Comment on "Some exact quasinormal frequencies of a massless scalar field in Schwarzschild spacetime"

TL;DR

This paper critically examines a recent claim of a new quasinormal mode branch in Schwarzschild spacetime, identifies flaws in the original proof, provides counterexamples, and finds no evidence supporting the new modes through alternative methods.

Contribution

The paper refutes the existence of the proposed new quasinormal mode branch by analyzing the original proof, providing counterexamples, and applying alternative methods.

Findings

The original proof contains flaws.

Counterexamples invalidate the new mode branch.

Alternative analyses do not find the proposed modes.

Abstract

A new branch of quasinormal modes for a massless scalar field propagating on the Schwarzschild spacetime was recently announced [1807.04513]. We review the quasinormal modes characterisation and arguments and identify the flaws in their proof. Then, we preset explicit counterexamples to such arguments. Finally, we study the modes via alternative methods and do not find the new branch. We conclude against their interpretation.