Bernstein spectral method for quasinormal modes and other eigenvalue problems

Abstract Spectral methods are now common in the solution of ordinary differential eigenvalue problems in a wide variety of fields, such as in the computation of black hole quasinormal modes. Most of these spectral codes are based on standard Chebyshev, Fourier, or some other orthogonal basis functio...

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Main Authors: Sean Fortuna, Ian Vega
Format: Article
Language:English
Published: SpringerOpen 2023-12-01
Series:European Physical Journal C: Particles and Fields
Online Access:https://doi.org/10.1140/epjc/s10052-023-12350-9
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author Sean Fortuna
Ian Vega
author_facet Sean Fortuna
Ian Vega
author_sort Sean Fortuna
collection DOAJ
description Abstract Spectral methods are now common in the solution of ordinary differential eigenvalue problems in a wide variety of fields, such as in the computation of black hole quasinormal modes. Most of these spectral codes are based on standard Chebyshev, Fourier, or some other orthogonal basis functions. In this work we highlight the usefulness of a relatively unknown set of non-orthogonal basis functions, known as Bernstein polynomials, and their advantages for handling boundary conditions in ordinary differential eigenvalue problems. We also report on a new user-friendly package, called SpectralBP, that implements Berstein-polynomial-based pseudospectral routines for eigenvalue problems. We demonstrate the functionalities of the package by applying it to a number of model problems in quantum mechanics and to the problem of computing scalar and gravitational quasinormal modes in a Schwarzschild background. We validate our code against some known results and achieve excellent agreement. Compared to continued-fraction or series methods, global approximation methods are particularly well-suited for computing purely imaginary modes such as the algebraically special modes for Schwarzschild gravitational perturbations.
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spelling doaj.art-aabdae32d04e4b1e882d9efd6d4b59552024-03-31T11:31:26ZengSpringerOpenEuropean Physical Journal C: Particles and Fields1434-60522023-12-01831212710.1140/epjc/s10052-023-12350-9Bernstein spectral method for quasinormal modes and other eigenvalue problemsSean Fortuna0Ian Vega1National Institute of Physics, University of the Philippines DilimanNational Institute of Physics, University of the Philippines DilimanAbstract Spectral methods are now common in the solution of ordinary differential eigenvalue problems in a wide variety of fields, such as in the computation of black hole quasinormal modes. Most of these spectral codes are based on standard Chebyshev, Fourier, or some other orthogonal basis functions. In this work we highlight the usefulness of a relatively unknown set of non-orthogonal basis functions, known as Bernstein polynomials, and their advantages for handling boundary conditions in ordinary differential eigenvalue problems. We also report on a new user-friendly package, called SpectralBP, that implements Berstein-polynomial-based pseudospectral routines for eigenvalue problems. We demonstrate the functionalities of the package by applying it to a number of model problems in quantum mechanics and to the problem of computing scalar and gravitational quasinormal modes in a Schwarzschild background. We validate our code against some known results and achieve excellent agreement. Compared to continued-fraction or series methods, global approximation methods are particularly well-suited for computing purely imaginary modes such as the algebraically special modes for Schwarzschild gravitational perturbations.https://doi.org/10.1140/epjc/s10052-023-12350-9
spellingShingle Sean Fortuna
Ian Vega
Bernstein spectral method for quasinormal modes and other eigenvalue problems
European Physical Journal C: Particles and Fields
title Bernstein spectral method for quasinormal modes and other eigenvalue problems
title_full Bernstein spectral method for quasinormal modes and other eigenvalue problems
title_fullStr Bernstein spectral method for quasinormal modes and other eigenvalue problems
title_full_unstemmed Bernstein spectral method for quasinormal modes and other eigenvalue problems
title_short Bernstein spectral method for quasinormal modes and other eigenvalue problems
title_sort bernstein spectral method for quasinormal modes and other eigenvalue problems
url https://doi.org/10.1140/epjc/s10052-023-12350-9
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