Gravitational wave tomography of the perturbative horizon
Organizers
Speaker
Neev Khera
Time
Monday, November 18, 2024 3:30 PM - 4:30 PM
Venue
A3-2-301
Online
Zoom 559 700 6085
(BIMSA)
Abstract
In the ringdown regime of binary black hole mergers the waveform is described well by a linear combination of quasinormal modes. However, the start time and accuracy of the quasinormal mode description is unclear as the waveform is susceptible to overfitting. The validity of the quasinormal mode fit can be checked by examining the interior of the spacetime in addition to waveform at null infinity. In particular, if the spacetime is truly described by quasinormal modes, the horizon of the black hole must also be described by the quasinormal modes solution. However, unlike at infinity, at the horizon there is a lot more freedom in the choice of background structure around which we perform perturbative calculations. This is a "gauge dependence" of the ringdown analysis on the horizon. Because of this gauge dependence, a quantitative comparison of the numerical studies to analytic calculations can be problematic. In this talk, I will describe a prescription that fixes this gauge dependence by finding a canonical background structure, which satisfies all the requirements of being a "good" background about which one can do perturbative calculations. In particular, there is a numerically stable method to find this background structure in a simulation. This allows us to connect perturbation theory quantitatively to the ringdown analysis of the blackhole horizon.