Hot Gas Halos Around Nearby Late-Type Galaxies
Abstract
The hot phase (T > 10^6 K) of the circumgalactic medium contains an important fraction of all the baryons that will accrete onto massive galaxies or have been ejected from these galaxies through feedback, and it therefore encodes critical information for understanding galaxy formation. After decades of effort, we are now detecting the hot CGM observationally, and in this dissertation talk I present a number of novel observations of this gas, with particular emphasis on isolated late-type galaxies. I describe the first detections of hot halo emission out to 50 kpc around late-type galaxies, for the giant spirals NGC 1961 and UGC 12591. We find 5×10^9 M_{⊙} of hot gas in the CGM within this radius. I also present new results showing detections of hot CGM emission out to 50 kpc around L* galaxies, obtained by stacking images from the ROSAT All-Sky Survey. Finally, I discuss some of the implications of these detections for our understanding of the baryon budget of galaxies and the role of feedback in galaxy formation. Notably, the detected mass of the hot CGM is comparable to the stellar mass of these galaxies, and the implied accretion rates from the hot gas are insufficient to fuel the observed star formation in these galaxies.
- Publication:
-
American Astronomical Society Meeting Abstracts #221
- Pub Date:
- January 2013
- Bibcode:
- 2013AAS...22131304A