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AGILE Pulsar Observations Alberto Pellizzoni INAF-Osservatorio Astronomico di Cagliari

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.

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AGILE Pulsar Observations Alberto Pellizzoni INAF-Osservatorio Astronomico di Cagliari

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  1. 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

  2. AGILE Timing Calibrations

  3. 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 ms

  4. AGILE vs. FERMI

  5. Fermi EGRET AGILE

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

  7. Vela PSR Observed by Fermi (Abdo et al., 2009) 32400 pulsed counts in 75 days observation time

  8. Vela PSR Observed by AGILE (Pellizzoni et al., 2009 + updates) 35000 pulsed counts in about 100 days observation time

  9. AGILE counts = Fermi x 10 AGILE counts = Fermi Fermi counts = AGILE x 10

  10. Multi-l pulsar observations

  11. 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)

  12. EPTA partners The European Pulsar Timing Array UK - JBCA/University of Manchester DE - MPIfR NL - UvA/ASTRON FR - Nancay/CNRS IT - INAF Cagliari, Sardinia Michael Kramer Chiang Mai- 28 June 2005 SRT

  13. Parkes, Australia Hobart, Tasmania GBT, West Virginia

  14. Sardinia Radio Telescope (64 m dish) by INAF & ASI will start pulsar observations in 2010

  15. Known Gamma-ray Pulsars (E>100 MeV) J1057-5226 J1952+3252 Geminga Crab J1709-4429 Vela

  16. AGILE Pulsars… two years after… AGILE detected about 20 gamma-ray pulsars J1524-5625 GEMINGA J2229+6114 J2021+3651 B1509-58 J1016-5857 B1706-44 J0737-3039 J1357-6429 VELA B1821-24 CRAB J2043+2740 AGILE data on 12 Pulsars published so far including >40% of AGILE Team pulsar targets (AO1 & AO2)

  17. AGILE Pulsars… two years after… “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 GEMINGA B1706-44 VELA CRAB …a 16-pages long paper also describing pulsar timing calibration and new tools aimed at precise photon phasing

  18. Timing noise uncorrected Timing noise corrected 1 ms Pellizzoni et al. 2009

  19. Hobbs et al. 2004 Pellizzoni et al. 2009

  20. Crab PSR Timing noise corrected Timing noise uncorrected (dashed) No light-curve “smearing” even in very long observations

  21. Timing noise uncorrected Timing noise corrected 1 ms High sampling rate of ToAs required…

  22. Vela PSR by EGRET Fierro et al., 1998

  23. Vela E>1 GeV E>100 MeV 0.9 ms res. 30<E<100 MeV Radio P2 a-b complex Pellizzoni et al. 2009

  24. E > 1 GeV P2 P2 P1 P1 P3 P3

  25. E < 100 MeV P3

  26. Crab 0.5<E<30 GeV AGILE E>100 MeV 0.7 ms bins SuperAGILE 18-60 keV Radio ? Pellizzoni et al. 2009

  27. (Moffet & Hankins; 1996, 1999)

  28. Crab 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) 3.7s P3: low altitude cascades? Pellizzoni et al. 2009

  29. (The Magic Collaboration, 2008Sci...322.1221C) MAGIC P3: low altitude cascades? AGILE P1-P2: High-altitude gap (MAGIC)?

  30. Crab P3 from Giant Pulses? We can tag GPs from radio observations and fold at high-energy GPs events only… Pellizzoni et al. 2009

  31. E>1 GeV E>100 MeV 2.4 ms 30<E<100 MeV X-rays (XMM) 2-10 keV Geminga complex? Pellizzoni et al. 2009

  32. B1706-44 E>30 MeV 2.6 ms Pellizzoni et al. 2009

  33. 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.

  34. 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 Dt=P/2pG, <1 ms (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 width Broad peak: outer region, narrow peak: inner region

  35. Acceleration gap sizes are related to the width of light-curve peaks? Ten(s) kilometers 1 km or less

  36. ...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 g-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

  37. Gamma-ray emission from pulsar glitches? • About 6% of pulsars are known to show glitches (Dn/n 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).

  38. 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 h is the unknown conversion efficiency of the glitch energy to gamma-ray emission (Pellizzoni et al., 2009) Weak: Dn/n=10-9 : <100 Counts Strong: Dn/n=10-6 : <105 Counts

  39. 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 h is the unknown conversion efficiency of the glitch energy to gamma-ray emission (Pellizzoni et al., 2009) Weak: Dn/n=10-9 : <100 Counts Strong: Dn/n=10-6 : <105 Counts

  40. Vela glitch=54,312.5+/-3 MJD Cgglitch=1011hDn/n counts Dn/n=10-9 h=0.1 15 photons in 4 minutes E>50 MeV Small Vela glitch in August 2007: burst emission possibly detected by AGILE

  41. NEW GAMMA-RAY PULSARS!

  42. AGILE Pulsars… two years after… “Discovery of New Gamma-ray Pulsars with AGILE” (Pellizzoni et al., ApJ, 695, L115, 2009) July 2007 – June 2008 J1524-5625 J2229+6114 B1509-58 J1016-5857 J1357-6429 B1821-24 J2043+2740 Many previously unidentified EGRET sources and new AGILE sources are Pulsars!

  43. Pellizzoni et al., 2009 New Gamma-Ray Pulsars J2229+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

  44. PSR J2229+6114 Pilia et al., in preparation

  45. PSR J2229+6114 Pilia et al., in preparation

  46. Pellizzoni et al., 2009 New Gamma-Ray Pulsars J2229+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

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

  48. COMPTEL AGILE P1 P2 AGILE detection both in timing and likelihood analysis >4s Two gamma-ray peak with different spectra (P1 “soft”, P2 “hard”)

  49. B1509 -58 by COMPTEL (Kuiper et al., 1999) P1 P2

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