RUI: A Multi-University Study of Rapid Variations and Transient Events at Radio Frequencies

University Of North Carolina At Asheville, Asheville NC

Investigators

Abstract

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). Dr. Brian Dennison (University of North Carolina at Asheville) and his team will use the Dedicated Interferometer for Rapid Variability (DIRV) at the Pisgah Astronomical Research Institute (PARI) to observe intraday variability (IDV) of compact extra-galactic radio sources, and simultaneously search for rare extreme scattering events (ESEs). These events are caused by intervening structures in the interstellar medium with significant density enhancements on quite small (approximately astronomical unit) scales. Interleaved with observations of extragalactic sources, a single 26-meter antenna of the interferometer will be used to monitor the intensities and rotational dynamics of pulsars. Both 26-meter antennas will host an unpointed, simultaneous search for dispersed millisecond bursts (DMBs). The research program involves commissioning DIRV, developing and installing hardware for the simultaneous "piggyback" search for DMBs, and carrying out the overall observational program. This research addresses several outstanding problems in astrophysics. The physical nature and origin of the interstellar structures responsible for ESEs are unknown. Only by discovering additional events, can the team then pursue specific concurrent observations designed to elucidate the nature and likely origin of these structures. Another major astrophysical problem arises from the single DMB discovered and credibly documented. Although theories are now being put forward to explain this event, there is a lack of observations of additional DMBs necessary to confirm the phenomenon, and elucidate its properties. Because the sole documented burst was rapid, strong, and evidently extragalactic in origin, it suggests an extremely energetic, compact source. Both ESEs and DMBs are unexplained astrophysical phenomena and this research program aims to gain insight into both. In either case, the potential exists for a transformative insight expanding our understanding of the universe. Time-intensive radio observations are not feasible within the national observatory system, in which time on highly versatile telescopes is apportioned among a large international user community. The observations to be carried out under this program add a unique and necessary component to the overall national effort in astronomy. This work also complements the setting provided by the national observatories by providing undergraduate students with an intensive hands-on research experience in which instrumentation problems are solved in the context of overarching scientific goals. Undergraduate students from three universities (University of North Carolina-Asheville, Furman University, and University of North Carolina-Pembroke) will participate in all phases of this research through an established intern program. They will work in a multi-disciplinary, collaborative environment in which instrumentation issues are central to the scientific goals.