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EMISSIONE GAMMA DA PULSARS E PULSARS WIND NEBULAE A. Pellizzoni – AGILE Team – INAF/IASF Milano

EMISSIONE GAMMA DA PULSARS E PULSARS WIND NEBULAE A. Pellizzoni – AGILE Team – INAF/IASF Milano. GLAST (future). EGRET (past). AGILE (present). Radio pulsars (>1700). Gamma-rays , X-rays , optical , radio, EGRET unidentified. ~7 (+8?) Spin-Powered Pulsars detected in Gamma-rays. ms.

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EMISSIONE GAMMA DA PULSARS E PULSARS WIND NEBULAE A. Pellizzoni – AGILE Team – INAF/IASF Milano

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  1. EMISSIONE GAMMA DA PULSARS E PULSARS WIND NEBULAE A. Pellizzoni – AGILE Team – INAF/IASF Milano

  2. GLAST (future) EGRET (past) AGILE (present)

  3. Radio pulsars (>1700) Gamma-rays, X-rays, optical, radio, EGRET unidentified

  4. ~7 (+8?) Spin-Powered Pulsars detected in Gamma-rays ms

  5. Millisecond Region Gamma-Ray Pulsar Region

  6. Vela-like (not too far) “normal” (close) Millisecond Region Gamma-Ray Pulsar Region

  7. Crab B1706-44 Vela B1055-52 Geminga

  8. 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 AGILE is expected to discover 10-15 new gamma-ray PSRs… GLAST much more

  9. Gonthier, Guilder & Harding, 2004, ApJ, 604, 775

  10. 15-20 known gamma-PSRs and candidates in a single poiting L=310-320

  11. Long term monitoring of known gamma-ray pulsars • Discovery of gamma-ray emission from near and young pulsars discovered after the end of CGRO. • Unidentified non-variable EGRET sources (better positioning, secular variability, period searches). How many radio-quiet pulsars? • Gamma-ray emission from millisecond pulsars (beyond J0218+4232...).

  12. ...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

  13. PULSARS Most of PSR spin-down energy EROT (1035-1039 erg/s) in pulsar wind (g=106) and high-energy radiation (1-10% EROT)

  14. Looking for E~100 MeV spectral cut-off in highly magnetized pulsars AGILE sensitivity PSR 10 times fainter than 1509-58 Possible cut-off

  15. High resolution timing Typical single pulses from Vela at 1413 Mhz with a time resolution of 44 ms (Johnston et al., APJ, 549, L101)

  16. PULSARS Most of PSR spin-down energy EROT (1035-1039 erg/s) in pulsar wind (g=106) and high-energy radiation (1-10% EROT)

  17. PULSAR WIND PRESSURE Most of PSR spin-down energy Erot (1035-1039 erg/s) in pulsar wind (g=106) R wind pressure Distance from PSR surface wind pressure PSR

  18. PULSAR WIND PRESSURE Most of PSR spin-down energy Erot (1035-1039 erg/s) in pulsar wind (g=106) external pressure shock wind pressure Distance from PSR surface wind pressure PSR Equilibrium distance At REQ: shock  synchrotron emission (+ IC emission)

  19. Nature/strength of PEXTERNAL ? Typical REQ ? external pressure shock wind pressure Distance from PSR surface wind pressure PSR Equilibrium distance At REQ: shock  synchrotron emission (+ IC emission)  X-rays, gamma-rays, TeV

  20. PEXTERNAL possible origins: • Ram pressure due to supersonic motion (>10 km/s) of the NS in the ISM • Supernova Remnant cold ejecta: static Pulsar Wind Nebulae/plerions (e.g. Crab) • Outflow from a stellar companion (e.g. PSRB1259-63 + Be star, PSRB1957+20 + white dwarf ) • Wind/magnetosphere pressure of a companion NS (DNSB)

  21. PEXTERNAL possible origins and typical REQ: • Ram pressure due to supersonic motion (>10 km/s) of the NS in the ISM • Supernova Remnant cold ejecta: static Pulsar Wind Nebulae/plerions (e.g. Crab) • Outflow from a stellar companion (e.g. PSR B1259-63 + Be star, PSR B1957+20 + white dwarf ) • Wind/magnetosphere pressure of a companion NS (DNSB)  REQ=106-1010 RLC  REQ=106-109 RLC  REQ=104 RLC  REQ=10-103 RLC

  22. PSR wind magnetization parameter: s=Poynting flux/kinetic energy s(R) dependences on pulsar distance s<<1 for REQ=108 RLC as in Crab-like PWN s>>1?? for REQ < 103 RLC as for DNSB as 0737 Shock efficiency prop to 1/sqrt(s), Kennel & Coroniti (1984)

