RHESSI Tests of Quasi-Thermal Gamma-Ray Burst Spectral Models
arXiv:0908.2433 · doi:10.1088/0004-637X/714/1/881
Abstract
Prompt gamma-ray burst spectra evolve on short time scales, suggesting that time-resolved spectral fits may help diagnose the still unknown prompt emission mechanism. We use broad-band gamma-ray data from the RHESSI spacecraft to test quasi-thermal models with high signal-to-noise time-resolved spectra of nine bright gamma-ray bursts. In contrast to results reported in more narrow energy bands, the quality of the fits of quasi-thermal models is poor in relation to fits of the phenomenological Band function. Moreover, the best-fit parameters for the simplest quasi-thermal model, a black body plus a nonthermal power law, show significant dependence on the fit band. Models that replace the power law with more complicated nonthermal functions are not robust for the data considered here and decrease the physical relevance of the fit black body.
14 pages, 17 figures; submitted to ApJ
References in corpus (12)
- Fermi Observations of GRB 090902B: A Distinct Spectral Component in the Prompt and Delayed Emission
- The Complete Spectral Catalog of Bright BATSE Gamma-Ray Bursts
- Identification and properties of the photospheric emission in GRB090902B
- Quasi-blackbody component and radiative efficiency of the prompt emission of gamma-ray bursts
- A new method of determining the initial size and Lorentz factor of gamma-ray burst fireballs using a thermal emission component
- Intrinsic properties of a complete sample of HETE-2 gamma-ray bursts. A measure of the GRB rate in the Local Universe
- Gamma-Ray Burst Spectral Correlations: Photospheric and Injection Effects
- Black-body components in Gamma-Ray Bursts spectra?
- Global characteristics of GRBs observed with INTEGRAL and the inferred large population of low-luminosity GRBs
- Observations of the intense and ultra-long burst GRB041219a with the Germanium Spectrometer on INTEGRAL
- Observation of an unexpected hardening in the spectrum of GRB 021206
- RHESSI Spectral Fits of Swift GRBs
Cited by in corpus (6)
- Detection of a Thermal Spectral Component in the Prompt Emission of GRB 100724B
- A Theory of Mulicolor Black Body Emission from Relativistically Expanding Plasmas
- Observational evidence of dissipative photospheres in gamma-ray bursts
- On the Connection of Gamma-Ray Bursts and X-Ray Flashes in the BATSE and RHESSI Databases
- Spectral components in the bright, long GRB 061007: properties of the photosphere and the nature of the outflow
- Study of shock wave dynamics produced by interaction of a fireball with the surrounding medium to it, to explain the x-ray afterglow of Gamma Ray Burst-GRBs