NICER observations of the black hole candidate MAXI J0637-430 during the 2019-2020 outburst

Altamirano, Diego (2021) NICER observations of the black hole candidate MAXI J0637-430 during the 2019-2020 outburst. Monthly Notices of the Royal Astronomical Society, 504 (4), 4793-4805. (doi:10.1093/mnras/stab1231).

Record type: Article

Abstract

We present detailed timing and spectral studies of the black hole candidate MAXI J0637-430 during its 2019-2020 outburst using observations with the Neutron Star Interior Composition Explorer (NICER) and the Neil Gehrels Swift Observatory. We find that the source evolves through the soft-intermediate, high-soft, hard-intermediate, and low-hard states during the outburst. No evidence of quasi-periodic oscillations is found in the power-density spectra of the source. Weak variability with fractional rms amplitude ${\lt}5{{\ \rm per\ cent}}$ is found in the softer spectral states. In the hard-intermediate and hard states, high variability with the fractional rms amplitude of ${\gt}20{{\ \rm per\ cent}}$ is observed. The 0.7-10 keV spectra with NICER are studied with a combined disc-black-body and nthcomp model along with the interstellar absorption. The temperature of the disc is estimated to be 0.6 keV in the rising phase and decreased slowly to 0.1 keV in the declining phase. The disc component was not detectable or absent during the low-hard state. From the state-transition luminosity and the inner edge of the accretion flow, we estimate the mass of the black hole to be in the range of 5-12 M⊙, assuming the source distance of d < 10 kpc.

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NICER observations of the black hole candidate MAXI J0637-430 during the 2019-2020 outburst - Accepted Manuscript

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e-pub ahead of print date: 3 April 2021

Published date: 1 July 2021

Additional Information: Funding Information: This research has made use of data and/or software provided by the High Energy Astrophysics Science Archive Research Center (HEASARC), which is a service of the Astrophysics Science Division at NASA/GSFC and the High Energy Astrophysics Division of the Smithsonian Astrophysical Observatory. This work has made use of XRT data supplied by the UK Swift Science Data Centre at the University of Leicester, UK. Work at Physical Research Laboratory, Ahmedabad, is funded by the Department of Space, Government of India Publisher Copyright: © 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.

Keywords: Accretion, Accretion discs, Stars: individual: (MAXI J0637-430), X-Rays:binaries