Evolution of X-Ray Properties of MAXI J1535-571: Analysis with the TCAF Solution

TL;DR

This paper analyzes the spectral and timing evolution of the X-ray transient MAXI J1535-571 during its outburst using the TCAF model, providing insights into accretion flow dynamics and estimating the black hole's mass.

Contribution

It applies the TCAF model to multi-instrument data to study accretion flow evolution and estimate the black hole mass in MAXI J1535-571, which is a novel approach for this source.

Findings

Maximum flux reached 5 Crab in 2-10 keV band.

Black hole mass estimated between 7.9 and 9.9 solar masses.

Spectral state transitions correlated with accretion flow parameters.

Abstract

We present spectral and timing properties of the newly discovered X-ray transient source, MAXI J1535-571, which is believed to be a Galactic X-ray binary containing a black hole candidate (BHC) as the primary object. After its discovery on 2017 Sep. 2, it has been monitored regularly in multi-wavelength bands by several satellites. We use archival data of Swift (XRT and BAT) and MAXI (GSC) satellite instruments to study accretion flow dynamics of the source during the outburst. During its outburst, the source became very bright in the sky with a maximum observed flux of $5$~Crab in the $2-10$~keV GSC band. Similar to other transient BHCs, it also shows signatures of low frequency quasi-periodic oscillations (QPOs) during the outburst. Spectral data of different instruments are fitted with the transonic flow solution based two-component advective flow (TCAF) model fits file to find the direct accretion flow parameters. Evolution of spectral states and their transitions are understood from the model fitted physical flow parameters and nature of QPOs. We also estimate probable mass of the black hole from our spectral analysis as $7.9-9.9~M_\odot$ or $8.9\pm1.0~M_\odot$.