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

Abstract

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 and XMM–Newton observations. Coherent pulsation of the source was detected at ∼40.578 ± 0.001 s using NuSTAR observation. We analysed pulse profiles of the source in different energy bands using NuSTAR and 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 anticorrelated with luminosity. In the 1-yr 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 $\sim 5.56 \times 10^{-11}\, {\rm erg}\, {\rm cm}^{-2}\, \mathrm{s}^{-1}$ and the corresponding luminosity is $\sim 1.66 \times 10^{37}\, {\rm erg}\, \mathrm{s}^{-1}$. 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.