Estimation of Spin and Mass of the Black Hole in MAXI J1348–630 from the Soft State Using NICER and NuSTAR Observations

ABSTRACT Black holes are characterized by their mass and spin. X-ray observations can be used to estimate these two quantities in black hole systems such as black hole X-ray binaries (BHXRB). Here we analysed near-simultaneous data of BHXRB MAXI J1348–630 from Neutron Star Interior Composition Explorer (NICER) (0.6–10.0 keV) and Nuclear Spectroscopic Telescope Array (NuSTAR) (3.0–79 keV) during the soft and hard states. Considering the distance of the source to be 2.2 kpc, the spin and mass of the black hole were estimated from the modeling of the soft state spectrum of the source. The spin and mass of the black hole were found to be $0.80_{-0.02}^{+0.02}$ and $8.7_{-0.3}^{+0.3}\, \mathrm{M}_\odot$, respectively. The inclination of the source was determined to be $36.5^{\circ}\, \pm \, 1.0^{\circ}$. Using these quantities in the hard state spectral model, the inner radius of the accretion disc was constrained for all three hard states of the source.