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Prompt high-energy emission from gamma-ray bursts in the internal shock model
| Content Provider | Semantic Scholar |
|---|---|
| Author | Bošnjak, Željka Daigne, Frédéric Dubus, Guillaume |
| Copyright Year | 2009 |
| Abstract | Context. Gamma-ray bursts (GRB) are powerful, short duration events with a spectral luminosity peaking in the keV MeV (BATSE) range . The prompt emission is thought to arise from electron s accelerated in internal shocks propagating within a highl y relativistic outflow. Aims. The launch ofFermioffers the prospect of observations with unprecedented sensit ivity in high-energy (HE,>100 MeV) gammarays. The aim is to explore the predictions for HE emission fr m internal shocks, taking into account both dynamical and r adiative aspects, and to deduce how HE observations constrain the pro p rties of the relativistic outflow. Methods. The prompt GRB emission is modelled by combining a time-depe ndent radiative code, solving for the electron and photon distributions, with a dynamical code giving the evolution o f the physical conditions in the shocked regions of the outflo w. Synthetic lightcurves and spectra are generated and compared to obser vations. Results. The HE emission deviates significantly from analytical esti mates, which tend to overpredict the IC component, when the t ime dependence and full cross-sections are included. The explo ration of the parameter space favors the case where the domin ant process in the BATSE range is synchrotron emission. The HE component b comes stronger for weaker magnetic fields. The HE lightcur ve can display a prolonged pulse duration due to IC emission, or eve n a delayed peak compared to the BATSE range. Alternatively, having dominant IC emission in the BATSE range requires most electr ons to be accelerated into a steep power-law distribution an d implies strong second order IC scattering. In this case, the BATSE an d HE lightcurves are very similar. Conclusions. The combined dynamical and radiative approach allows a firm a ppraisal of GRB HE prompt emission. A diagnostic procedure is presented to identify from observations the do minant emission process and derive constrains on the bulk Lo rentz factor, particle density and magnetic field of the outflow. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://arxiv.org/pdf/0811.2956v2.pdf |
| Alternate Webpage(s) | http://arxiv.org/pdf/0811.2956v1.pdf |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Dynamical system Electron Eve Interferon Type II Kiloelectronvolt Magnetic Fields Photons Population Parameter Pulse duration Recombinant Interferon-gamma Sensit Shock Synchrotrons Synthetic intelligence diagnostic procedure |
| Content Type | Text |
| Resource Type | Article |
