Burst phase distribution of SGR J1935+2154 based on Insight-HXMT

TL;DR

This study analyzes the burst phase distribution of SGR J1935+2154 during its 2020 outburst using Insight-HXMT and Fermi-GBM data, revealing uniform burst start times but spectrum-dependent photon phase distributions.

Contribution

It provides the first detailed phase distribution analysis of bursts from SGR J1935+2154 during an active outburst, highlighting spectral dependence in photon phase characteristics.

Findings

Burst start times are uniformly distributed within the spin phase.

Photon phase distribution depends on the burst's energy spectrum.

Different spectral types show distinct phase distribution patterns during activity.

Abstract

On April 27, 2020, the soft gamma ray repeater SGR J1935+2154 entered its intense outburst episode again. Insight-HXMT carried out about one month observation of the source. A total number of 75 bursts were detected during this activity episode by Insight-HXMT, and persistent emission data were also accumulated. We report on the spin period search result and the phase distribution of burst start times and burst photon arrival times of the Insight-HXMT high energy detectors and Fermi Gamma-ray Burst Monitor (GBM). We find that the distribution of burst start times is uniform within its spin phase for both Insight-HXMT and Fermi-GBM observations, whereas the phase distribution of burst photons is related to the type of a burst's energy spectrum. The bursts with the same spectrum have different distribution characteristics in the initial and decay episodes for the activity of magnetar SGR J1935+2154.