University of Maryland
Atlantic Building, Room 2400
4:30 PM Monday, January 29, 2007
Coffee, Tea & Snacks 4:15-4:30 PM

Andrew Smith
University of Maryland
Discovery of TeV Gamma-Ray Emission from the Cygnus Region of the Galaxy

The diffuse gamma radiation arising from the interaction of cosmic ray particles with matter and radiation in the Galaxy is one of the few probes available to study the origin of the cosmic rays. Data from the Milagro gamma-ray observatorya water Cherenkov detector that continuously views ~2 sr of the overhead skyshows that the brightest extended region in the entire northern sky is the Cygnus region of the Galactic plane. The TeV image of the Cygnus region contains at least one new source MGRO J2019+37, which is 10.9 standard deviations above the isotropic background, as well as correlations with the matter density in the region. However, the gamma-ray flux from the Cygnus region (after excluding MGRO J2019+37) as measured at ~12 TeV exceeds that predicted from a model of cosmic ray production and propagation. This observation indicates the existence of either hard-spectrum cosmic-ray sources and/or unresolved sources of TeV gamma rays in the region.

Sponsored by: Department of Physics and the Institute for Physical Science and Technology, University of Maryland. For information call Victoria at (301) 405-4811 or go to the UMD Space Physics group seminar web site.

There is free parking after 4:00 PM in lot B (the big parking garage across the street from the ATL building). There are a limited number of spaces in lot Q next to the new ATL wing with free parking after 4PM even when there is a basketball game on campus.