The Structure of Halo Gas around M33
Science with the new extragalactic radio surveys
Olivia Keenan
Cardiff University
Understanding the distribution of gas in and around galaxies is vital for our interpretation of galaxy formation and evolution. As part of the Arecibo Galaxy Environment Survey (AGES) we have observed the neutral hydrogen (HI) gas in and around the nearby Local Group galaxy M33 to a greater depth than the ALFALFA observations of Grossi et al. (2008). As part of this project we investigated the absence of optically detected dwarf galaxies in its neighbourhood, which is contrary to predictions of galaxy formation models. We observed 22 discrete clouds, 11 of which were previously undetected and none of which have optically detected counterparts. We find one particularly interesting hydrogen cloud, which has many similar characteristics to hydrogen distributed in the disk of a galaxy. This cloud, if it is at the distance of M33, has a HI mass of around 107 solar masses and a diameter of 18 kpc, making it larger in size than M33 itself. Additionally, we find many over-densities in the HI disk of M33, which may point towards that galaxy’s interaction history with M31.


13:30 - 15:00
EX - LT1 (100)