qnm: A Python package for calculating Kerr quasinormal modes, separation constants, and spherical-spheroidal mixing coefficients

Leo C. Stein

J. Open Source Softw., 4(42), 1683 (2019) [arXiv:1908.10377] [doi:10.21105/joss.01683]

qnm is an open-source Python package for computing the Kerr quasinormal mode frequencies, angular separation constants, and spherical-spheroidal mixing coefficients. The qnm package includes a Leaver solver with the Cook-Zalutskiy spectral approach to the angular sector, and a caching mechanism to avoid repeating calculations. We provide a large cache of low modes, which can be downloaded and installed with a single function call, and interpolated to provide good initial guess for root-polishing at new values of spin.