Spatially-resolved Spectral Analysis of the Hot Gaseous Emission in the M31 Bulge

Mihoko Yukita, Johns Hopkins University
Jimmy A. Irwin, University of Alabama - Tuscaloosa
Ka-Wah Wong, Minnesota State University Mankato
Evan T. Million, University of Alabama - Tuscaloosa


We report results from a deep, ~400 ks archival Chandra ACIS study of the galactic bulge in M31. We aim to greater understand the properties of the hot gas in galactic bulges, which play an important role in galaxy evolution via outflows. Detailed, spatially resolved, spectral analysis of the central 3 arcmin reveal that the hot gas is well characterized by a two-temperature, collisionally ionized, optically-thin plasma model with temperatures k 0.2 and 0.5 keV. The radial temperature profile of the k 0.2 keV component is approximately flat, while the temperature profile of the k 0.5 component contains a potential small central peak. The surface brightness of the k 0.2 keV gas follows a beta model distribution that is comparable to the stellar distribution of the bulge. The surface brightness of the hotter k 0.5 keV component follows a significantly different trend. We discuss the interpretation of our results.