Friday, March 14, 2025 at 12:15 pm

JILA Foothills Room

Megan Newsome, UC Santa Barbara

"Supermassive Black Hole Environments: Causes or Effects of Tidal Disruption Events?"

Abstract:

Tidal disruption events (the disruption of a star after passing too close to a supermassive black hole) show a unique preference for occurring post-starburst (PSB) host galaxies. These galaxies are very rare and show a distinct lack of current, ongoing star formation, while still showing stellar populations indicative of "recent" star formation that ceased abruptly, up to ~1.5Gyr ago. How the small-scale dynamics of a galaxy's nucleus are connected to the large-scale dynamics of the galaxy’s total star formation history remains to be discerned. To unveil the cause of the enhanced TDE rates in post- starburst galaxies, we present a resolved spatial characterization of the stellar population, as a function of distance from the galactic nucleus, for the PSB host of the TDE ASASSN-14li using Hubble Space Telescope (HST) spectroscopy. Our analysis probes the smallest spatial resolution of a PSB host to date, and we find evidence for a stellar population age gradient and stratified gas within <50 pc of the central SMBH, potentially indicating gas inflows from a minor merger. Together, these findings demonstrate how the unique environments of post-starburst galaxies create conditions conducive to enhanced TDE rates.

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