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arXiv · 2212.01003

Broadband mHz QPOs and spectral study of LMC X$-$4 with AstroSat

Rahul Sharma·Chetana Jain·Ketan Rikame·Biswajit Paul
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Abstract

We report the results of broadband timing and spectral analysis of data from an AstroSat observation of the High Mass X-ray binary LMC X$-$4. The Large Area X-ray Proportional Counter (LAXPC) and Soft X-ray Telescope (SXT) instruments on-board the AstroSat observed the source in August 2016. A complete X-ray eclipse was detected with the LAXPC. The 3$-$40 keV power density spectrum showed the presence of coherent pulsations along with a $\sim 26$ mHz quasi-periodic oscillation feature. The spectral properties of LMC X$-$4 were derived from a joint analysis of the SXT and LAXPC spectral data. The 0.5$-$25 keV persistent spectrum comprised of an absorbed high energy cutoff power law with photon index of $Γ\sim$ 0.8 and cutoff at $\sim$16 keV, a soft thermal component with kT$_{BB} \sim$ 0.14 keV and Gaussian components corresponding to Fe K$_α$, Ne \textsc{ix} and Ne \textsc{x} emission lines. Assuming a source distance of 50 kpc, we determined 0.5--25 keV luminosity to be $\sim 2 \times 10^{38}$ erg s$^{-1}$.

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Rahul Sharma, Chetana Jain, Ketan Rikame, Biswajit Paul. 2022-12-02. Broadband mHz QPOs and spectral study of LMC X$-$4 with AstroSat. https://doi.org/10.1093/mnras%2Fstac3572

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