Where are All the Gas-Bearing Local Dwarf Galaxies? Quantifying Possible Impacts of Reionization

Understand

We present an approach for comparing the detections and non-detections of Local Group (LG) dwarf galaxies in large HI surveys to the predictions of a suite of n-body simulations of the LG.

• This approach depends primarily on a set of empirical scaling relations to connect the simulations to the observations, rather than making strong theoretical assumptions.
• We then apply this methodology to the Galactic Arecibo L-band Feed Array HI Compact Cloud Catalog (GALFA-HI CCC), and compare it to the ELVIS suite of simulations.
• This approach reveals a strong tension between the na\"ive results of the model and the observations: while there are no LG dwarfs in the GALFA-HI CCC, the simulations predict $\sim 10$.