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M. Schubnell (University of Michigan), C. Bower (Indiana University), S. Coutu (Pennsylvania State University), M. DuVernois (University of Minnesota), S. McKee (University of Michigan), D. Muller (University of Chicago), J. Musser (Indiana University), S. Nutter (Northern Kentucky University), S. Swordy (University of Chicago), G. Tarle, A. Tomasch, A. Yagi (University of Michigan)
There is strong indirect evidence for the supernova shock acceleration of galactic cosmic-ray electrons through observations of non-thermal X-rays and TeV gamma rays from supernova remnants (SNRs). Current and past electron detectors, typically flown by high altitude balloons, have been limited in their ability to study high energy electrons in the local cosmic-ray flux by their short exposure times and small apertures. To date, no measurements have been made at energies greater than 2 TeV. Yet the detection of high-energy electrons would be extremely significant, yielding information about the spatial distribution of nearby cosmic ray sources. High-energy electrons lose energy rapidly during propagation in the Galaxy through synchrotron and inverse Compton processes and thus TeV electrons reaching the solar system have to originate at distances < 1 kpc, leaving few known supernova remnants from which these particles could originate. The spectral shape of high-energy electrons should, therefore, be strongly affected by the number of nearby sources, and their distance distribution. Conversely, if no such features in the high-energy electron spectrum are observed it will call into question our understanding of cosmic ray sources and propagation. The balloon-borne Cosmic Ray Electron Synchrotron Telescope (CREST) will detect high-energy electrons by measuring the X-ray synchrotron photons generated by these electrons in the Earth’s magnetic field. This technique results in a substantial increase in the acceptance and sensitivity of the apparatus compared to the traditional direct detection of electrons. The instrument will consist of a 2m x 2m array of BGO crystals. Simulation studies indicate that with an ultra-long duration (100 day) flight, as many as 250 such electrons will be detected with energies greater than 2 TeV, with an expected background of only 1 event. A prototype instrument is currently being developed and will be flown in 2005 on a conventional balloon. The full CREST instrument will be flown in 2007 in Antarctica. This work is supported by a grant from the National Aeronautics and Space Administration.
The author(s) of this abstract have provided an email address for comments about the abstract: schubnel@umich.edu
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Bulletin of the American Astronomical Society, 36 #3
© 2004. The American Astronomical Soceity.