Spectral characteristics of the black hole binary 4U 1957+115: a multi mission perspective

Title

Spectral characteristics of the black hole binary 4U 1957+115: a multi mission perspective

Creator

Mudambi S.P.; Gudennavar S.B.; Misra R.; Bubbly S.G.

Description

We report spectral analysis of the persistent black hole X-ray binary, 4U 1957+115, using AstroSat, Swift, and NuSTAR observations carried out between 2016 and 2019. Modelling with a disc emission, thermal Comptonization, and blurred reflection components revealed that the source was in the high-soft state with the disc flux ?87 per cent of the total and high-energy photon index ?2.6. There is an evidence that either the inner disc radius varied by ?25 per cent or the colour hardening factor changed by ?12 per cent. The values of the inner disc radius imply that for a non-spinning black hole, the black hole mass is < 7 M ? and the source is located > 30 kpc away. On the other hand, a rapidly spinning black hole would be consistent with the more plausible black hole mass of < 10 M ? and a source distance of ?10 kpc. Fixing the distance to 10 kpc and using a relativistic accretion disc model, constrained the black hole mass to 6 M? and inclination angle to 72. A positive correlation is detected between the accretion rate and inner radii or equivalently between the accretion rate and colour factor. 2022 The Author(s).

Source

Monthly Notices of the Royal Astronomical Society, Vol-517, No. 3, pp. 4489-4496.

Date

2022-01-01

Publisher

Oxford University Press

Subject

accretion; accretion discs; black hole physics - X-rays: low mass X-ray binaries; X-rays: individual: 4U 1957+115

Coverage

Mudambi S.P., Department of Physics and Electronics, CHRIST (Deemed to be University), Bangalore Central Campus, Bengaluru, 560029, India; Gudennavar S.B., Department of Physics and Electronics, CHRIST (Deemed to be University), Bangalore Central Campus, Bengaluru, 560029, India; Misra R., Inter-University Centre for Astronomy and Astrophysics, Ganeshkhind, Pune, 411007, India; Bubbly S.G., Department of Physics and Electronics, CHRIST (Deemed to be University), Bangalore Central Campus, Bengaluru, 560029, India

Rights

All Open Access; Green Open Access

Relation

ISSN: 358711; CODEN: MNRAA

Format

Online

Language

English

Type

Article

Identifier

https://doi.org/10.1093/mnras/stac2952

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