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AGILE Pulsar Observations Alberto Pellizzoni INAF-Osservatorio Astronomico di Cagliari on behalf of the AGILE Team & AGILE Pulsar Working Group. 7th Agile Meeting & The bright Gamma-Ray Sky, Frascati. AGILE Timing Calibrations. 35000 pulsed counts collected from Vela PSR. - PowerPoint PPT Presentation
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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: [email protected]
Maura Pilia: [email protected]