Studying the Properties of MAXI J1535-571 using Swift, MAXI and AstroSat data

Galactic X-ray transient black hole candidate MAXI J1535-571 was discovered on 2017 September 2 simultaneously by MAXI/GSC and Swift/BAT instruments. We use archival data of Swift (XRT and BAT), MAXI (GSC) and AstroSat (LAXPC) satellite instruments to make a detailed study on the accretion flow dynamics of the source during the initial period of the outburst. The daily average fluxes of MAXI/GSC and Swift/BAT and their ratio as HR (BAT/GSC fluxes) are used to understand the nature of source during the entire 2017-18 outburst. Low frequency quasi-periodic oscillations (QPOs) are observed during our detailed spectral and temporal analysis period of the outburst. Spectral analysis is done using two types of models: with phenomenological power-law or disk blackbody plus power-law model and with physical two component advective flow (TCAF) model. Studying the spectral and temporal properties of MAXI J1535-571, we categorized the spectral states during the outburst. The state transitions are also explained in a more physical point of views. The dynamic variation of QPOs and spectra are studied using AstroSat/LAXPC data. We have also estimated the mass of the black hole from the spectral fitted results.