The spin measurement of the black hole SLX 1746-331 using Insight-HXMT observations

We present an X-ray spectral analysis of a black hole X-ray binary SLX 1746-331 during the 2023 outburst using five $\mathit{\text{Insight}}$-HXMT observations. We jointly use the reflection model $\mathtt{\text{relxillcp}}$ and the general relativistic thermal thin disk model $\mathtt{\text{kerrbb}}$ to fit the spectra from 2 - 100 keV. By jointly fitting the five spectra, we constrained the black hole mass to be $M=5.8\pm 0.3M_{\odot }$ and dimensionless spin parameter to be $a_{\ast }=0.88_{-0.02}^{+0.01}$ (90 percent statistical confidence). The reflection model shows that SLX 1746-331 is a high-inclination system with the inclination angle $i=63.7_{-1.0}^{+1.3}$ degrees, the accretion disk has a density $\mathrm{l}\mathrm{o}\mathrm{g}N\sim 16\mathrm{c}{\mathrm{m}}^{-3}$. In addition, with the different reflection model $\mathtt{\text{relxilllp}}$, which assumes a lamp-post geometry corona, we still give similar results.