Type: Talk
Session: Transient and Variable Star Science II
Author: K-Ryan Hinds

Abstract: In the era of large, multi-band surveys, the ability to model photometric behaviour across multiple bands is a critical component to curating statistically complete samples for demographic analyses. We present detailed light curve analysis and parameter measurements for over 8000 supernovae (SNe) from the ZTF Bright Transient Survey using forced photometry and multi-band Gaussian process regression. Particular attention is paid to the rise time distribution of 663 Type II SNe, which is thought to be strongly dependent on the progenitor radius and the presence of CSM in the immediate vicinity of the progenitor stars. Using is empirically measured parameters and completeness of the magnitude limited Bright Transient Survey, we provide volume corrected distributions for CSM mass and radial extent in addition to radii and iron core masses for Type II SN progenitors. Our results suggest that a majority of Type II SN progenitors have pre-explosion CSM masses above 0.1 Msol and have mass-loss rates >0.01 Msol/yr. This has implications for the end-of-life mass-loss rates of RSGs and for late-stage stellar evolution generally. Assuming a standard wind velocity, we estimate the mass should be lost within a few decades years leading up to the explosion, requiring the mass-loss method to be substantial and effective.