(Review) K. Ioka (Osaka U.) 1.Short review of GRBs 2.HE from GRB 3.HE from Afterglow 4.Summary Gamma-Ray Burst Brightest object ergs s -1 Vela satellites (1967) Origin has been a puzzle GRB Spectrum Band spectrum Non-thermal Angular Distribution Isotropic 1000 events/yr Duration Long-soft Short-hard Long burst Short burst Discovery of Afterglow X-ray Radio Beppo-SAX (1997) Redshift z max =4.5 Optical Redshift 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 Standard Model ? optically thick e + e Central Engine Internal Shock External shock >100 ISM Luminosity Time GRB Afterglow Kinetic energy Shock dissipation Afterglow Model ISM Shock emission Electron Fermi acceleration Magnetic field Internal energyKinetic energy Synchrotron emission Great Success of Model Price et al.(03) Fitting: Synchrotron shock model Sari,Piran& Narayan(98) Panaitescu&Kumar(00) Galama et al.(98) Optical Flash Sari&Piran(99) Zhang et al.(03) ISM Shock emission Jet Jet & Relativistic beaming Relativistic beaming Jet Jet in afterglow Energy, Event rate, Model Break in afterglow Harrison et al.(99) Break time Jet angle Break time Standard Total Energy Frail et al.(01) Bloom et al.(03) Small dispersion Massive Star Origin Massive stellar collapse (Hypernova, Collapsar) Binary NS merger Supernova in afterglow Bloom et al.(99) Hjorth et al.(03) 1st example: SN1998bw-dim GRB980425 Position in host galaxy Bloom,Kulkarni&Djorgovski(02) 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 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, 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 GeV Bursts Hurley et al.(94) GRB >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 50GeV fluence 10MeV but no z Tibet array (>10TeV): superpose 57 bursts: 6 GRAND (>10GeV): GRB971110: 2.7 Milagro (>100GeV): VHE fluenceMeV Tail in GRB Gonzalez et al.(03) One of 26GRBs High energy decays more slowly Photon number index: -1 (hard) Totani(00) Nearby GRBs Kneiske et al.(03) 10 3 events/(3Gpc) 3 /yr 1event/(100Mpc) 3 /30yr Off-axis GRB ? 5GRB (z100 ISM Luminosity Time GRB Afterglow Kinetic energy Shock dissipation 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) Shock Acceleration Time scales Maximum energy Acceleration time Dynamical time Cooling time Synchro SSC Proton synchro 0 decay Vietri(95),Waxman(95) Synchrotron m mm 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) Synchrotron Self-Compton Klein-Nishina : 1-p/2 1/2-p 1/2 Guetta&Granot(03) Synchrotron SSC SSC Luminosity * For fast cooling, U U syn ln (t dyn /t cool ) 1/2 (One zone) SSC Synchro Sari&Esin(01) Ioka(03) Proton Synchrotron Vietri(97),Totani(98) e-synchrotron p-synchrotron proton injection fraction eV protons emit 0 Decay Waxman&Bahcall(97) Vietri(98) MeV eV Synchrotron 0 decay GRB Spectrum Pair creation MeVGeVTeVPeV Electron synchtrotron SSC Proton synchrotron 0 decay External Shock ? optically thick e + e Central Engine Internal Shock External shock >100 ISM Luminosity Time GRB Afterglow Kinetic energy Shock dissipation 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 SSC vs p-synchrotron Zhang&Meszaros(01) (I ): SSCp-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 0 Decay Bottcher&Dermer(98) p-syn, p cascade, e + -syn, 0 decay Low energy: normalize to GRB (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) 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 s: Reverse shock emission Wang et al.(01) 4 IC in Early Afterglow Off-Axis GRB Ioka&Nakamura(01) Fluence Energy -ray X-ray X-Ray Flash (XRF) X-ray -ray Lamb et al.(03) XRF GRB except for small E peak & fluence Distance Indicators Sakamoto et al.(03) Yonetoku et al.(03) GRB spectrum Energy Peak Energy XRF We may select nearby bursts quickly 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