Clues from the prompt emission of GRB 080319B

Abstract

The extremely bright optical flash that accompanied GRB 080319B suggested, at first glance, that the prompt $\gamma$-rays in this burst were produced by Synchrotron self Compton (SSC). We analyze here the observed optical and $\gamma$ spectrum. We find that the very strong optical emission poses, due to self absorption, very strong constraints on the emission processes and put the origin of the optical emission at a very large radius, almost inconsistent with internal shock. Alternatively it requires a very large random Lorentz factor for the electrons. We find that SSC could not have produced the prompt $\gamma$-rays. We also show that the optical emission and the $\gamma$ rays could not have been produced by synchrotron emission from two populations of electron within the same emitting region. Thus we must conclude that the optical and the $\gamma$-rays were produced in different physical regions. A possible interpretation of the observations is that the $\gamma$-rays arose from internal shocks but the optical flash resulted from external shock emission. This would have been consistent with the few seconds delay observed between the optical and $\gamma$-rays signals.

References in corpus (4)

• A general scheme for modeling gamma-ray burst prompt emission
• High energy gamma-ray emission from Gamma-Ray Bursts -- before GLAST
• Continuous optical monitoring during the prompt emission of GRB 060111B
• Prompt optical emission from residual collisions in GRB outflows

Cited by in corpus (6)

• The Physics of Gamma-Ray Bursts and Relativistic Jets
• The Internal-Collision-Induced Magnetic Reconnection and Turbulence (ICMART) Model of Gamma-Ray Bursts
• Expected high energy emission from GRB 080319B and origins of the GeV emission of GRBs 080514B, 080916C and 081024B
• Inverse Compton cooling in Klein-Nishina regime and GRB prompt spectrum
• Photospheric Prompt Emission From Long Gamma Ray Burst Simulations -- I. Optical Emission
• Gamma-Ray Burst prompt emission from the synchrotron radiation of relativistic electrons in a rapidly decaying magnetic field