The 2021 Outburst of GX 339-4: Disc Evolution, QPO Trends, and Radiative Components responsible for QPOs

I will discuss the evolution of outburst in terms of spectral and temporal parameters of BHXB GX 339-4 during its 2021 outburst using LAXPC and SXT data onboard AstroSat. Our spectral studies suggest that disc is receding away from the compact object with increasing accretion rate duirng AstroSat's observation, while energy spectrum becomes harder with time. Our findings from temporal analysis suggest the presence of QPO in the power density spectrum (PDS), but they decrease with the evolution of outburst from ~5.4 Hz to ~4.7 Hz. After some time, we could not observe the QPOs in the PDS. At the end, I will discuss the possible radiative component responsible for the variation (QPO) found in the PDS using a generic model discussed by Garg et al. 2020.