROTEkL

Future plans:-The search for new gamma-ray pulsars is a non-stop job.- Full exploitation of <100 MeV band (exposure competitive with Fermi)- Phase-resolved spectra of bright gamma-ray pulsars.- “Blind-search” of “soft” radio-quiet pulsars.- Gamma-rays from pulsars in binary systems.

Double neutron star system 0737-

3039

Orbital period: 2.4 h

eccentricity=0.09

(Burgay et al., 2003; Lyne et al.,

2004)

Pellizzoni et al., 2008

Double neutron star system 0737-

3039

Orbital period: 2.4 h

eccentricity=0.09

(Burgay et al., 2003)

PSR B

PSR A

OBSERVER

Double neutron star system 0737-

3039

Orbital period: 2.4 h

eccentricity=0.09System observed nearly edge-on

PSRs separation 3 light seconds

3 light seconds

PSR A: P=22.7 ms EROT=6x1033 erg/s,

=210 MyrB=6.3x109 G1.337 MSOL

PSR B: P=2.7 s EROT=2x1030 erg/s

=50 MyrB=1.2x1012 G

1.25 MSOL

PSR B

PSR A

Lyne et al., 2004

ROTE

PSR B

PSR A

Wind/magnetosp.pressure of a companion NS:

REQ < system separ. REQ < 103 RLCA REQ < 10 RLCB

Pellizzoni et al., 2008

PRELIMINARYPellizzoni et al., in prep.

Thank You!

For information and collaborations, please contact us:

Alberto Pellizzoni: apellizz@ca.astro.it

Maura Pilia: mpilia@ca.astro.it