The Temporal and Spectral Characteristics of "Fast Rise and Exponential Decay" Gamma-Ray Burst Pulses

TL;DR

This study analyzes the temporal and spectral features of 52 FRED gamma-ray burst pulses, revealing correlations between pulse duration, spectral hardness, and asymmetry, providing constraints for GRB models.

Contribution

It offers a detailed analysis of FRED pulse characteristics, highlighting the need for multiple parameters to model GRB temporal and spectral behavior.

Findings

Long-duration pulses have harder spectra and are less luminous.

More asymmetric pulses have steeper peak energy evolution.

FRED pulses differ from long-lag pulses in temporal and spectral properties.

Abstract

In this paper we have analyzed the temporal and spectral behavior of 52 Fast Rise and Exponential Decay (FRED) pulses in 48 long-duration gamma-ray bursts (GRBs) observed by the CGRO/BATSE, using a pulse model with two shape parameters and the Band model with three shape parameters, respectively. It is found that these FRED pulses are distinguished both temporally and spectrally from those in long-lag pulses. Different from these long-lag pulses only one parameter pair indicates an evident correlation among the five parameters, which suggests that at least $\sim$4 parameters are needed to model burst temporal and spectral behavior. In addition, our studies reveal that these FRED pulses have correlated properties: (i) long-duration pulses have harder spectra and are less luminous than short-duration pulses; (ii) the more asymmetric the pulses are the steeper the evolutionary curves of the peak energy ($E_{p}$) in the $\nu f_{\nu}$ spectrum within pulse decay phase are. Our statistical results give some constrains on the current GRB models.