A Comprehensive Study of Bright Fermi-GBM Short Gamma-Ray Bursts: I. Multi-Pulse Lightcurves and Multi-Component Spectra

TL;DR

This study analyzes the brightest short Gamma-ray Bursts detected by Fermi-GBM, revealing multi-pulse lightcurves and multi-component spectra, with correlations suggesting a common physical origin for spectral features.

Contribution

It provides a comprehensive analysis of bright SGRBs, modeling their lightcurves with multiple pulses and fitting their spectra with combined models, highlighting correlations between spectral parameters.

Findings

Lightcurves are well fitted by 1 to 3 FRED pulses.

Spectral energy distributions are well reproduced by CPL + BB models.

Peak energy of CPL correlates with BB temperature, indicating a possible shared origin.

Abstract

Sorted by the photon fluences of short Gamma-ray Bursts (SGRBs) detected by the Fermi- Gamma Ray Burst Monitor (GBM), nine brightest bursts are selected to perform a comprehensive analysis. All GRB lightcurves are fitted well by 1 to 3 pulses that are modelled by fast-rising exponential decay profile (FRED), within which the resultant rising time is strongly positive-correlated with the full time width at half maxima (FWHM). A photon spectral model involving a cutoff power-law function and a standard blackbody function (CPL + BB) could reproduce the spectral energy distributions of these SGRBs well in the bursting phase. The CPL's peak energy is found strongly positive-correlated with the BB's temperature, which indicates they might be from the same physical origin. Possible physical origins are discussed to account for these correlations.