Gamma Ray Bursts in the Fermi era: the spectral energy distribution of the prompt emission

Abstract

Gamma Ray Bursts (GRBs) show evidence of different light curves, duration, afterglows, host galaxies and they explode within a wide redshift range. However, their spectral energy distributions (SEDs) appear to be very similar showing a curved shape. Band et al. (1993) proposed a phenomenological description of the integrated spectral shape for the GRB prompt emission, the so called Band function. In this letter we suggest an alternative scenario to explain the curved shape of GRB SEDs: the log-parabolic model. In comparison with the Band spectral shape our model is statistically favored because it fits the GRB spectra with one parameter less than the Band function and it is motivated by a theoretical acceleration scenario. The new Fermi observations of GRBs will be crucial to disentangle between these two models.

4pages, 4 figures, 1 table, ApJ letter accepted

References in corpus (6)

• Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology
• Fermi Observations of GRB 090902B: A Distinct Spectral Component in the Prompt and Delayed Emission
• X-ray spectral evolution of TeV BL Lac objects: eleven years of observations with BeppoSAX, XMM-Newton and SWIFT satellites
• Signatures of synchrotron emission and of electron acceleration in the X-ray spectra of Mrk 421
• Prospects for GRB Science with the Fermi Large Area Telescope
• SSC radiation in BL Lac sources, the end of the tether

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• The Bright and the Slow -- GRBs 100724B \& 160509A with high-energy cutoffs at $\lesssim 100$MeV
• X-ray and TeV emissions from High Frequency Peaked BL Lacs
• Broadband study of GRB 091127: a sub-energetic burst at higher redshift?
• X-ray spectral curvature of High Frequency Peaked BL Lacs: a predictor for the TeV flux
• LOFAR observations of 4C+19.44. On the discovery of low frequency spectral curvature in relativistic jet knots
• A new fitting function for GRB MeV spectra based on the internal shock synchrotron model
• Spectral evolution of long Gamma Ray Burst prompt emission: electrostatic acceleration and adiabatic expansion