Quenching and Non-Standard Observables from Black Hole Superradiance

by Samuel Witte (Amsterdam)

Europe/Berlin (online only)

online only

Light bosons can form dense clouds around rotating black holes via the process known as black hole superradiance. If these bosons are non-interacting, this process can extract an order one fraction of the black hole's rotational energy over a very short timescale; consequently, the existence of rapidly rotating black holes has been used to search for, and constrain, the existence of ultralight bosons such as axions and dark photons. These bounds, however, are crucially only meaningful when the particle's interactions are sufficiently suppressed. I will show here that in many realistic models superradiance is quenched long before altering the black hole spin, invalidating the aforementioned constraints and necessitating new search strategies for such ultralight bosons. Focusing specifically on the cases of (1) axion-like particles, (2) the Standard Model photon endowed with an effective mass, and (4) the kinetically mixed dark photon, I will describe exactly which processes lead to a quenching of superradiant growth, and non-standard signatures that may nevertheless arise in the context of each of these particles.