Extremely Dense Gas around Little Red Dots and High-redshift AGNs
The James Webb Space Telescope (JWST) observations have revolutionized extragalactic research, particularly with the discovery of low-luminosity active galactic nuclei (AGNs) at high redshifts, powered by accreting black holes (BHs) with masses of 10^6-8 Msun. One remarkable distinction of these JWST-identified AGNs, compared to their low-redshift counterparts, is that at least ~20% of them present H \alpha and/or H \beta absorption, which must be associated with extremely dense gas along the line of sight. In this talk, I'll review these observation results and give physical insights into the thermal and dynamical properties of inflow/outflow gas in these highz AGN. I will also briefly mention a relationship between these absorption features and other characteristics of JWST-identified AGNs, such as X-ray weakness.
