Resolved Dwarf Galaxy Searches within ∼5 Mpc with the Vera Rubin Observatory and Subaru Hyper Suprime-Cam*

We present a preview of the faint dwarf galaxy discoveries that will be possible with the Vera C. Rubin Observatory and Subaru Hyper Suprime-Cam in the next decade. In this work, we combine deep ground-based images from the Panoramic Imaging Survey of Centaurus and Sculptor and extensive image simulations to investigate the recovery of faint, resolved dwarf galaxies in the Local Volume with a matched-filter technique. We adopt three fiducial distances (1.5, 3.5, and 5 Mpc) and quantitatively evaluate the effects on dwarf detection of varied stellar backgrounds, ellipticity, and Milky Way foreground contamination and extinction. We show that our matched-filter method is powerful for identifying both compact and extended systems, and near-future surveys will be able to probe at least similar to 4.5 mag below the tip of the red giant branch (TRGB) for a distance of up to 1.5 Mpc and similar to 2 mag below the TRGB at 5 Mpc. This will push the discovery frontier for resolved dwarf galaxies to fainter magnitudes, lower surface brightnesses, and larger distances. Our simulations show the secure census of dwarf galaxies down to M ( V ) approximate to -5, -7, and -8 will soon be within reach, out to 1.5, 3.5, and 5 Mpc, respectively, allowing us to quantify the statistical fluctuations in satellite abundances around hosts and parse environmental effects as a function of host properties.

Automated summary

This study presents a preview of the potential faint dwarf galaxy discoveries that could be made with the Vera C. Rubin Observatory and Subaru Hyper Suprime-Cam in the next decade. By utilizing a matched-filter technique, the researchers were able to quantitatively evaluate the effects of various factors on dwarf detection and predict the future ability to detect faint dwarf galaxies at greater distances. The simulations indicate that a secure census of dwarf galaxies down to certain magnitudes will soon be achievable, allowing for a deeper understanding of satellite abundances and environmental effects in relation to host properties.