Ringdown

The oscillation modes of black holes are called “quasinormal modes” (QNMs; “quasi” because they are damped by the emission of gravitational radiation). These quantities are of interest in gravitational-wave astronomy, to test the so-called “no-hair theorem” of general relativity, and in the context of the gauge-gravity duality. Here you can find data for:

• the QNM spectrum of Schwarzschild (anti-de Sitter) and Kerr black holes.
• the excitation factors of Kerr quasinormal modes.
• the spherical-spheroidal mixing coefficients between the angular functions that correspond to each mode (spin-weighted spheroidal harmonics) and the spin-weighted spherical harmonics normally used to decompose gravitational radiation.

You can also find Mathematica notebooks to compute some of these quantities. The data and routines are freely available, but please reference the original work(s). Important caveat: the calculations of Kerr QNM frequencies presented here are unreliable very close to the Kerr extremal limit (roughly, when $a/M\geq 0.999$). The near-extremal regime is discussed in arXiv:1212.3271 and arXiv:1307.8086; see also arXiv:1410.7698.

I would like to thank Oscar Dias, Mahdi Godazgar and Jorge Santos for providing Kerr-Newman quasinormal mode data from arXiv:1501.04625.