Abstract Details
| Name: Sachindra Naik Affiliation: Physical Research Laboratory Conference ID: ASI2025_506 Title : Properties of a low-mass active galactic nucleus UGC 6728 Authors and Co-Authors : Sachindra Naik (1), Prantik Nandi (1,2), Sandip K. Chakraborty (2), Narendra Layek (1), Neeraj Kumari (1,3) Abstract Type : Poster Abstract Category : Galaxies and Cosmology Abstract : We performed a comprehensive analysis of data from 15 years of X-ray observations of a low mass bare AGN, UGC 6728. Our study encompasses both spectral and temporal aspects of this source. The spectral properties of this source are studied using various phenomenological and physical models. From our study, we conclude that (a) the observed variability in X-ray luminosity is not attributed to the hydrogen column density N_H as UGC 6728 exhibits a bare nucleus, implying a negligible N_H contribution along the line of sight, and (b) the spectral slope in the X-ray band demonstrates a systematic variation over time, indicating a transition from a relatively hard state to a comparatively soft state. We propose that the underlying accretion dynamics around the central object account for this behavior. By performing X-ray spectral fitting, we estimate the mass of the central supermassive black hole in UGC 6728 to be 7.13 +/- 1.23 x 10^5 M_Sun. Based on our spectral and temporal analysis, we suggest that UGC 6728 lacks a prominent Compton hump or exhibits a very subtle hump that remains undetectable in our analysis. Furthermore, the high-energy X-ray photons in this source are likely to originate from the low-energy X-ray photons through inverse Compton scattering in a Compton cloud, highlighting a connection between the emission in two energy ranges. We noticed a strong soft excess component in the initial part of our observations, which later reduced substantially. This variation of soft excess is explained in view of accretion dynamics. |