Revisiting the galactic X-ray binary MAXI J1631-479: Implications for high inclination and a massive black hole

TL;DR

This study performs a detailed spectral analysis of the galactic X-ray binary MAXI J1631-479, revealing insights into the black hole's properties, accretion disk evolution, and system inclination through data from NICER and NuSTAR.

Contribution

It offers new constraints on the black hole's spin, mass, and disk inclination, and tracks accretion disk property changes during state transitions.

Findings

Black hole spin constrained with high precision.

Disk inclination angle determined from spectral modeling.

Black hole mass estimated using combined X-ray and optical data.

Abstract

X-ray spectroscopy of galactic black hole binaries serve as a powerful tool to gain an overall understanding of the system. Not only can the properties of the accretion disk be studied in detail, the fundamental properties of the black hole can also be inferred. The pursuit of these objectives also leads to an indirect validation of general relativity in strong field limit. In this work we carry out a comprehensive spectral analysis of the galactic X-ray binary MAXI J1631-479 using data from NICER and NuSTAR observatories. We trace the evolution of the accretion disk properties such as density, ionization, Fe abundance, etc as the source transitions from a disk dominated soft state to a power law dominated hard intermediate state. We provide strong constrains on the spin of the black hole and the inclination of the inner disk. We also use the soft state NICER observations to constrain the black hole mass using distance estimates from optical observations.