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July 29, 2015 to August 6, 2015
World Forum
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VERITAS Observations of M31 (the Andromeda Galaxy)

Jul 30, 2015, 3:30 PM
Mississippi Foyer (World Forum)

Mississippi Foyer

World Forum

Churchillplein 10 2517 JW Den Haag The Netherlands
Board: 51
Poster contribution GA-EX Poster 1 GA


Ralph Bird (UCD Dublin)


Diffuse gamma rays are tracers of cosmic rays, providing information on their origin and diffusion. M 31 (the Andromeda Galaxy) is the closest spiral galaxy to the Milky Way (d = 750 kpc) and is very well studied at all wavelengths, thus it is a prime target for the study of diffuse gamma-ray emission. The very-high-energy (VHE, E > 100 GeV) gamma-ray observatory VERITAS has conducted 45 hours of observations of M 31 and an upper limit on the VHE flux will be presented. An updated Fermi-LAT (100 MeV < E < 300 GeV) analysis will also be presented. These observations will be compared with predictions of the gamma-ray flux derived from the inelastic scattering of VHE cosmic rays of the interstellar medium (ISM) and the interstellar radiation field. M 31 provides an ideal opportunity to probe these mechanisms. Its proximity and spatial extent, significantly larger than the VERITAS point spread function but smaller than the field-of-view, enables the star-forming ring, 10 kpc from the galaxy core, with its dense ISM and numerous supernova remnants to be resolved.
Registration number following "ICRC2015-I/" 884
Collaboration VERITAS

Primary author

Ralph Bird (UCD Dublin)

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