NICER, NuSTAR, and Insight-HXMT Views to the Newly Discovered Black Hole X-Ray Binary Swift J1727.8-1613

• Published in: Astrophysical journal. Letters Vol. 960; no. 2; p. L17
• Main Authors: Peng, Jing-Qiang, Zhang, Shu, Shui, Qing-Cang, Zhang, Shuang-Nan, Kong, Ling-Da, Chen, Yu-Peng, Wang, Peng-Ju, Ji, Long, Qu, Jin-Lu, Tao, Lian, Ge, Ming-Yu, Chang, Zhi, Li, Jian, Li, Zhao-sheng, Yu, Zhuo-Li, Yan, Zhe
• Format: Journal Article
• Language: English
• Published: Austin The American Astronomical Society 01.01.2024; IOP Publishing
• Subjects: Black holes; Corona; Spectral analysis; Spectrum analysis; X ray binaries; X ray stars; X-ray astronomy; X-ray binary stars; X-rays
• ISSN: 2041-8205; 2041-8213
• DOI: 10.3847/2041-8213/ad17ca

Swift J1727.8–1613 is a black hole X-ray binary newly discovered in 2023. We perform spectral analysis with simultaneous Insight-HXMT, NICER, and NuSTAR observations when the source was approaching the hard intermediate state. Such a joint view reveals an additional hard component apart from the normally observed hard component with reflection in the spectrum, to be distinguished from the usual black hole X-ray binary systems. By including this extra component in the spectrum, we have measured a high spin of 0.98 − 0.07 + 0.02 and an inclination of around 40 − 0.8 + 1.2 °, which is consistent with NICER results reported before. However, we find that the additional spectral component cannot be exclusively determined due to the model degeneracy. Accordingly, a possible jet/corona configuration is adjusted to account for the spectral fitting with different model trials. The extra component may originate either from a relativistic jet or a jet base/corona underneath a slow jet.