Spectral and timing analysis of BeXRB eRASSU J050810.4-660653 recently discovered in the Large Magellanic Cloud (LMC)

TL;DR

This study presents detailed timing and spectral analysis of the Be/X-ray binary pulsar eRASSU J050810.4-660653 in the LMC, revealing its pulsation, spectral behavior, and accretion regime through NuSTAR and XMM-Newton data.

Contribution

It provides the first detailed timing and spectral characterization of this recently discovered BeXRB in the LMC, including pulse profile evolution and phase-resolved spectroscopy.

Findings

Detected pulsation at ~40.578 s.

Pulse profile suggests a pencil-beam pattern.

Spectral parameters vary with pulse phase.

Abstract

We have studied the Be/X-ray binary (BeXRB) pulsar eRASSU J050810.4-660653 recently discovered in the Large Magellanic Cloud (LMC). Timing and spectral features of the source have been discussed in detail using NuSTAR \& XMM-Newton observations. Coherent pulsation of the source was detected at $\sim 40.578\;\pm\;0.001$ s using NuSTAR observation. We analyzed pulse profiles of the source in different energy bands using NuSTAR \& XMM-Newton data. The pulse-profile evolved with time but was generally suggestive of a pencil-beam dominated pattern, which combined with the measured luminosity, indicates that the source may be accreting in the sub-critical regime. The pulse fraction follows a linearly increasing trend with photon energy and is anti-correlated with luminosity. In the 1 year interval between the XMM and NuSTAR observations the pulse period shortened by 0.021 s which could be consistent with spin-up or orbital Doppler effect. The average flux of the source in (3-50) keV energy range is found to be $\sim 5.56\;\times\;10^{-11}\;erg\;cm^{-2}\;s^{-1}$ and the corresponding luminosity is $\sim 1.66\;\times\;10^{37}\;erg\;s^{-1}$. The variation of spectral parameters with pulse phase is studied using phase resolved spectroscopy which reveals that the observed photon index becomes harder with increasing flux.