Search for Diffuse Neutral Hydrogen and HI Clouds in the NGC 2403 Group
Katie M. Chynoweth, Glen I. Langston, Kelly Holley-Bockelmann, Felix, J. Lockman

TL;DR
This study used the Green Bank Telescope to search for faint neutral hydrogen clouds in the NGC 2403 group, finding likely Milky Way high velocity clouds instead of group-associated clouds, and setting upper limits on their mass and abundance.
Contribution
First sensitive search for diffuse HI clouds in the NGC 2403 group, providing constraints on their presence and properties compared to cosmological model predictions.
Findings
Detected 3 new HI clouds likely part of the Milky Way HVC population.
No HI clouds were found that match the predictions for the NGC 2403 group.
HI content of dark matter halos around NGC 2403 is less than 1% of their total mass.
Abstract
We have observed the NGC 2403 group of galaxies using the Robert C. Byrd Green Bank Telescope (GBT) in a search for faint, extended neutral hydrogen clouds similar to the clouds found around the M81/M82 group, which is located approximately 250 kpc from the NGC 2403 group along the same filament of galaxies. For an HI cloud with a size < 10 kpc within 50 kpc of a group galaxy, our 7-sigma mass detection limit is 2.2 x 10^6 M_sun for a cloud with a linewidth of 20 km/s, over the velocity range from -890 to 1750 km/s. At this sensitivity level we detect 3 new HI clouds in the direction of the group, as well as the known galaxies. The mean velocity of the new clouds differs from that of the group galaxies by more than 250 km/s, but are in the range of Milky Way High Velocity Clouds (HVCs) in that direction. It is most likely that the clouds are part of the Milky Way HVC population. If HI…
Peer Reviews
No public reviews on file for this paper yet. If you reviewed it on a platform where reviews are public (OpenReview, ICLR, NeurIPS, ICML), you can paste yours below so the community can read it here.
Videos
No videos yet. Explain this paper in a talk, walkthrough, or lecture? Add one.
