Beacons In the Dark: Using Novae and Supernovae to Detect Dwarf Galaxies in the Local Universe

TL;DR

This paper suggests using luminous transients like novae and supernovae as tools to detect faint dwarf galaxies in the local universe, especially those too dim for direct observation in upcoming surveys.

Contribution

It introduces a novel method of detecting ultra-faint dwarf galaxies through their transient events, expanding the observational reach beyond traditional photometric limits.

Findings

Novae detectable up to 30 Mpc with LSST

Supernovae observable on Gpc scales

Transient rates could reveal numerous low-mass dwarf galaxies

Abstract

We propose that luminous transients, including novae and supernovae, can be used to detect the faintest galaxies in the universe. Beyond a few Mpc, dwarf galaxies with stellar masses $<10^6 M_{\odot}$ will likely be too faint and/or too low in surface brightness to be directly detected in upcoming large area ground-based photometric surveys. However, single epoch LSST photometry will be able to detect novae to distances of $\sim30$ Mpc and SNe to Gpc-scale distances. Depending on the form of the stellar mass-halo mass relation and the underlying star formation histories of low mass dwarfs, the expected nova rates will be a few to $\sim100$ yr$^{-1}$ and the expected SN rates (including both type Ia and core-collapse) will be $\sim10^2-10^4$ within the observable ($4\pi$ sr) volume. The transient rate associated with intrahalo stars will be comparably large, but these transients will be located close to bright galaxies, in contrast to the dwarfs, which should trace the underlying large scale structure of the cosmic web. Aggressive follow-up of hostless transients has the potential to uncover the predicted enormous population of low mass field dwarf galaxies.