Joint Observation of SGR J1935+2154 with \textit{Insight}-HXMT and KM40m during the active episode of October 2022

TL;DR

This study reports simultaneous X-ray and radio observations of magnetar SGR J1935+2154 during its active episode in October 2022, revealing 60 X-ray bursts and one associated radio burst, providing new insights into magnetar burst mechanisms.

Contribution

First simultaneous multi-wavelength observation of SGR J1935+2154 during an active episode, identifying a unique X-ray/radio association event with distinct properties.

Findings

Detected 60 X-ray bursts with Insight-HXMT during the active episode.

Found an X-ray burst on October 21 associated with a radio burst, differing from previous events.

Systematic analysis shows the associated X-ray burst has different properties from non-associated bursts.

Abstract

SGR J1935+2154 is the unique magnetar so far from which fast radio bursts have been detected. In October 2022, it resumed its burst activity, and we implemented a dedicated target-of-opportunity (ToO) observation on it from Oct. 13th to Nov. 1st, 2022 (about 940 ks in total) with \textit{Insight}-HXMT, while the KM40m radio telescope observed this source for about 1400 hours since Oct. 15th. We searched the LE, ME, and HE data of \textit{Insight}-HXMT in the overlapping observation time windows with the KM40m radio telescope and revealed 60 magnetar X-ray bursts (MXBs), while KM40m only detected 1 radio burst. In particular, we find that there is an X-ray burst on October 21 (denoted as MXB 221021) temporally associated with this radio burst. Interestingly, this association event shows very different morphology from those X-ray and radio association events from this source reported before (e.g., MXB/FRB 200428). Moreover, we systematically analyzed the temporal and spectral properties of the sample of MXBs during this observation and found that % the (radio-associated) MXB 221021 shows some different properties from other MXBs without associated radio bursts. These findings shed new light on the physical mechanisms of X-ray bursts and radio burst emission in magnetars.