FLASH Talks **Note different time**: Jonathan Cohn (Texas A&M University) & Samuel Lai (Australian National University)


Friday, 09 September 2022 noon — 1 p.m. MST

NOIRLab Headquarters | 950 North Cherry Ave., Tucson, AZ 85719

FLASH Talks
Jonathan Cohn (Texas A&M University) & Samuel Lai (Australian National University)
Jonathan Cohn, Texas A&M University
ALMA gas-dynamical mass measurements of supermassive black holes in red nugget relic galaxies
Supermassive black holes (BHs) have been observed to correlate with host galaxy bulge properties, leading to a fundamental open question in galaxy evolution: do BHs and galaxies grow in lockstep, or does the growth of one precede that of the other? We have uncovered a sample of local compact galaxies with uniformly old (≥10 Gyr) stellar populations and small radii (effective radii of 0.7-3.1 kpc) for their stellar masses [(0.5-3.8)x10^11 solar masses]. These galaxies are thought to be local analogs/relics of z~2 quiescent galaxies. Previous stellar-dynamical modeling of three galaxies in this sample found BHs that were over-massive compared to the BH mass - bulge luminosity relation, indicating BHs may build the majority of their mass before their host galaxies. Here, we present 0.14"-0.22" resolution Atacama Large Millimeter/submillimeter Array (ALMA) CO(2-1) data of the rotating circumnuclear disks in three other local compact galaxies. We fit gas-dynamical models directly to the ALMA data cubes, assuming the CO emission originates from a dynamically cold, thin disk, and we use the dynamic nested sampling code dynesty to determine Bayesian posteriors. Finally, we place these galaxies on the BH - host galaxy relationships. Making more dynamical BH mass measurements for the sample of local compact galaxies will significantly advance our understanding of BH - host galaxy co-evolution.
 
Samuel Lai, Australian National University
Characterising High-redshift Black Holes and their Environments

 

Luminous Active Galactic Nuclei provide a unique opportunity to study black hole (BH) growth and host galaxy co-evolution in the high-redshift universe. Utilising the multiwavelength spectroscopic coverage of X-shooter and data from 100+ quasars between 3.5 < z < 7.5, we will present measurements of broad spectral features associated with ionised gas in close proximity to the BH accretion disk and discuss what can be gleaned about properties of the BH and its environment. We will also discuss the viability of a new method for constraining BH masses independent of reverberation mapping, using ray-traced models of multi-temperature accretion disk emission around rotating BHs.