Estimating the Black Hole Spin for the X-Ray Binary MAXI J1820+070
Abstract
MAXI J1820+070 is a newly discovered black hole X-ray binary, whose dynamical parameters, namely the black hole mass, the inclination angle, and the source distance, have recently been estimated. Insight-HXMT have observed its entire outburst from 2018 March 14. In this work, we attempted to estimate the spin parameter a*, using the continuum-fitting method and applying a fully relativistic thin disk model to the soft-state spectra obtained by Insight-HXMT. It is well known that a* is strongly dependent on three dynamical parameters in this method, and we have examined two sets of parameters. Adopting our preferred parameters: M = ${8.48}_{-0.72}^{+0.79}\,{M}_{\odot }$, i = 63° ± 3°, and D = 2.96 ± 0.33 kpc, we found a slowly spinning black hole of a* = 0.14 ± 0.09 (1σ), which gives a prograde spin parameter as the majority of other systems show. It is also possible for the black hole to have a retrograde spin (less than 0) if different dynamical parameters are taken.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- August 2021
- DOI:
- 10.3847/1538-4357/ac07a9
- arXiv:
- arXiv:2012.05544
- Bibcode:
- 2021ApJ...916..108Z
- Keywords:
-
- Black hole physics;
- X-ray binary stars;
- 159;
- 1811;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- doi:10.3847/1538-4357/ac07a9