Searching for New Particles in the Sky

Theories that seek to explain the outstanding puzzles of the Standard Model of particle physics often predict new, light, feebly-interacting particles whose discovery requires novel search strategies. Perhaps the most motivated of these particles is the QCD axion, which can elegantly solve the outstanding strong-CP problem of the Standard Model; cousins of the QCD axion can also appear, and are natural dark matter candidates. In light of these particles' small masses and weak interactions, we turn to the sky for clues of their existence. We will see how extreme astrophysical environments---from our Sun, to neutron stars, to black holes---produce large numbers of axions which lead to indirect signatures, or can be directly measured in the lab. I will discuss how rotating black holes source exponentially large numbers of gravitationally-bound axions, creating nature's laboratories for ultralight particles. These systems emit gravitational waves, allowing observatories such as LIGO to search for new particles. If the axions interact with one another, black holes instead turn into axionic beacons, populating the universe with axion waves.

Masha Baryakhtar is a James Arthur Postdoctoral Fellow at New York University, on her way to join the Physics faculty at the University of Washington as Assistant Professor. Masha received her PhD from Stanford University in 2015, followed by a  Banting Postdoctoral Fellowship at the Perimeter Institute for Theoretical Physics. She is currently pursuing the theoretical development of novel search directions for physics beyond the Standard Model, including precision laboratory searches for weakly-coupled dark matter, and astrophysical and gravitational wave observations that shed light on the presence of new, ultralight particles.