Astronomy Colloquium

For years, we have been eagerly anticipating the promising capabilities that the JWST would bring to bear on scientific questions across all fields of astrophysics -- from exoplanets, to Milky Way structure, to cosmology. How is the reality of using data from JWST shaping up to meet expectations? In this talk I will discuss how the major technical leaps of JWST -- its spatial resolution, its sensitivity and its wavelength coverage -- are impacting astrophysics, specifically extragalactic astronomy and cosmology. My group is using JWST to unveil the evolution of supermassive black holes in centers of galaxies across cosmic time. I will present results from these programs, where JWST is revealing the complex physics of the interaction between the supermassive black holes and their host galaxies in unprecedented detail -- including the direct detection of the shockwaves driven into the interstellar medium by quasar winds and the discovery of close-separation dual quasars at cosmic noon. Throughout the talk, I will present and discuss other extragalactic astronomy highlights from the first two years of JWST data.

Jesse Greenstein was there at the dawn of AGN, starting with a paper with Maartin Schmidt in 1964, the year I was born.  The normal stochastic variability of AGN was discovered almost immediately, and it now can be studied statistically with parameters that correlate with properties of the black hole such as mass.  Gravitational micro-lensing of lensed quasars and modern reverberation mapping campaigns can be used to explore the structure of accretion disks and the origin of this variability in detail. But modern synoptic surveys have also revealed an expanding zoo of other types of AGN variability.  There are tidal disruption events (TDEs), changing look quasars (and blazars!) and "anomalous nuclear transients".  We will tour this landscape, what we have learned and what happens next.

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