Compact object binaries, consisting of neutron stars and black holes, represent one of the most likely sources of gravitational waves to be detected by LIGO and future gravitational wave observatories. Â This project will design computer models to study gravitational radiation from compact object binaries. Â This will include studying how the internal structure of neutron stars affects the gravitational radiation emitted in a binary merger. Â Additional work will investigate opportunities for multiple messenger astronomy, in which data from several types of observations are combined to obtain a more complete picture. Â In particular, this project will study possible emission of electromagnetic radiation and neutrinos from the merger of neutron stars and black holes.
This research is of broad interest reaching beyond physicists to astrophysicists, mathematicians, and the general public (for whom movies will be posted to the web). Â The connection of gravitational, electromagnetic and neutrino data from black hole and neutron star mergers will significantly advance our understanding of some of the most intriguing processes in the universe. Â This work will provide valuable candidate waveforms for gravitational wave observatories, including LIGO. Â As part of a multinational effort to compare such waveforms, this work will be especially valuable to the gravitational wave community in their efforts to detect this radiation. Â Information that comes from these gravitational waves will lead to a better understanding of the internal structure of neutron stars and matter at nuclear densities. Â The activities described here will provide educational and training opportunities for undergraduate and graduate students, including individuals from underrepresented groups. Â This work uses the HAD computational infrastructure, and thus supports this broadly useful, publicly available software for scientific computing.
Our work on neutron stars and black holes has advanced on several fronts. In the last year we have worked to better understand some of the processes by which a merged binary neutron star system can cool. In particular, in themerger process the material the comprises the two neutron stars can be heated to very high temperatures and the formation of neutrinos can be a key aspect to cooling the merged, hypermassive neutron star and transporting energy away from the system. This cooling via neutrinos has been incorporated into our simulations and continues to be tested and explored. We have also worked to better understand the overall structure of the magnetic field present in neutron stars. For very strongly magnetized neutron stars such as magnetars, it is essentially unknown what the size is of the magnetic field that resides in the interior. Working with both mathematical models and numerical calculations based on these models, we have made substantial headway in understanding the interior magnetic fields of these special types of magnetized neutron stars. We have come to learn and realize that these fields deep in the interior of the star can be as much as a hundred times larger than the magnetic fields that we deduce on the surface. This is potentially very exciting as it may provide a means of deforming such stars into elongated shapes that could affect the types of radiation they emit. We continue to look at these sorts of questions.
