September 11
An X-ray View of High-Redshift AGN: Obscuration, Metallicity, and Little Red Dots
Speaker: Yash Gursahani, UMD ASTR
Abstract: JWST has opened a window into the z > 10 Universe, a previously unexplored epoch when galaxies--and presumably supermassive black holes--were in an early stage of their growth. The violent collisions and mergers of nascent galaxies could mean that SMBH growth happened in an environment enshrouded by high column densities of gas. However, this material may have significantly sub-solar metal abundances at such early times, reducing the opacity to X-rays. In this talk, I will describe results from the Monte Carlo radiative transfer simulations I performed to answer how the X-ray emission from near these accreting SMBHs is reprocessed by an optically-thick, low-metallicity torus. I will also discuss the observational prospects of these systems with current and next-generation X-ray observatories. Lastly, I will touch on an application of low metallicity (i.e. dust-poor gas) to the mysterious Little Red Dots, in which the reduced coupling of radiation to dust could allow dense gas to stall near the SMBH, explaining their observed X-ray weakness.
Host: Jillian Rastinejad & Robert Stein