Active Galactic Nuclei (AGNs) are extreme object in the universe. AGNs are supermassive black holes that located at the centre of the galaxies. AGNs are powered by the accretion process. I study the accretion flow properties around AGNs to understand the extreme physics at the vicinity of the black holes.

Changing-States AGNs (CSAGNs) are a subset of AGNs that show extreme variability. The CSAGNs are known to switch between type-1 and type-2 in the timescale of months to years. Unification model which is used to explain the AGNs over 40 years, cannot explain the CSAGNs. The change in accretion rate believed to be the origin of the CSAGNs, although, it is highly debated. Currenly, I am involve in the study of the CSAGNs to uncover its secret.

About 70% AGNs in the local universe are obscured. They are often found to hidden behind giant gas clouds. These giant clouds also acts as the accretion reservoir of the AGNs. I study the obscuring properties of the AGNs to understand its connection with the AGNs evolution.

Black Hole X-ray Binaries (BHXBs) are the scaled-down version of AGNs. Thus, the timescale for BHXBs are small, compared to the AGNs. Hence, the BHXBs provide an excellent opportunity to study the accretion dynamics in details. I study the BHXBs to understand the accretion physics around black holes.

Compton cloud or corona is region close to the black holes that emits powerful radiation in the hard X-ray bands. Till date, the size, or geometry is unknown to us. The X-ray polarimetry can solve this long-standing mystery. With the X-ray polarimetric study, I try to solve this problem.

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