The detection of the Fermi Bubbles suggests that spiral galaxies such as the Milky Way can undergo active periods. Using gamma-ray observations, we can investigate the possibility that such structures are present in other nearby galaxies. We have analyzed the region around the Andromeda Galaxy (Messier Catalog M31) for signs of bubble-like emission using TeV gamma-ray data recorded by the High-Altitude Water Cherenkov Observatory. We fit a model consisting of two 6 kpc bubbles symmetric about and perpendicular to the M31 galactic plane and assume a power-law distribution for the gamma-ray flux. We compare the emission from these bubble regions to that expected from structures similar to the Fermi Bubbles found in the Milky Way. No significant emission was observed. We report upper limits on the TeV flux from Fermi Bubble structures in M31.
R. Rubenzahl, S. BenZvi, J. Wood, et. al.
Fri, 11 Aug 17
Comments: Presented at the 35th International Cosmic Ray Conference (ICRC2017), Bexco, Busan, Korea. See arXiv:1708.02572 for all HAWC contributions