Broadband Study of the Be/X-ray Binary Pulsar Erassu J012422.9-724248 in the Magellanic Bridge, Near the Eastern Wing of the Small Magellanic Cloud

The first four all-sky surveys with eROSITA the soft X-ray instrument on board the Spektrum-Roentgen-Gamma (SRG) satellite revealed a new X-ray source, eRASSU J012422.9-724248, in the Magellanic Bridge, near the Eastern Wing of the Small Magellanic Cloud (SMC). We performed a broad-band timing and spectral analysis using the optical and X-ray data of eRASSU J012422.9-724248. Using the X-ray observations with eROSITA, Swift, NuSTAR and optical data from the optical Gravitational Lensing Experiment (OGLE) and the Las Cumbres Observatory (LCO), we confirm the nature of eRASSU J012422.9-724248as a Be/X-ray binary (BeXRB) pulsar in the Magellanic Bridge. The position is coincident with that of an early-type star (OGLE ID SMC732.10.7). We detect the spin period at 341.71 s in NuSTAR data and infer a period of 63.65 d from the 15 yr monitoring with OGLE, that we interpret as the orbital period of the system. A tentative CRSF at 12.3 keV is identified in NuSTAR spectra with 1.8 sigma. The source appears to show a persistent X-ray luminosity and an optical magnitude transition on the long timescale. We propose eRASSU J012422.9-724248is a new member of the class of persistent BeXRBs.