In Pursuit of the Least Luminous Galaxies

TL;DR

This paper reviews the importance of ultra-faint dwarf galaxies as probes of dark matter and discusses the progress and future prospects of discovering these faint galaxies through wide-field surveys.

Contribution

It provides a comprehensive overview of the current state and future directions in the search for the faintest galaxies around the Milky Way.

Findings

Ultra-faint dwarf galaxies are key to understanding dark matter distribution.

Survey astronomy has significantly advanced the census of faint galaxies.

Future wide-field surveys will likely discover more ultra-faint dwarf galaxies.

Abstract

The dwarf galaxy companions to the Milky Way are unique cosmological laboratories. With luminosities as low as 10^-7 L_MW, they inhabit the lowest mass dark matter halos known to host stars and are presently the most direct tracers of the distribution, mass spectrum, and clustering scale of dark matter. Their resolved stellar populations also facilitate detailed studies of their history and mass content. To fully exploit this potential requires a well-defined census of virtually invisible galaxies to the faintest possible limits and to the largest possible distances. I review the past and present impacts of survey astronomy on the census of Milky Way dwarf galaxy companions, and discuss the future of finding ultra-faint dwarf galaxies around the Milky Way and beyond in wide-field survey data.