FIRST RESULTS FROM THE MADCASH SURVEY: A FAINT DWARF GALAXY COMPANION TO THE LOW-MASS SPIRAL GALAXY NGC 2403 AT 3.2 MPC

We report the discovery of the faintest known dwarf galaxy satellite of a Large Magellanic Cloud (LMC) stellar-mass host beyond the Local Group (LG), based on deep imaging with Subaru/Hyper Suprime-Cam. Magellanic Analog Dwarf Companions And Stellar Halos (MADCASH). J074238+652501-dw lies similar to 35 kpc in projection from NGC 2403, a dwarf spiral galaxy at D approximate to 3.2 Mpc. This new dwarf has Mg = -7.4 +/- 0.4 and a half- light radius of 168 +/- 70. pc, at the calculated distance of 3.39 +/- 0.41 Mpc. The color-magnitude diagram reveals no evidence of young stellar populations, suggesting that MADCASH. J074238+652501-dw is an old, metal-poor dwarf similar to low-luminosity dwarfs in the LG. The lack of either detected HI gas (M-HI/L-V < 0.69M circle dot/L circle dot,based on Green Bank Telescope observations) or GALEX NUV/FUV flux enhancement is consistent with a lack of young stars. This is the first result from the MADCASH survey, which is conducting a census of the stellar substructure and faint satellites in the halos of Local Volume LMC analogs via resolved stellar populations. Models predict a total of similar to 4-10 satellites at least as massive as MADCASH. J074238+652501-dw around a host with the mass of NGC 2403, with 2-3 within our field of view, slightly more than the one such satellite observed in our footprint.