SGR 0755$-$2933: a new High Mass X-ray binary with the wrong name

TL;DR

This study reclassifies SGR 0755-2933 from a soft gamma-ray repeater to a high mass X-ray binary based on follow-up X-ray observations, highlighting the importance of accurate counterpart identification for understanding burst origins.

Contribution

The paper provides the first detailed follow-up analysis that reclassifies SGR 0755-2933, challenging its previous identification as a magnetar and proposing a new classification.

Findings

The source is a high mass X-ray binary, not a soft gamma-ray repeater.

The true soft X-ray counterpart to the burst remains unidentified.

Magnetar origin of the burst is uncertain and needs further investigation.

Abstract

The soft gamma-ray repeater candidate SGR 0755$-$2933 was discovered in 2016 by Swift/BAT, which detected a short ($\sim$30 ms) powerful burst typical of magnetars. To understand the nature of the source, we present here an analysis of follow-up observations of the tentative soft X-ray counterpart of the source obtained with Swift/XRT, NuSTAR and Chandra. From our analysis we conclude that, based on the observed counterpart position and properties, it is actually not a soft gamma ray repeater but rather a new high mass X-ray binary. We suggest to refer to it as 2SXPS J075542.5$-$293353. We conclude, therefore, that the available data do not allow us to confirm existence and identify the true soft X-ray counterpart to the burst event. Presence of a soft counterpart is, however, essential to unambiguously associate the burst with a magnetar flare, and thus we conclude that magnetar origin of the burst and precise burst location remain uncertain and require further investigation.