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The 2009 Fermi Symposium

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

Keith Bechtol, SLAC/KIPAC/Stanford


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.