2023/09/08 by M. McNanna, K. Bechtol, McNanna, M. +129 · 1 voice · 3 citations
#astro-ph.GA
paper · pdf · doi:10.48550/arxiv.2309.04467
We report results from a systematic wide-area search for faint dwarf galaxies at heliocentric distances from 0.3 to 2 Mpc using the full six years of data from the Dark Energy Survey (DES). Unlike previous searches over the DES data, this search specifically targeted a field population of faint galaxies located beyond the Milky Way virial radius. We derive our detection efficiency for faint, resolved dwarf galaxies in the Local Volume with a set of synthetic galaxies and expect our search to be complete to MV ~ (-7, -10) mag for galaxies at D = (0.3, 2.0) Mpc respectively. We find no new field dwarfs in the DES footprint, but we report the discovery of one high-significance candidate dwarf galaxy at a distance of 2.2\substack+0.05 -0.12 Mpc, a potential satellite of the Local Volume galaxy NGC 55, separated by 47 arcmin (physical separation as small as 30 kpc). We estimate this dwarf galaxy to have an absolute V-band magnitude of -8.0\substack+0.5 -0.3 mag and an azimuthally averaged physical half-light radius of 2.2\substack+0.5 -0.4 kpc, making this one of the lowest surface brightness galaxies ever found with μ= 32.3 mag \rm arcsec-2. This is the largest, most diffuse galaxy known at this luminosity, suggesting possible tidal interactions with its host.