1. (Review) K. Ioka (Osaka U.) 1.Short review of GRBs 2.HE  from GRB 3.HE  from Afterglow 4.Summary

2. Gamma-Ray Burst Brightest object ～ 10 52 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 X-ray Radio Beppo-SAX (1997)

7. Redshift z max =4.5 Optical → Redshift

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

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

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

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

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

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

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

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

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

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

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

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

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

21. Short Summary 1.Cosmological (Long GRBs) 2.Relativistic jet is ejected:  >100 3.Internal shock: GRB 4.External forward shock: Afterglow 5.External reverse shock: Optical flash 6.Synchrotron shock model succeeds 7.Standard total energy (?) 8.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, HE, HE , GW ?  GRBs & cosmology: How to use ? Etc …

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

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

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

26. Totani(00) ⇒ Nearby GRBs Kneiske et al.(03) 10 3 events/(3Gpc) 3 /yr ～ 1event/(100Mpc) 3 /30yr ⇒ Off-axis GRB ? 5GRB (z<0.5) IR Background

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

28. e ± Pair Creation Target photon energy Cutoff energy N photon ～ 200keV  ⇒ Dim or long timescale bursts for TeV ＊ Scattering constraint is stronger if  <  m e c 2 TeV N target  target Lithwick&Sari(01)

29. Shock Acceleration Time scales Maximum energy ① Acceleration time ② Dynamical time ③ Cooling time ⇒ ① Synchro ② SSC ③ Proton synchro ④  0 decay Vietri(95),Waxman(95)

30. Synchrotron m mm  max max ∝  e -p ∝  e -p-1 ∝  e -2 ∝ (2-p)/2 ∝ 1/2 Electron energy spectrum Photon spectrum Dim or long burst: X-ray flash ? Sari,Piran &Narayan(98)

31. Synchrotron Self-Compton Klein-Nishina : ∝ 1-p/2 ∝ 1/2-p ∝ 1/2 Guetta&Granot(03) Synchrotron SSC

32. SSC Luminosity * For fast cooling, U  ～ U syn ×ln (t dyn /t cool ) 1/2 (One zone) SSC ～ Synchro Sari&Esin(01) Ioka(03)

33. Proton Synchrotron Vietri(97),Totani(98) e-synchrotron p-synchrotron proton injection fraction ～ 10 20 eV protons emit

34.  0 Decay Waxman&Bahcall(97) Vietri(98) ～ MeV ～ 10 15 eV Synchrotron  0 decay

35. GRB Spectrum Pair creation MeVGeVTeVPeV Electron synchtrotron SSC Proton synchrotron  0 decay

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

37. e,p-synchrotron & SSC Zhang&Meszaros(01) Long-dash: e-sy, short-dash: p-sy, dots: SSC Times: trigger, 1 min, 1 hr, 1day, 1 month E 52 =1, p=2.2,  p =1,  0 =300, z=1 flat  e =10 -3,  B =0.5 n=100 cm -3  e =0.5,  B =0.01 n=1 cm -3  e =0.01,  B =0.1 n=1 cm -3 p-sy SSC e-sy

38. SSC vs p-synchrotron Zhang&Meszaros(01) (I ’ ): SSC<p-syn (II ’ ): SSC>p-syn for TeV SSC dominates in typical afterglow U p ～ U e,E 52 =1,n=1 p=2.2,t=1hr p-sy SSC

39.  0 Decay Bottcher&Dermer(98) p-syn, p  cascade, e + -syn,  0 decay Low energy: normalize to GRB970508 (z=0.83) E 52 =1, n=1 cm -3,  0 =300,  p =1,  B =1, p=2 Cascade emission decays more slowly than SSC (protons have less cooling)

40. E 53 =1,  e =0.6,  B =0.01,p=2.5E 52 =1,  e =0.6,  B =0.01,p=2.5 E 53 =1,  e =0.6,  B =10 -4,p=2.5 E 53 =1,  e =0.6,  B =0.01,p=2.2 f-syn r-syn solid: r-SSC dot: f-SSC dash-dot: f-IC of r dash: r-IC of f 10-100s: Reverse shock emission Wang et al.(01) 4 IC in Early Afterglow

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

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

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

44. Summary IR background ⇒ Nearby bursts for TeV Afterglow is better than GRB for TeV High energy ～ Low energy SSC, p-Synchrotron,  0 decay, etc. ⇒ Physical state, Lorentz factor, etc. Nearby bursts ～ Off-axis ～ X-ray flash(?) Distance indicators ⇒ Nearby bursts