Neutral Hydrogen Observations of Low Surface Brightness Galaxies around M101 and NGC 5485

TL;DR

This study uses HI observations to investigate gas content in low surface brightness dwarf galaxy candidates around M101, revealing gas-poor status in most and suggesting environmental effects like stripping influence satellite properties.

Contribution

First wide-band HI follow-up of LSB dwarf candidates around M101, providing insights into their gas content and environmental interactions.

Findings

5 out of 27 candidates detected in HI

Most non-detections are likely associated with NGC 5485 group

Gas richness of satellites aligns with Milky Way and similar hosts

Abstract

We present atomic hydrogen (HI) observations using the Robert C. Byrd Green Bank Telescope along the lines-of-sight to 27 low surface brightness (LSB) dwarf galaxy candidates discovered in optical searches around M101. We detect HI reservoirs in 5 targets and place stringent upper limits on the remaining 22, implying that they are gas poor. The distances to our HI detections range from 7 Mpc --150 Mpc, demonstrating the utility of wide-bandpass HI observations as a follow-up tool. The systemic velocities of 3 detections are consistent with that of the NGC~5485 group behind M101, and we suggest that our 15 non-detections with lower distance limits from the optical are associated with and have been stripped by that group. We find that the gas richnesses of confirmed M101 satellites are broadly consistent with those of the Milky Way satellites, as well as with those of satellites around other hosts of comparable mass, when survey completeness is taken into account. This suggests that satellite quenching and gas stripping proceeds similarly around halos of similar mass, in line with theoretical expectations.