Accurately Modeling Synchrotron Emission from Trans-Relativistic Transients

The night sky may seem eternal and unchanging, but when viewed carefully, it is incredibly dynamic. Many stars end their lives in violent explosions that produce intense flashes of light analogous to cosmic fireworks. Studying such cosmic explosions holds enormous potential for learning about the most extreme states of matter, the origin of elements in the periodic table, and the evolution of the cosmos. In recent years, puzzling new classes of cosmic explosions are being discovered where the explosion is so energetic that the resulting blast wave expands at nearly the speed of light.. A 3-year research program led by investigators at the University of Minnesota-Twin Cities aims to develop novel and accurate theoretical models that will be used to interpret existing and upcoming observations of relativistic cosmic explosions. A primary task of this project will be to develop code that accurately calculates how light is produced and escapes such explosions. Award activities will inspire public interest, increase public participation, and train the next generation of scientists through a summer outreach program within the Minnesota state parks network, enhancing the elementary school astronomy curriculum of the Como Planetarium, and the training of undergraduate and postgraduate students. Theoretical models of cosmic explosions will incorporate a full treatment of relativistic effects, which are critical when velocities are comparable to the speed of light. This will extend existing models, which either treat these effects using simplistic approximations or neglect them altogether. After developing this code, the investigators will apply the model to a wide range of observed relativistic explosions. The predictions of this model will allow accurate and unbiased inferences of the explosion properties of fast blue optical transients, the local environments of supermassive black holes (using data from jetted tidal-disruption events), and the properties of merging neutron stars, which can shed light on the behavior of nuclear matter at the highest densities in the Universe. 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.