# Direct detection of supernova progenitor stars with ZTF and LSST

## TL;DR

This study investigates the potential of ground-based wide-field surveys like ZTF and LSST to directly detect supernova progenitor stars by combining multiple images, aiming to improve detection rates over traditional methods.

## Contribution

It introduces a novel approach of combining pre- and post-explosion images from ground-based surveys to identify supernova progenitors, and estimates detection rates for LSST.

## Key findings

- ZTF achieved limiting magnitudes of about 23 mag in g and r bands.
- No progenitors detected in ZTF data for 29 SNe within z<0.01.
- LSST is expected to detect about 50 red supergiant progenitors over ten years.

## Abstract

The direct detection of core-collapse supernova (SN) progenitor stars is a powerful way of probing the last stages of stellar evolution. However, detections in archival Hubble Space Telescope images are limited to about one per year. Here, we explore whether we can increase the detection rate by using data from ground-based wide-field surveys. Due to crowding and atmospheric blurring, progenitor stars can typically not be identified in pre-explosion images alone. Instead, we combine many pre-SN and late-time images to search for the disappearance of the progenitor star. As a proof of concept, we implement our search for ZTF data. For a few hundred images, we achieve limiting magnitudes of about 23 mag in the g and r band. However, no progenitor stars or long-lived outbursts are detected for 29 SNe within z<0.01, and the ZTF limits are typically several magnitudes less constraining than detected progenitors in the literature. Next, we estimate progenitor detection rates for the Legacy Survey of Space and Time (LSST) with the Vera C. Rubin telescope by simulating a population of nearby SNe. The background from bright host galaxies reduces the nominal LSST sensitivity by, on average, 0.4 mag. Over the ten-year survey, we expect the detection of about 50 red supergiant progenitors and several yellow and blue supergiants. The progenitors of SNe Ib and Ic are detectable if they are brighter than -4.7 mag or -4.0 mag in the LSST i band, respectively. In addition, we expect the detection of hundreds of pre-SN outbursts depending on their brightness and duration.