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Date: September 20, 2017
Speaker: Theresa J. Brandt, NASA Goddard Space Flight Center
Topic: Galactic Cosmic Rays: From Earth to Sources
Time and Location: 1:00 p.m., with Q&A to follow in a 1st floor conference room at the American Center for Physics (www.acp.org), 1 Physics Ellipse, College Park, MD-- off River Rd., between Kenilworth Ave. and Paint Branch Parkway.
Abstract: For over 100 years we have known that cosmic rays come from outer space, yet proof of their origin, as well as a comprehensive understanding of their acceleration, remains elusive. Direct detection of high energy (up to 10^15eV), charged nuclei with experiments such as the balloon-borne Super Trans-Iron Galactic Element Recorder (TIGER) have provided insight into these mysteries through measurements of cosmic ray abundances over Antarctica. The abundance of rare heavy elements with respect to certain intrinsic properties suggests that cosmic rays include a component of massive star ejecta.
Supernovae and their remnants (SNe & SNRs), often occurring at the end of a massive star's life or in an environment including massive star material, are one of the most likely candidates for sources accelerating galactic cosmic ray nuclei up to the requisite high energies. The Fermi Gamma-ray Space Telescope Large Area Detector (Fermi LAT) has improved our understanding of such sources by widening the window of observable energies and thus our view into potential sources' energetic processes. Since Fermi LAT surveys the whole sky, we have created the first systematic study of GeV emission in all regions containing known SNRs. Not only does this catalog, in combination with the wealth of multiwavelength data available, allow us to constrain SNRs' ability to accelerate cosmic rays, but it also provides statistically-motivated insight into the inner workings of GeV-emitting SNRs.
Biography: After several undergraduate research experiences in astronomy and various disciplines of physics, Dr Brandt joined the Ohio State University astrophysics graduate program, working on the CREAM experiment. Having measured Cosmic Ray Energetics And Mass using balloon-borne instrumentation in Antarctica, Dr Brandt shifted to indirect forms of cosmic ray study using high energy gamma-rays with the Fermi Gamma-ray Space Telescope at the Institute de Recherche en Astrophysique et Planétologie and the Université de Toulouse, France. Now at the NASA Goddard Space Flight Center, Dr Brandt combines direct and indirect detection techniques to shed light on the origins and propagation of cosmic rays as well as measuring and improving our understanding of energetic processes in the universe. Dr Brandt was recently appointed Deputy Chief Scientist of NASA's Physics of the Cosmos Program.