The 2009 Fermi Symposium

Fermi LAT Detection of Gamma-ray Emission from Starburst Galaxies M82 and NGC 253

Keith Bechtol, SLAC/KIPAC/Stanford

Abstract:

Starburst galaxies host regions of rapid stellar formation where cosmic rays should be efficiently accelerated according to models of particle acceleration at supernovae remnant shocks. The combination of enhanced cosmic-ray intensity amidst regions of dense gas and interstellar radiation fields is expected to produce sufficient gamma-ray luminosity to be observed over extragalactic distance scales by the current generation of gamma-ray intruments. We report the detection of starburst galaxies M82 and NGC 253 by the Fermi LAT. Both sources exhibit steady, point-like emission above 200 MeV at fluxes consistent with gamma-ray production dominated by hadronic cosmic-ray interactions, thereby establishing an observational connection between massive star-formation and diffuse gamma-ray emission.