  23. Ram pressure due to supersonic motion of the NS (>10 km/s) in the ISM (optical) "Guitar Nebula" Cordes et al., 1993 Pexternal=rV2: REQ=106-1010 RLC "Comet-shaped" bow-shocks: High pulsar velocity in the Interstellar Medium

  24. Ram pressure due to supersonic motion of the NS (>10 km/s) in the ISM (X-rays) Vtr=120 km/s Tails = ~450 counts L =~2x10-6Erot B= 10-5 G Emax = 1014 eV 30” Pexternal=rV2: REQ=106-1010 RLC "Geminga Tails" Caraveo et al., 2003

  25. Aharonian et al., 2006

  26. Gamma-rays from PSR bow-shocks? Gamma-rays sinchrotron emission at E>50 MeV: Weak dependence on external pressure. Approximately proportional to spin-down energy…  AGILE and GLAST Brightest PSRs: • EGRET UnID? A new significant component for the diffuse gamma-ray emission?

  27. ~85 Non-Variable EGRET Unidentified Sources

  28. SNR cold ejecta pressure: static Pulsar Wind Nebulae/plerions Hester et al., 2002 Crab Pulsar REQ=106-109 RLC Pulsar Wind Nebula

  29. Gamma-ray variability of Crab nebula? 1-month obs. 2-months obs. Crab Nebula

  30. Outflow from a stellar companion (e.g. PSR B1259-63+ Be star, PSR B1957+20 + white dwarf ) REQ=104 RLC Mirabel, 2006

  31. Gamma-ray HMXRB: LS I +61 303, LS 5039 : microquasars or PSR-stellar wind shock mimic jet, EGRET source?, VHE PSR B1259-63: ms pulsar, VHE source, no EGRET counterpart Accretion-powered relativistic jets vs.NS-stellar wind shock AGILE and GLAST will -Verify EGRET associations -Study gamma-ray variability and correlation with radio/X-ray emission -Assess models: HE and VHE emission mechanisms

  32. Broad band spectrum of LS I +61 303 (Sidoli, Pellizzoni, Vercellone et al., 2006)

  33. Broad band spectrum of LS I +61 303 (Sidoli, Pellizzoni, Vercellone et al., 2006) 1-10 MeV break Synchtrotron emission from shock-accelerated particles… ? Acceleration Time = Cooling time

  34. Broad band spectrum of LS I +61 303 (Sidoli, Pellizzoni, Vercellone et al., 2006) No firm EGRET association ?

  35. Broad band spectrum of LS I +61 303 (Sidoli, Pellizzoni, Vercellone et al., 2006) Large error bars ?

  36. Broad band spectrum of LS I +61 303 (Sidoli, Pellizzoni, Vercellone et al., 2006) 1-10 MeV break Synchtrotron emission from shock-accelerated particles CSSR, SSC, pair cascades, hadronic mechanisms?

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

  38. Wind/magnetosp.pressure of a companion NS: PSR B PSR A

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

  40. PSR A: P=22.7 ms EROT=6x1033 erg/s, t=210 Myr B=6.3x109 G 1.337 MSOL PSR B: P=2.7 s EROT=2x1030 erg/s t=50 Myr B=1.2x1012 G 1.25 MSOL PSR B PSR A Lyne et al., 2004

  41. Wind/magnetosp.pressure of a companion NS: PSR B magnetic pressure shock wind pressure wind pressure REQ < system separ. REQ < 103 RLCA REQ < 10 RLCB PSR A

  42. PEXTERNAL(R)? PSR B wind or PSR B magnetosphere pressure? Similar to the interaction between the Earth and the solar wind Lyutikov, 2004 Arons, 2004 Wind pressure (PSR A)=magnetic pressure (PSR B) at REQ=0.2 lt-s from B

  43. PSRs wind/magnetosphere shock  synchrotron emission (+ IC emission)  X-rays/g-rays/TeV • Ram pressure due to supersonic motion (>10 km/s) of the NS in the ISM • Supernova Remnant cold ejecta: static Pulsar Wind Nebulae/plerions (e.g. Crab) • Outflow from a stellar companion (e.g. PSR B1259-63 + Be star, PSR B1957+20 + white dwarf ) • Wind/magnetosphere pressure of a companion NS (DNSB)  REQ=106-1010 RLC  REQ=106-109 RLC  REQ=104 RLC  REQ=10-103 RLC

  44. Aharonian et al., 2006

  45. Gamma-ray astronomers have to be happy but patient e.g.: typical AGILE (GLAST) pulsar targets provide 2-3 (12-20) gamma-ray photon per day (with few exceptions …)

  46. GRAZIE A. Pellizzoni – AGILE Team – INAF/IASF Milano

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