NSF Award
2307394
A central issue in astrophysics today is understanding the merging of neutron stars (NS), highly compact celestial objects, or NS with black holes (BH). Such mergers produce gravitational waves (GW), a counterpart electromagnetic signal, and ultimately the heaviest atomic elements in the universe. In addition to counterparts produced during and after the merger of such systems, it might also be possible to create prompt transient events before the collision, due to the presence of strong magnetic fields in the inspiraling NS. Such a precursor event was recently reported for the long gamma-ray burst GRB 211211A. Understanding whether and how such transients can be launched will be crucial both as an additional tool for prompt sky localization by aiding follow-up searches for GW afterglows, as well as constraining currently inaccessible parameters such as the magnetic field strengths in the pre-merger system. A research collaboration between California Institute of Technology and the University of Maryland, College Park, will investigate these issues through a program of computer simulations in general relativity and kinetic theory. The project will provide training for undergraduate and graduate students and include the creation of a summer school at the intersection of computational relativity and plasma astrophysics. <br/><br/>The researchers will perform the first numerical simulations of the crustal shattering mechanism, which is the leading hypothesis for the production of a precursor. To uncover the actual emission mechanism in the system, they will calculate the efficiency of coherent emission mechanisms associated with mergers of plasmoids in relativistic magnetic reconnection, in regimes applicable to the magnetospheres of compact object mergers and magnetars. Finally, they will explore a novel radiative regime of reconnection in strong magnetic fields and calculate the spectrum of escaping high-energy X-ray photons. The results (including predicted frequency ranges and luminosity scalings with system parameters) and simulation codes provided by the research team will be directly relevant for multi-messenger observations of NS-NS and NS-BH mergers. This summer school program will fill a gap in the training opportunities of early career scientists, preparing them for research forefront of relativistic and multi-messenger astrophysics. In addition, postdoctoral scholars and graduate students supported by this project will receive extensive professional, educational, and equity, diversity, and inclusion training, including transferable skills acquired through work on this project. This will enable them to be well-positioned throughout their careers to contribute also to technical advances and discoveries in other areas of science and engineering. This award advances the goals of the Windows on the Universe Big Idea.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
