# BHI Colloquium

## Date:

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

## Location:

Aaron Zimmerman (Physics) - University of Texas

Title: Testing the nature of black holes: towards precision ringdown tests

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.

Bio: Aaron Zimmerman received his bachelor's degree at the University of New Mexico, before going on to graduate studies at Caltech under advisor Yanbei Chen. After completing his PhD in 2013, Aaron moved to the Canadian Institute for Theoretical Physics, first as a postdoc and then as a senior research associate. He joined the faculty at the University of Texas at Austin in 2018. Aaron has worked on diverse topics in black hole perturbation theory, numerical relativity, and gravitational wave data analysis. Aaron is a member of the LIGO Scientific Collaboration, where he currently serves as co-chair of the Parameter Estimation working group.