Gamma-Ray Bursts from Radiation-Dominated Jet? Kunihito Ioka (KEK) T. Inoue, Asano & KI, arXiv: KI, arXiv: Suwa & KI, arXiv: KI+, in preparation (arXiv: ) Sorry for changing the title to a preliminary study Comments welcome

Baryon Loading  or r/r 0  =E/Mc 2  * ~10 3  * ~10 3 Photon-to-Baryon Radiation-Dominated Matter- Dominated Paczynski, Goodman Meszaros & Rees Shemi & Piran

Baryon Loading  or r/r 0  =E/Mc 2  * ~10 3  * ~10 3 IS Synchro. Photosphere Original Paczynski Goodman Photon-to-Baryon Compactness Non-thermal Except Zhang & Yan 11, KI 10, Tchekhovskoy+ 10, McKinney 10, Gianinnos+ 07 (& others?) Beloborodov Vurm, Daigne Medvedev, Ryde, Lundman ~10 2

Fermi Revolution GeV  from GRBs GRB Abdo+ 09 GeV MeV keV

Baryon Loading  or r/r 0  =E/Mc 2  * ~10 3  * ~10 3 IS Synchro. Photosphere Fermi limit Photon-to-Baryon Original Paczynski Goodman But, Hascoet+ 11 Zou+ 10, Aoi+ 10 Omodei Racusin Ghisellini BB Zhang

Baryon Loading  or r/r 0  =E/Mc 2  * ~10 3  * ~10 3 IS Synchro. Photosphere Fermi limit Photon-to-Baryon Original Paczynski Goodman Fine Tuning? Omodei Racusin Ghisellini BB Zhang

Internal Shock in RD? Time (t) Space (r) r0r0 Light path ⇒ No Internal Shock Rapid Shell Slow Shell

Confinement External pressure or Magnetic Tchekhovskoy Narayan

Internal Shock in RD? Time (t) Space (r) r0r0 Light path ⇒ No Internal Shock

Internal Shock in RD! Time (t) Space (r) r0r0 Light path

Internal Shock in RD! Time (t) Space (r) r0r0 Light path All rapid shells can catch-up like IS r/  2 always increases (so trivial) Poynting models

Internal Shock of RD Flow 1. Internal Shock is possible for RD outflow 2. Up to a large radius 3. Repeatedly ⇒ Can keep e ± up to high 

Cocoon Confinement Pressure balance at 1.Jet head 2.Cocoon-Star 3.Jet-Cocoon ~1/2 for n=3 (Rad. env.) ⇒ Dissipative Aloy+ 00, Lazzati+ 09, Morsony+ 10, Mizuta+ 10

Cocoon Confinement Pressure balance at 1.Jet head 2.Cocoon-Star 3.Jet-Cocoon ~1/2 for n=3 (Rad. env.) ⇒ Dissipative Aloy+ 00, Lazzati+ 09, Morsony+ 10, Mizuta+ 10

Fast Cocoon just escaping from the jet head sideways at the breakout  fc ~  j (t break )~10-30 p fc ~r -8/3 p j ~r -4 ⇒ Confine ⇒ persist around the jet ⇒ Internal Shock

Shock ⇒  acceleration ⇒ e ± Photons carries almost all the energy Shock via Compton (  mediated shock) Fermi-like acceleration of photons y-parameter can be of unity Appreciable energy can go to  →e ± Outflow can keep e ±  T ~  t’ shock /t’ dyn >1 electron/positron Density or  Blandford & Payne 78 Budnik+ 10

Turbulence T. Inoue, Asano & KI 11 A small  n is enough to drive turbulence Richtmyer-Meshkov turbulence 3D Rela. MHD Thompson 94

Lorentz Factor =2/3 in the last eq. If e ± are kept by internal shocks out to e ± photosphere High Lorentz Factor c.f. KI(10) for baryonic case

Extended  -Generation Photo- sphere Radiation-Dom. Internal Shock MeV GeV ~  rel 2 m e c 2 Shocks would continue beyond photosphere

CTA ~20GeV-100TeV x10 Sensitivity  ~1-2 min FOV~5-10 deg ~20 s slew (LST) ~2015 (?) ~150€ TeV  from GRB or not? O’Brien Granot S. Inoue

Summary  or r/r 0  =E/Mc 2  * ~10 3  * ~10 3 IS Synchro. Photosphere Fermi limit Photon-to-Baryon Original Paczynski Goodman Fine Tuning?

Summary Original Paczynski Goodman  or r/r 0  =E/Mc 2  * ~10 3  * ~10 3 IS Synchro. Photosphere Fermi limit Photon-to-Baryon UnexploredFrontier? RD Internal Shock via Confinement UnexploredFrontier?

Implications Lorentz factor: Cutoff probed by CTA Non-thermal spectrum ~ Band Extended  generation, deep inside  - sphere Early afterglow, High efficiency is possible GeV lag ~ r photosphere /c  fc 2 UHECR, neutrino Magnetic field dissipation Blandford-Znajek McKinney

T. Inoue, Asano & KI 11 f=1.8 B Amplification & Decay behind shock

Most Ancient Object A massive star’s death just 600 Myr after the Big Bang GRB z~8.2

First GRB Pop III (Zero Metal) ~ M  (!?) Pop III (Zero Metal) ~ M  (!?) Present Day Massive Star ~20M  Abel+ 02 Bromm+ 02 Omukai+ 03 Yoshida+ 08 Gigantic (x100) z~10-30??? Komissarov & Barkov 10 Meszaros & Rees 10

Massive Envelope Ohkubo+ 09 Heger+ 03 Suwa & KI 10 No mass loss via line driven wind R/c~10 3 s > T GRB ~10s ⇒ No GRB? Core Envelope

Envelope Accretion Suwa & KI 10 Energetic Very long Modest L Bright phase ⇒ Cocoon ⇒ v Jet head

Analytic Expressions

GRB jet can breakout the first star!