Speaker
Description
In recent decades, distinct subtypes of Type Ia supernovae (SNe Ia) have been discovered that deviate from the canonical luminosity-width relationship. These non-standardizable objects risk contaminating high redshift (z > 0.5) cosmological samples, including those anticipated from the Roman Space Telescope and LSST. While SN Ia subtypes are traditionally determined using peak-light optical spectra, these upcoming surveys will be spectroscopically incomplete, posing a significant challenge to maintaining sample purity. Building on nearly twenty years of Swift observations of 130 SNe Ia in the local universe, we present a novel method for distinguishing SN Ia subtypes using only rest-frame UV photometry. Our method successfully removes all non-standardizable subtypes from our sample. Based on this legacy Swift data, we project that our diagnostic will yield ~90% pure samples of standardizable SNe Ia observed by LSST at redshift z > 0.5 and prove a valuable tool in ensuring the purity of modern cosmological samples of SNe Ia.
