Light curve evolution and recalculation of black hole mass in the black hole X-ray binary SLX 1746-331

SLX 1746-331 is a black hole X-ray binary transient. Based on data from China’s Insight Hard X-ray Modulation Telescope (HXMT) satellite during its 2023 outburst, this paper conducts spectral and flux analysis of the luminosity decline phase of the outburst. The following results were obtained throughout the observation: (1) the light curve, hardness ratio, and spectral fitting parameters exhibit a two-stage evolution; (2) the disk flux and the inner disk temperature follow the Fdisk， 0.1−100 keV∝Tin4.25 relation; (3) the two stages of the light curve can be well fitted by exponential functions with different parameters, and the relationship between the parameters of the two exponential functions is β=2.04±0.06. These findings indicate that SLX 1746-331 underwent a transition from the very high state to the high soft state during its luminosity decline. Assuming a peak luminosity of 0.3LEdd during the high soft state, the black hole mass of SLX 1746-331 is estimated to be MBH=(3.11±1.75)M⊙. These results contribute to the estimation of black hole masses and the study of radiative properties in black hole X-ray binaries.