First results from the MADCASH Survey: A Faint Dwarf Galaxy Companion to the Low Mass Spiral Galaxy NGC 2403 at 3.2 Mpc

Understand

We report the discovery of the faintest known dwarf galaxy satellite of an LMC stellar-mass host beyond the Local Group, based on deep imaging with Subaru/Hyper Suprime-Cam.

• MADCASH J074238+652501-dw lies $\sim$35 kpc in projection from NGC 2403, a dwarf spiral galaxy at $D$$\approx$3.2 Mpc.
• This new dwarf has $M_{g} = -7.4\pm0.4$ and a half-light radius of $168\pm70$ pc, at the calculated distance of $3.39\pm0.41$ 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 Local Group.