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ガンマ線バーストからの 高エネルギーガンマ線

ガンマ線バーストからの 高エネルギーガンマ線. (Review). K. Ioka (Osaka U.). Short review of GRBs HE g from GRB HE g from Afterglow Summary. Gamma-Ray Burst. Brightest object ～ 10 52 ergs s -1. Vela satellites (1967). Origin has been a puzzle. GRB Spectrum. Band spectrum. Non-thermal.

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ガンマ線バーストからの 高エネルギーガンマ線

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  1. ガンマ線バーストからの 高エネルギーガンマ線 (Review) K. Ioka (Osaka U.) • Short review of GRBs • HEg from GRB • HEg from Afterglow • Summary

  2. Gamma-Ray Burst Brightest object ～1052 ergs s-1 Vela satellites (1967) Origin has been a puzzle

  3. GRB Spectrum Band spectrum Non-thermal

  4. Angular Distribution Isotropic ～1000 events/yr

  5. Duration Long-soft Short-hard Long burst Short burst

  6. Discovery of Afterglow Beppo-SAX (1997) X-ray Radio

  7. Redshift Optical → Redshift zmax=4.5

  8. Summary of Observation >msec Luminosity Redshift Afterglow GRB X-ray Optical Radio ～1000 events/yr Isotropic, Inhomogeneous ～200 keV, Non-thermal 10-3s～103s : short, long Time

  9. Standard Model optically thick gg→e+e- Internal Shock ? ISM G>100 Central Engine External shock Luminosity Kinetic energy ↓ Shock dissipation GRB Afterglow Time

  10. Afterglow Model ISM Shock emission ｒｅｖｅｒｓｅ ｓｈｏｃｋ ｆｏｒｗａｒｄ ｓｈｏｃｋ Kinetic energy Internal energy ① Electron Fermi acceleration ② Magnetic field ⇒ Synchrotron emission

  11. Great Success of Model Synchrotron shock model Sari,Piran& Narayan(98) Price et al.(03) Fitting:

  12. Panaitescu&Kumar(00) Galama et al.(98)

  13. Optical Flash ISM Shock emission ｒｅｖｅｒｓｅ ｓｈｏｃｋ ｆｏｒｗａｒｄ ｓｈｏｃｋ Zhang et al.(03) Sari&Piran(99)

  14. Jet Jet & Relativistic beaming ・ Relativistic beaming ・ Jet Energy, Event rate, Model Jet in afterglow ：ｓｉｄｅｗａｙｓ ｅｘｐａｎｓｉｏｎ

  15. Break in afterglow Break time ⇒ Jet angle Harrison et al.(99) Break time

  16. Standard Total Energy Bloom et al.(03) Small dispersion Frail et al.(01)

  17. Massive Star Origin Binary NS merger Massive stellar collapse (Hypernova, Collapsar)

  18. Supernova in afterglow 1st example: SN1998bw-dim GRB980425 Hjorth et al.(03) Bloom et al.(99)

  19. Position in host galaxy Bloom,Kulkarni&Djorgovski(02)

  20. GRB Cosmology Massive star origin ⇒ High redshift GRBs Like QSO Like SN Star formation Microlensing Reionization … GRB Larson&Bromm(02) GRBs are useful for probing high z QSO, galaxy

  21. Short Summary • Cosmological (Long GRBs) • Relativistic jet is ejected: G>100 • Internal shock: GRB • External forward shock: Afterglow • External reverse shock: Optical flash • Synchrotron shock model succeeds • Standard total energy (?) • Massive star origin (Long GRBs) But, …

  22. Problems Fireball content: Kinetic or magnetic ? GRB emission mechanism: Synchro or not ? GRB jet structure: Uniform or not ? Jet acceleration: How to launch ? Environment: What is in front ? Shock parameters: Universal or not ? Short GRBs: What ? Other emissions: UHECR, HEn, HEg, GW ? GRBs & cosmology: How to use ? Etc…

  23. GeV Bursts GRB940217 18GeV Hurley et al.(94) Earth occultation 90min GeV at 2.4s and 25s Spectral index –2 to GeV >MeV energy～<MeV one Sommer et al.(94) >10GeV photons can last for > 1hr GeV burst starts with MeV 2% of total energy at 30MeV-20GeV EGRET: 7GRB (100MeV<n<18GeV)

  24. Possible TeV Bursts Milagrito: Tentative (3s) TeV detection in 54 bursts >50GeV fluence～10×MeV but no z Tibet array (>10TeV): superpose 57 bursts: 6s GRAND (>10GeV): GRB971110: 2.7s Milagro (>100GeV): VHE fluence<MeV one GRB970417a a-ph/0311389 Atkins et al.(00)

