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). P GAMMA -P RADIO <10 -12 s measured timing resolution=100  s

4. AGILE vs. FERMI

5. Fermi EGRET AGILE

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

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

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

11. Multi- pulsar observations

12. 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)

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

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

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

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

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

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

19. 1 ms Timing noise uncorrected Timing noise corrected Pellizzoni et al. 2009

20. Hobbs et al. 2004 Pellizzoni et al. 2009

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

22. 1 ms Timing noise uncorrected Timing noise corrected High sampling rate of ToAs required…

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

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

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

26. E < 100 MeV P3

27. 0.5<E<30 GeV AGILE E>100 MeV  0.7 ms bins SuperAGILE 18-60 keV Radio ? Crab Pellizzoni et al. 2009

28. (Moffet & Hankins; 1996, 1999)

29. 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?

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

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

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

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

34. 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.

35. 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 width Broad peak: outer region, narrow peak: inner region

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

37. ...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

38. 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).

39. 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) Weak:  =10 -9 : <100 Counts Strong:  =10 -6 : <10 5 Counts

40. 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) Weak:  =10 -9 : <100 Counts Strong:  =10 -6 : <10 5 Counts

41. Small Vela glitch in August 2007: burst emission possibly detected by AGILE Vela glitch=54,312.5+/-3 MJD E>50 MeV 15 photons in 4 minutes C  glitch =10 11   counts   

42. NEW GAMMA-RAY PULSARS!

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

44. 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 Pellizzoni et al., 2009

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

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

47. 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 Pellizzoni et al., 2009

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

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

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

51. B1509-58: multi-gap model… under construction! AGILE COMPTEL EGRET (upper limits) (Harding et al.,1997) B > 10^13 Gauss: photon splitting (!) P1 ? P2 ?

53. 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 Pellizzoni et al., 2009

54. A new (variable??) millisecond gamma-ray pulsar in a globular cluster E ROT = 2.2x10 36 erg/s P = 3 ms d = 4.9 kpc

55. New gamma-ray pulsars being discovered also by AGILE Guest Observers (Halpern et al., ApJ, 688, L33, 2008) J2229+6114 B1509-58 B1821-24 J1016-5857 J1357-6429 J2043+2740 J1524-5625 AGILE Pulsars… two years after… J2021+3651 See http://agile.asdc.asi.it for details about AGILE Guest Observer Programshttp://agile.asdc.asi.it

56. Halpern et al., 2008

57. Radio PSRs candidates as strong gamma-ray emitters (Pellizzoni et al., 2004) >50 (new) candidates with expected fluxes > 5x10 -8 ph/cm 2 /s @ E>100 MeV

58. 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.

59. 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

60. Double neutron star system 0737-3039 Orbital period: 2.4 h eccentricity=0.09 (Burgay et al., 2003)

61. PSR B PSR A OBSERVER Double neutron star system 0737-3039 Orbital period: 2.4 h eccentricity=0.09 System observed nearly edge-on PSRs separation 3 light seconds  3 light seconds 

62. PSR A: P=22.7 ms E ROT =6x10 33 erg/s,  =210 Myr B=6.3x10 9 G 1.337 M SOL PSR B: P=2.7 s E ROT =2x10 30 erg/s  =50 Myr B=1.2x10 12 G 1.25 M SOL PSR B PSR A Lyne et al., 2004

63. PSR B PSR A Wind/magnetosp. pressure of a companion NS: R EQ < system separ. R EQ < 10 3 R LCA R EQ < 10 R LCB Pellizzoni et al., 2008

64. PRELIMINARY Pellizzoni et al., in prep.

65. Thank You! For information and collaborations, please contact us: Alberto Pellizzoni: apellizz@ca.astro.itapellizz@ca.astro.it Maura Pilia: mpilia@ca.astro.itmpilia@ca.astro.it