Characteristics of Two-episode Emission Patterns in Fermi Long Gamma-Ray Bursts

Two-episode emission components separated by quiescent gaps in the prompt emission of gamma-ray bursts (GRBs) have been observed in the Swift era, but there is a lack of spectral information due to the narrow energy band of the Swift/Burst Alert Telescope. In this paper, a systematic analysis of the...

Full description

Saved in:
Bibliographic Details
Published in:The Astrophysical journal 2018-08, Vol.862 (2), p.155
Main Authors: Lan, Lin, Lü, Hou-Jun, Zhong, Shu-Qing, Zhang, Hai-Ming, Rice, Jared, Cheng, Ji-Gui, Du, Shen-Shi, Li, Long, Lin, Jie, Lu, Rui-Jing, Liang, En-Wei
Format: Article
Language:English
Subjects:
Astrophysics
Emission analysis
Fluence
Gamma ray bursts
Gamma rays
gamma-ray burst: general
Light curve
methods: statistical
Power law
Spectra
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Two-episode emission components separated by quiescent gaps in the prompt emission of gamma-ray bursts (GRBs) have been observed in the Swift era, but there is a lack of spectral information due to the narrow energy band of the Swift/Burst Alert Telescope. In this paper, a systematic analysis of the spectral and temporal properties of the prompt emission of 101 Fermi/Gamma-ray Burst Monitor detected long GRBs show the existence of two-episode emission components in the light curves, with quiescent times of up to hundreds of seconds. We focus on investigating the differences of those two emission episodes. We find that the light curves of the two emission components exhibit different behavior, e.g., a soft emission component that either precedes or follows the main prompt emission or that the intensity of the two emission episodes are comparable with each other. No statistically significant correlation in the duration of the two emission episodes can be claimed. We define a new parameter as the ratio of the peak flux of the first and second emission episodes and find that a higher corresponds to a larger fluence. The preferred spectral model in our analysis is a cutoff power-law model for most GRBs. The distribution of Ep for episodes I and II range from tens of keV to 1000 keV with a lognormal fit and there are no significant differences between them. Moreover, we do not find significant relationships between and Ep for the two emission episodes. Those results suggest that these two-episode emission components likely share the same physical origin.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/aacda6