SRGA J124404.1-632232/SRGU J124403.8-632231: a new X-ray pulsar discovered in the all-sky survey by SRG

TL;DR

This paper reports the discovery and confirmation of a new Galactic X-ray pulsar with a Be-star companion, identified through all-sky SRG surveys and follow-up observations, marking one of the first such discoveries by SRG.

Contribution

It presents the first identification of a Galactic X-ray pulsar by SRG, including detailed follow-up observations confirming its properties.

Findings

Discovered a new X-ray pulsar with a ~538 s spin period.

Confirmed Be-star as the optical counterpart.

First Galactic X-ray pulsar identified by SRG.

Abstract

Ongoing all-sky surveys by the the eROSITA and the Mikhail Pavlinsky ART-XC telescopes on-board the Spectrum Roentgen Gamma (SRG) mission have already revealed over a million of X-ray sources. One of them, SRGA J124404.1-632232/SRGU J124403.8-632231, was detected as a new source in the third (of the planned eight) consecutive X-ray surveys by ART-XC. Based on the properties of the identified optical counterpart it was classified as a candidate X-ray binary (XRB). We report on the follow-up observations of this source with Nuclear Spectroscopic Telescope Array (NuSTAR), Neil Gehrels Swift Observatory (Swift), and the Southern African Large Telescope (SALT), which allowed us to unambiguously confirm the initial identification and establish SRGU J124403.8-632231 as a new X-ray pulsar with a spin period of ~538 s and a Be-star companion, making it one of the first Galactic X-ray pulsars discovered by SRG.