GBT26B-360

A GBT Survey of the M33's Molecular Gas in OH

Abstract

We a proposing to observe the CO-bright molecular gas in M33 with the GBT covering a pointed survey of 14 GBT beams spaced by the beamwidth in the 18cm OH lines. OH has been shown to be a promising tracer of the so-called 'CO-dark' gas, and faint thermal OH emission has been observed by the GBT in M31, revealing a large amount of molecular gas missed by CO observations alone (Busch 2024). We have extended our studies to M31's bright molecular ring, which is in preparation for publication. Initial results showcase large amounts of detectable OH when CO is also present. These regions should be covered first in a systematic way. We now propose to extend our sensitive OH survey towards M33, which, with its much lower metallicity, should have ample amounts of dark gas. In combination with M31, and M33 survey in OH will begin to coalesce a picture of the CO-dark gas inventory in two very different galactic ecosystems. We picture this survey of the CO-bearing gas to be a first survey of M33, where in future semesters we will cover the rest of the HI disk in the outskirts.

Investigators

Name	Institution
Michael Busch *	National Radio Astronomy Observatory
Cosima Eibensteiner	National Radio Astronomy Observatory; Bonn, Universität

* indicates the PI