A Comprehensive Analysis of Insight-HXMT Gamma-Ray Burst Data. I. Power Density Spectrum

• DOI: 10.3847/1538-4357/ad5f90
• Publication Date: 2024-09-09T06:32:12Z
• Authors: Zi-Min Zhou; Xiang-Gao Wang; En-Wei Liang; Jia-Xin Cao; Hui-Ya Liu; Cheng-Kui Li; Bing Li; Da-Bin Lin; Tian-Ci Zheng; Rui-Jing Lu; Shao-Lin Xiong; Ling-Jun Wang; Li-Ming Song; Shuang-Nan Zhang
• Keywords: QB460-466; High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology; High Energy Physics - Phenomenology (hep-ph); FOS: Physical sciences; Gamma-ray bursts; Astrophysics; Astrophysics - High Energy Astrophysical Phenomena

Abstract The power density spectrum (PDS) is a powerful tool to study light curves of gamma-ray bursts (GRBs). We show the average PDS and individual PDS analysis with GRB data from the Hard X-ray Modulation Telescope (also named Insight-HXMT). The values of the power-law index of the average PDS (

α

P

¯

) for long GRBs (LGRBs) vary from 1.58 to 1.29 (for 100–245, 245–600, and 600–2000 keV). The Insight-HXMT data allow us to extend the energy of the LGRBs up to 2000 keV, and a relation between

α

P

¯

and energy E is obtained:

α

P

¯

∝

E

− 0.09

(8–2000 keV). We first systematically investigate the average PDS and individual PDSs for short GRBs (SGRBs), and obtain

α

P

¯

∝

E

− 0.07

(8–1000 keV), where the values of

α

P

¯

vary from 1.86 to 1.34. The distribution of the power-law index of an individual PDS (α) of an SGRB is consistent with that of an LGRB, and the α value for the group with a dominant timescale (the bent power law) is higher than that for the group with no dominant timescale (the single power law). Both LGRBs and SGRBs show similar α and

α

P

¯

, which indicates that they may be the result of similar stochastic processes. Typical values of the dominant timescale τ for LGRBs and SGRBs are 1.58 s and 0.02 s, respectively. It seems that τ varies in proportion to the duration of GRBs T 90, with a relation

τ ∝

T

90

0.86

. The GRB light curve may result from superposing a number of pulses with different timescales. No periodic or quasi-periodic signal above the 3σ significance threshold is found in our sample.