VERITAS Observations Of M~31 (The Andromeda Galaxy)

Understand

Diffuse gamma rays are tracers of cosmic rays, providing information on their origin, interaction and diffusion through a galaxy.

• M 31 (the Andromeda Galaxy) is the closest spiral galaxy to the Milky Way (d = 780 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 54 hours of observations of M 31 and an upper limit on the VHE flux is presented along with an updated \Fermis (0.1 < E < 300 GeV) analysis.