GRB 080916C AND GRB 090510: THE HIGH-ENERGY EMISSION AND THE AFTERGLOW

We constrain the physical composition of the outflows of GRBs 080916C and 090510 with the prompt emission data and find that the former is likely magnetic, while the latter may be baryonic. The X-ray and optical afterglow emission of both GRBs can be reasonably fitted using the standard external shock model but the density profiles of the circum-burst medium are different. We also propose a simple method to estimate the number of seed photons supposing the GeV afterglow photons are due to the inverse Compton radiation of external forward shock electrons. The seed photons needed in the modeling are too many to be realistic for both events. The synchrotron radiation of the forward shock seems able to account for the GeV afterglow data.

[1]  R. E. Hughes,et al.  A limit on the variation of the speed of light arising from quantum gravity effects , 2009, Nature.

[2]  A. J. van der Horst,et al.  SWIFT AND FERMI OBSERVATIONS OF THE EARLY AFTERGLOW OF THE SHORT GAMMA-RAY BURST 090510 , 2009, 0910.1629.

[3]  L. A. Antonelli,et al.  AGILE DETECTION OF DELAYED GAMMA-RAY EMISSION FROM THE SHORT GAMMA-RAY BURST GRB 090510 , 2009, 0908.1908.

[4]  Pawan Kumar,et al.  On the generation of high-energy photons detected by the Fermi Satellite from gamma-ray bursts , 2009, 0905.2417.

[5]  A. Pe’er,et al.  EVIDENCE OF AN INITIALLY MAGNETICALLY DOMINATED OUTFLOW IN GRB 080916C , 2009, 0904.2943.

[6]  Wei-Hong Gao.  Optical/infrared flares of GRB 080129 from late internal shocks , 2009, 0903.2768.

[7]  D. Wei,et al.  The initial Lorentz factors of fireballs inferred from the early X-ray data of SWIFT GRBs , 2009, 0902.2613.

[8]  S. B. Cenko,et al.  The redshift and afterglow of the extremely energetic gamma-ray burst GRB 080916C , 2009, 0902.0761.

[9]  T. Piran,et al.  The possible high-energy emission from GRB 080319B and origins of the GeV emission of GRBs 080514B, 080916C and 081024B , 2008, 0811.2997.

[10]  G. Sala,et al.  A STRONG OPTICAL FLARE BEFORE THE RISING AFTERGLOW OF GRB 080129 , 2008, 0811.4291.

[11]  T. Piran,et al.  High-energy γ-ray emission from gamma-ray bursts — before GLAST , 2008, 0805.2221.

[12]  Tsvi Piran,et al.  Gamma‐ray burst efficiency and possible physical processes shaping the early afterglow , 2006, astro-ph/0601054.

[13]  Bing Zhang,et al.  Gamma-Ray Bursts: Progress, Problems & Prospects , 2004 .

[14]  F. A. Harrison,et al.  A Study of the Afterglows of Four GRBs: Constraining the Explosion and Fireball Model , 2003, astro-ph/0307056.

[15]  Zhi-Yun Li,et al.  Wind Interaction Models for Gamma-Ray Burst Afterglows: The Case for Two Types of Progenitors , 1999, astro-ph/9908272.

[16]  T. Piran.  Gamma-ray bursts and the fireball model , 1998, astro-ph/9810256.

[17]  K. Cheng,et al.  The spectral flattening of the low-energy component in gamma-ray bursts , 1996 .

[18]  Cambridge,et al.  Cooling Timescales and Temporal Structure of Gamma-Ray Bursts , 1996, astro-ph/9605005.

[19]  B. Paczyński.  Super-Eddington winds from neutron stars , 1990 .