Multi-Instrument Search for Gamma-Ray Counterpart of X-ray Transients detected by EP/WXT

TL;DR

This study systematically searches for gamma-ray counterparts to 63 X-ray transients detected by EP/WXT, finding 22% have gamma-ray counterparts and providing more stringent upper limits for others, enhancing understanding of their origins.

Contribution

The paper introduces a comprehensive pipeline, ETJASMIN, for detecting gamma-ray counterparts to X-ray transients, and presents the first systematic analysis of such associations.

Findings

22% of X-ray transients have gamma-ray counterparts.

ETJASMIN provides more stringent upper limits than individual instruments.

Analysis explores the relationship between X-ray transients and gamma-ray emissions.

Abstract

As a soft X-ray imager with unprecedentedly large field of view, EP/WXT has detected many (fast) X-ray transients, whose nature is very intriguing. Whether there is gamma-ray counterpart for the X-ray transient provides important implications for its origin. Some of them have been reported to be associated with GRB, however, a systematic study on the gamma-ray emission of these X-ray transients is lacking. In this work, we implemented a comprehensive targeted search for gamma-ray counterparts to 63 X-ray transients reported by EP/WXT during its first year of operation, using the dedicated multiple-instrument search pipeline, ETJASMIN, with GECAM-B, GECAM-C, Fermi/GBM, and \textit{Insight}-HXMT data. We find that 14 out of 63 (22\%) EP/WXT X-ray transients have gamma-ray counterparts. For other transients, ETJASMIN pipeline provided upper limit of gamma-ray emission, which is more stringent than that given by individual instrument. Moreover, we investigated the properties of the X-ray transients and their gamma-ray counterparts, and explored the relation between the x-ray transient and gamma-ray counterpart.