From X-ray Binaries to Ultraluminous X-ray Sources: Evolution of Accretion Disks Across Different States with Relativistic and Non-Relativistic Disk Models

Abstract

M82 X-1 has been under the spotlight as a possible host for an intermediate-mass black hole (IMBH). Previous spectral studies pointed towards much lower black hole mass values but obtaining better constraints on the black hole mass was subject to limitations due to the complexity of the parameter space and the nature of the disk model adopted.

To efficiently overcome any effects of local minima or complex degeneracies of individual parameters of the model, we employ the Bayesian X-ray Analysis (BXA) software to perform a global exploration of the parameter space and obtain a comprehensive view of the important parameters using combined simultaneous Chandra + NuSTAR spectra of M82 X-1. Employing relativistic accretion disk models that include the signatures of the physical properties of the black hole on the observed spectrum indicates that it's difficult to reproduce the observed spectral shape assuming an IMBH with a mass around 1000-10000 M☉ and disk temperatures as high as 6 keV, as previously reported.

Our results suggest, instead, that the data collected so far on M82 X-1 favor an interpretation involving a stellar-mass black hole accreting in an extreme regime. In this contribution, I will provide a brief overview of our findings of the first global parameter exploration of M82 X-1 and discuss the general implications of relativistic vs. non-relativistic treatments of the accretion disk in similar binary systems.