UC Riverside

With all of the success of the Standard Model (SM) of particle physics there are still looming inconsistencies between the model and observations. The open questions in high energy physics motivate models of physics beyond the SM. Of the natural phenomena still not explained by the SM, perhaps the biggest open question is the nature of dark matter. To date, there have been no conclusive direct detection signals of dark matter and what we know about the mysterious substance remains relegated to gravitational effects dark matter has on ordinary matter.This work is focused on studying the constraints that astrophysical systems can place on models of dark matter. In particular, this work studies models of dark matter that exhibit self-interactions. It is shown here how inelastic models of dark matter which self-interact through the exchange of a light mediator can have observational effects on halo dynamics. Self-interactions can play an important role in annihilation signals in the central regions of halos when a black hole is present. It has been previously shown that the constraints from annihilation signals rule out much of the WIMP parameter space. It is shown here that mod- els of self-interacting dark matter can significantly weaken these constraints, reviving much of the parameter space. In the very dense environment of a Neutron Star (NS), scattering events between dark matter and standard model particles can impart a significant amount of thermal energy. This work shows how the inelastic model of self-interacting dark mat- ter can be probed using NS heating. Inelastic models of dark matter have previously been shown to be able to escape direct detection signals. It is shown here that in the parameter space where direct detection is no longer sensitive to inelastic dark matter, NS heating can still probe the model. In other parts of the parameter space, NS heating is superior to or complementary to terrestrial direct detection experiments. Given the absence of terrestrial direct detection signals, looking towards astrophysical systems as particle detectors is a very interesting and exciting avenue to probe the nature of dark matter.