Astrophysics, Relativity, and Cosmology Seminar - Roman Berenes (UIUC) - "Black Hole Perturbations: Gravitational Waves and Tidal Response"

I will review recent analytic progress in black hole perturbation theory, with applications to gravitational waves and tidal response. First, I will present explicit results for reconstructing metric perturbations of the Kerr black hole, a key step in modeling gravitational-wave signals for LIGO and LISA. I will then focus on tidal Love numbers, which characterize an object's response to an external tidal field. I will discuss the symmetries of static perturbations that explain the vanishing of black hole Love numbers in general relativity, and how the tidal response changes for exotic compact objects. Using examples such as gravastars and thin-shell wormholes, I will explore how Love numbers depend on interior geometry and material properties, and how they behave as the object approaches the black hole limit. These results illustrate how tidal response can help distinguish objects whose exterior geometries closely resemble that of a black hole.