Tracing Black Hole Signatures in Several Black Hole Candidates Based on Their X-Ray Spectral Evolution
1 Astronomy Study Program, Faculty of Mathematics and Natural Sciences, Institut Teknologi, Bandung, Indonesia
2 Astronomy Research Division, Faculty of Mathematics and Natural Sciences, Institut Teknologi, Bandung, Indonesia
* Corresponding author: firstname.lastname@example.org
Published online: 21 August 2020
Investigation of spectral evolution of four black hole candidates was carried out by using color-color diagram as well as spectral fitting on Swift/XRT data. Newly found candidates, which are classified as low-mass X-ray binary system based on their transient nature, are the focus of our work. We compare their spectral evolutions to that of XTE J1752-223, a transient system and a more convincing black hole candidate whose mass has been determined from spectral-timing correlation scaling. In addition, comparison to Cygnus X-1, a well-known stellar-mass black hole, was done despite its persistent nature. The spectral fitting, by using a combination of thermal disk and non-thermal component model, results in the innermost temperature values in the range of the typical innermost temperature of black hole binary which is 0.7 – 1.5 keV. The spectral evolutions of the candidates bear a resemblance to both Cygnus X-1 and XTE J1752-223. We note that during Swift/XRT observations, the spectra of Cygnus X-1 and IGR J17451-3022 are mostly dominated by the non- thermal component. We conclude that the compact object of MAXI J1535- 571 and MAXI J1828-249 is highly likely to be a black hole. However, the lack of data rendered conclusive result impossible for IGR J17454-2919.
Key words: Keywords: / black hole binary / black hole candidates / black hole signatures / low-mass X-ray binary / spectral evolution
© The Authors, published by EDP Sciences, 2020
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