Speaker
Description
There is now an amalgam of observational evidence that massive stars undergo enhanced and/or eruptive mass-loss in their final years before explosion. In this talk, I will present multi-wavelength observations of >40 type II SNe whose very early-time ("flash") spectra showed transient, narrow emission lines from shock interaction with confined circumstellar material (CSM) around their red supergiant (RSG) progenitor stars prior to shock breakout. I will discuss the observational properties of this "flash spectroscopy" SN sample, the largest to date, and how Swift-UVOT provided both crucial early-time coverage at UV wavelengths as well as direct evidence that UV emission is an essential metric for understanding CSM-interaction. This sample also includes the CSM-interacting type II SNe 2023ixf and 2024ggi, the closest and brightest SNe of the decade, for which I will present direct evidence of shock breakout emission as detected by Swift-UVOT. Lastly, I will discuss how robust modeling of such events with non-LTE radiative transfer codes is bolstered by early-time Swift-UVOT light curves and how such modeling allows for direct constraints on the mass-loss histories of the RSGs in their final years. Lastly, I will highlight on-going efforts for automatic Swift triggering on infant SNe discovered by the Zwicky Transient Facility and future prospects for probing the UV parameter space of young, CSM-interacting SNe.
