Abstract Details
| Name: Rahul Musale Affiliation: Savitribai Phule Pune University Conference ID: ASI2025_687 Title : Neutral hydrogen gas and the unification scheme in compact radio AGNs Authors and Co-Authors : Rahul B. Musale 1, Rushikesh N. Bhutkar 1, Yogesh Chandola 2, D. J. Saikia 3 Abstract Type : Poster Abstract Category : Galaxies and Cosmology Abstract : In the orientation-based unification scheme, the dusty torus surrounding the central active galactic nucleus (AGN) obscures a direct view of the nucleus when the line of sight intersects it. In a sample of 85 compact steep- and peaked-spectrum radio AGNs (projected linear sizes < 20 kpc), we examined the unification scheme using the fraction of core radio emission as a statistical parameter for the orientation and HI 21-cm absorption properties to probe the neutral atomic hydrogen residing either in the torus or the interstellar medium. We find that the sources classified as Quasars have high core fractions, low HI detection rates, and column densities compared to those classified as high-excitation radio galaxies (HERGs). For HERGs the detection rate and HI column density increase with the increasing core fraction. We also find that sources classified as low-excitation radio galaxies (LERGs) have the highest core fraction, but HI absorption detection rates and column densities are higher than Quasars. We discuss these results in the context of the unification scheme. The compact sources are believed to reside in dense, inhomogeneous, and potentially asymmetric gaseous environments. Asymmetries could arise due to both the orientation effect and the inhomogeneous gas environment. We looked into asymmetry by estimating symmetry parameters such as lobe separation ratio, flux density ratio of lobes, and misalignment angle. We find no significant dependence of HI properties on symmetry parameters. |