Using Supernovae to Detect the Faintest Galaxies

Low-mass dwarf galaxies with stellar masses totalling less than a million times the Sun’s mass are expected to exist in huge numbers. However, these dwarf galaxies are very difficult to detect due to their low luminosities and low surface brightness. Only several of these dwarf galaxies have been found so far. They appear as ultra-diffuse extended sources and detecting them requires imaging large areas of the sky. With the exception of the nearest ones, these dwarf galaxies will remain beyond detection limits even with upcoming wide-field ground-based survey telescopes such as the Large Synoptic Survey Telescope (LSST).

Surface brightness of known dwarf galaxies in the Local Group from data compiled by McConnachie (2012). The dotted line marks the surface brightness limit that can be detected by LSST. Conroy & Bullock (2015).

Galaxies contain stars, and stars are the progenitors of nova and supernova explosions. A study by Conroy & Bullock (2015) investigates the use of nova and supernova explosions to detect the faintest dwarf galaxies in the universe. The detection of such a luminous transient with no apparent host galaxy could indicate the presence of a faint dwarf galaxy. LSST will be able to detect nova explosions out to ~100 million light years and supernova explosions out to billions of light years.

References:
- Conroy & Bullock (2015), “Beacons In the Dark: Using Novae and Supernovae to Detect Dwarf Galaxies in the Local Universe”, arXiv:1504.04015 [astro-ph.GA]
- McConnachie (2012), “The Observed Properties of Dwarf Galaxies in and around the Local Group”, AJ, 144, 4