Back to Business: SLX 1746–331 after 13 Years of Silence

• Published in: The Astrophysical journal Vol. 955; no. 2; pp. 96 - 105
• Main Authors: Peng, Jing-Qiang, Zhang, Shu, Wang, Peng-Ju, Zhang, Shuang-Nan, Kong, Ling-Da, Chen, Yu-Peng, Shui, Qing-Cang, Ji, Long, Qu, Jin-Lu, Tao, Lian, Ge, Ming-Yu, Ma, Rui-Can, Chang, Zhi, Li, Jian, Li, Zhao-sheng, Yu, Zhuo-Li, Yan, Zhe, Zhang, Peng, Xiao, Yun-Xiang, Zhao, Shu-Jie
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 01.10.2023; IOP Publishing
• Subjects: Astrophysics; Black holes; Circular orbits; Fluctuations; Inclination angle; Orbital stability; Outbursts; Silence; Spectral analysis; Spectrum analysis; Temperature dependence; X-ray binary stars
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/acf461

The black hole candidate system SLX 1746–331 was back to business in 2023, after a long silence of roughly 13 years. An outburst was observed thoroughly by Insight-HXMT and NICER. The outburst is characterized by spectral dominance of the soft state, where the joint Insight-HXMT and NICER spectral analysis shows the temperature dependence of the disk flux follows T in 3.98 , and thus suggests that the inner disk reaches its innermost stable circular orbit during almost the entire outburst. By assuming 0.3 L Edd for the peak flux and an inclination angle of zero degrees, the lower limit of the compact object hosted in this system is estimated as 3.28 ± 2.14 M ⊙ . We also look into the relation between the disk temperature and disk flux for a sample of black hole systems, and by taking the disk temperature derived in the outburst of SLX 1746–331, such a relation results in a mass estimation of 5.2 ± 4.5 M ⊙ . Finally, the spin of the compact object is constrained to be larger than 0.8 with the spectral model KERRBB.