(The VERITAS Collaboration)
The origin of very high energy (VHE) cosmic rays is one of the oldest and deepest puzzles of astrophysics, and solving this fundamental problem requires an understanding of particle production and acceleration in astrophysical sources. In this talk, we attempt to find clues about the origin of cosmic rays by looking at the VHE gamma ray emission from one of the weakest known extragalactic sources, the starburst galaxy M82, observed with VERITAS and the Fermi Gamma-ray space telescope. Since its first detection of M82 in 2009, VERITAS has almost doubled the exposure, and developed advanced analysis methods with improved sensitivity. We look at these latest results, extending the VERITAS gamma ray spectrum to lower energies, and discuss the implications of the combined Fermi-LAT and VERITAS spectrum for the production of cosmic rays in M82.