NuSTAR and Swift Observations of the Extragalactic Black Hole X-ray Binaries

Abstract

We present the results obtained from detailed spectral and timing studies of extra-galactic black hole X-ray binaries LMC~X--1 and LMC~X--3, using simultaneous observations with {\it Nuclear Spectroscopic Telescope Array (NuSTAR)} and {\it Neil Gehrels Swift} observatories. The combined spectra in the $0.5-30$~keV energy range, obtained between 2014 and 2019, are investigated for both sources. We do not find any noticeable variability in $0.5-30$~keV light curves, with $0.1-10$~Hz fractional rms estimated to be $<2$\%. No evidence of quasi-periodic oscillations is found in the power density spectra. The sources are found to be in the high soft state during the observations with disc temperature $T_{\mathrm{in}}\sim 1$~keV, photon index, $\Gamma >2.5$ and thermal emission fraction, $f_{\mathrm{disc}}>80$\%. An Fe K$\alpha$ emission line is detected in the spectra of LMC~X--1, though no such feature is observed in the spectra of LMC~X--3. From the spectral modelling, the spins of the black holes in LMC~X--1 and LMC~X--3 are estimated to be in the range of $0.92-0.95$ and $0.19-0.29$, respectively. The accretion efficiency is found to be, $\eta \sim 0.13$ and $\eta \sim 0.04$ for LMC~X--1 and LMC~X--3, respectively.

9 pages, 5 figures, accepted for publication in MNRAS. Comments are welcome

References in corpus (6)

• X-ray Properties of Black-Hole Binaries
• Modelling the behaviour of accretion flows in X-ray binaries
• A Determination of the Spin of the Black Hole Primary in LMC X-1
• Implications of Recent Measurements of the Milky Way Rotation for the Orbit of the Large Magellanic Cloud
• Accretion Flow Evolution of a New Black Hole Candidate MAXI J1348-630 During the 2019 Outburst
• Estimation of the black hole spin in LMC X-1 using AstroSat

Cited by in corpus (7)

• A Systematic View of Ten New Black Hole Spins
• Systematically Revisiting All NuSTAR Spins of Black Holes in X-Ray Binaries
• The spin measurement of MAXI J1348-630 using the Insight-HXMT data
• Accretion Properties and Estimation of Spin of Galactic Black Hole Candidate Swift J1728.9-3613 with NuSTAR during its 2019 outburst
• Broadband X-ray Spectroscopy and Estimation of Spin of the Galactic Black Hole Candidate GRS 1758-258
• Black hole spin estimation of XTE J2012+381 using simultaneous observations of Swift/XRT and NuSTAR
• Multi-mission view of extragalactic black hole X-ray binaries LMC X-1 and LMC X-3: evolution of broadband spectral features