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Experimental high energy astrophysics is the study of some of nature's most exotic creations, and their application to exploring fundamental physics. My research is focused on developing and flying new gamma-ray telescopes to probe these environments from space. My primary interest is the detailed measurement of radioactive nuclei produced in the inner regions of a supernova explosion. Through their conversion of gravitational energy to nuclear energy, supernovae are the dominant engines of evolution in the Universe - controlling the production of the elements making up the world around us, the internal structure of galaxies, and the acceleration of cosmic rays. The radioactive nuclei produced in these explosions emit gamma-rays of characteristic energies for each isotope. These photons serve as sensitive probes of the detailed nuclear physics in the extreme conditions at the heart of a supernova, conditions far from the laboratory environment. These nuclei also allow us to discover and study the active sites of nucleosynthesis in our Galaxy.
Gamma-ray astrophysics also touches many fields of fundamental physics, including the study of dark matter, quantum gravity, and cosmology, as well as studying matter in nature's most exotic environments. We can't see a black hole by definition, but high energy particles - accelerated by the deep gravitational well - emit gamma-rays before disappearing over the event horizon. These photons directly reflect the complex physics of particle interactions in highly-curved spacetime. Neutron stars are the ultimate balancing act between modern and classical physics, with the baryon degeneracy pressure precariously halting the collapse of the star to a black hole. The study of gamma-ray emission from the surface of these objects allows us to probe the nuclear equation of state in extremely general-relativistic conditions.
A key to these studies is the development of gamma-ray instruments with excellent sensitivity. Our group is actively involved in scientific observations with several current telescopes, as well as the development of novel gamma-ray telescopes for satellite and balloon missions.
COSI is a balloon-borne soft gamma-ray (0.2-5 MeV) telescope designed to study astrophysical sources of nuclear line emission and gamma-ray polarization. It employs a modern Compton telescope design, imaging gamma-rays through their scattering history in novel 3D tracking detectors. Implemented as a balloon payload, this telescope performs sensitive observations of positron annihilation, nuclear decays, black holes, neutron stars, GRBs, and AGN.
The GAPS experiment is designed search for evidence of dark matter by utilizing a novel detection approach to measure low energy cosmic ray antideuterons (< 0.3GeV/n). Theories predict that such low energy antideuterons are a unique signature from the self-annihilation of dark matter particles, with low astrophysical backgrounds. GAPS design and sensitivity have potential for new discoveries.
NuSTAR is the first focusing high energy X-ray satellite in orbit, providing more than two orders of magnitude improvement in sensitivity compared to previous high energy missions. NuSTAR primary science goals include conducting a survey of black holes; mapping young supernovae explosions; studying cosmic accelerators; and identifying high energy sources in our Galaxy. NuSTAR launched in June 2013.