  25. >MeV Tail in GRB941017 One of 26GRBs High energy decays more slowly Photon number index: -1 (hard) Gonzalez et al.(03)

  26. IR Background Totani(00) Kneiske et al.(03) 5GRB (z<0.5) 103events/(3Gpc)3/yr ～1event/(100Mpc)3/30yr ⇒ Off-axis GRB ? ⇒ Nearby GRBs

  27. Internal Shock optically thick gg→e+e- Internal Shock ? ISM G>100 Central Engine External shock Luminosity Kinetic energy ↓ Shock dissipation GRB Afterglow Time

  28. e± Pair Creation Target photon energy Nphoton ～200keV Cutoff energy TeV Ntarget Lithwick&Sari(01) n ntarget ngg ⇒ ⇒ Dim or long timescale bursts for TeV ＊Scattering constraint is stronger ifngg<Gmec2

  29. Shock Acceleration Time scales ① Acceleration time ② Dynamical time ③ Cooling time Maximum energy Vietri(95),Waxman(95) ⇒ ①Synchro ②SSC ③Proton synchro ④p0 decay

  30. Electron energy spectrum Synchrotron ∝ge-p ∝ge-2 gm gmax ∝ge-p-1 Photon spectrum nm nmax ∝n(2-p)/2 ∝n1/2 Dim or long burst: X-ray flash ? Sari,Piran &Narayan(98)

  31. Synchrotron Self-Compton SSC ∝n1-p/2 ∝n1/2-p Synchrotron ∝n1/2 Guetta&Granot(03) Klein-Nishina:

  32. SSC Luminosity (One zone) Sari&Esin(01) SSC～Synchro * For fast cooling, Ug～Usyn×ln (tdyn/tcool)1/2 Ioka(03)

  33. Proton Synchrotron Vietri(97),Totani(98) e-synchrotron p-synchrotron ～1020eV protons emit proton injection fraction

  34. Waxman&Bahcall(97) Vietri(98) p0 Decay Synchrotron p0 decay ～MeV ～1015eV

  35. GRB Spectrum Pair creation Proton synchrotron Electron synchtrotron SSC p0 decay MeV GeV TeV PeV

  36. External Shock optically thick gg→e+e- Internal Shock ? ISM G>100 Central Engine External shock Luminosity Kinetic energy ↓ Shock dissipation GRB Afterglow Time

  37. e,p-synchrotron & SSC p-sy e-sy SSC ee=10-3, eB=0.5 n=100 cm-3 ee=0.5, eB=0.01 n=1 cm-3 ee=0.01, eB=0.1 n=1 cm-3 Long-dash: e-sy, short-dash: p-sy, dots: SSC Times: trigger, 1 min, 1 hr, 1day, 1 month E52=1, p=2.2, ep=1, G0=300, z=1 flat Zhang&Meszaros(01)

  38. SSC vs p-synchrotron p-sy (I’): SSC<p-syn (II’): SSC>p-syn for TeV SSC dominates in typical afterglow Up～Ue,E52=1,n=1 p=2.2,t=1hr SSC Zhang&Meszaros(01)

  39. p0 Decay p-syn, pg cascade, e+-syn, p0 decay Low energy: normalize to GRB970508 (z=0.83) E52=1, n=1 cm-3, G0=300, ep=1, eB=1, p=2 Cascade emission decays more slowly than SSC (protons have less cooling) Bottcher&Dermer(98)

  40. 4 IC in Early Afterglow 10-100s: Reverse shock emission E53=1,ee=0.6,eB=0.01,p=2.5 E52=1,ee=0.6,eB=0.01,p=2.5 f-syn r-syn solid: r-SSC dot: f-SSC dash-dot: f-IC of r dash: r-IC of f E53=1,ee=0.6,eB=10-4,p=2.5 E53=1,ee=0.6,eB=0.01,p=2.2 Wang et al.(01)

  41. Off-Axis GRB Fluence g-ray X-ray Energy Ioka&Nakamura(01)

  42. X-Ray Flash (XRF) Lamb et al.(03) X-ray XRF～GRB except for small Epeak & fluence g-ray

  43. Distance Indicators XRF Yonetoku et al.(03) Sakamoto et al.(03) We may select nearby bursts quickly Peak Energy GRB spectrum Energy

  44. Summary IR background ⇒ Nearby burstsfor TeV Afterglowis better than GRB for TeV High energy ～ Low energy SSC, p-Synchrotron, p0 decay, etc. ⇒ Physical state, Lorentz factor, etc. Nearbybursts～Off-axis～X-rayflash(?) Distance indicators⇒ Nearby bursts

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