Abstract Details

Name: Dhruba Saikia
Affiliation: Inter-University Centre for Astronomy and Astrophysics
Conference ID: ASI2020_646
Title : HI 21 cm absorption towards radio AGNs of different accretion modes
Authors and Co-Authors : Yogesh Chandola (PMO), D.J. Saikia (IUCAA), Di Li (NAOC)
Abstract Type : Poster
Abstract Category : Extragalactic Astronomy
Abstract : In this talk, we will present results of HI absorption experiment done using the Giant Metrewave Radio Telescope (GMRT) towards a sample of radio active galactic nuclei (AGN) classified as high excitation radio galaxies (HERGs) and low excitation radio galaxies (LERGs). HI absorption has been detected towards seven radio AGNs, six of which are new. Combined with other sources from literature classified as LERGs or HERGs, we confirm our earlier result that compact radio AGNs with WISE colour W2-W3 >2 have higher detection rates compared to those with W2-W3<2. We find that the HI absorption detection rate is higher for HERGs compared to LERGs which is mainly due to differences in WISE colours of host galaxies and radio source structures. For similar compact radio structures and WISE colours W2-W3 > 2, we don't find any difference in detection rates of two types of AGNs. We further analysed the kinematics towards these sources. We find that in comparison to the HERGs, LERGs show a wider range in the shift of centroid velocities relative to the optical systemic velocity, possibly due to differences in jet-interstellar medium interaction.