Investigating the timing and spectral signatures of Be/X-ray pulsar RX J0520.5−6932 during its 2024 outburst using NuSTAR

The Be X-ray binary pulsar RX J0520.5-\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$-$$\end{document}6932 in the Large Magellanic Cloud recently underwent an outburst after a gap of about 10 years. This paper presents the timing and spectral analysis of this transient system using the NuSTAR observation that was made near the peak of the outburst. Coherent pulsations were detected with a period of 8.029877(9) s (at MJD 60412.87) up to 50 keV. The pulse profile was single-peaked and asymmetric, with the presence of two local minima on the slowly rising edge up to about 18 keV. The hard X-ray pulse profiles were relatively smooth. The 3–50 keV FPMA–FPMB energy spectrum was well described by a thermally comptonized continuum with an electron temperature of ∼\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sim $$\end{document}5.3 keV and a photon index of ∼\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sim $$\end{document}1.36. A broad ∼\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sim $$\end{document}6.32 keV Fe emission line and a cyclotron resonant scattering feature (CRSF) with ∼\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sim $$\end{document}32.3 keV central energy, corresponding to a surface magnetic field strength of ∼\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sim $$\end{document}2.8×1012\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$2.8\times 10^{12}$$\end{document} G were also required to describe the energy spectrum. The pulse phase resolved spectroscopy indicated significant variation in energy and width of the CRSF and iron emission line. A ∼\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sim $$\end{document}14.6 keV absorption feature was also detected at specific pulse phases.