# BHI Colloquium

## Date:

Tuesday, May 4, 2021, 1:30pm to 2:30pm

## Location:

Abstract: The final phase of gravitational radiation from black hole binaries is the ringdown'' of the merged black holes, which occurs at a characteristic set of frequencies. Measurements of the ringdown spectrum can provide especially clean tests of the nature of the final black hole, potentially revealing violations of the famous no-hair'' theorem. The first such rough tests have recently been carried out, but precision tests using large datasets will require predictions for how the ringdown spectrum varies when the spacetime deviates from Kerr. In this talk, I will review some recent advances on measuring ringdown frequencies. I will then outline a flexible approach for calculating the shifts in the ringdown spectrum for spacetimes that deviate from Kerr.