Echoes from Classical Black Holes

TL;DR

This paper investigates scalar wave echoes from dyonic black holes in Einstein-Maxwell gravity with a quasi-topological electromagnetic term, revealing conditions for double-peaked potentials and resulting quasinormal mode echoes.

Contribution

It introduces the study of scalar wave echoes in dyonic black holes with extended electromagnetic terms, highlighting the conditions for double-peak potentials and echo phenomena.

Findings

Effective potential can have double peaks under certain parameters.

Echo frequencies are approximately twice those of initial waves inside the peaks.

Black holes satisfy the dominant energy condition and exhibit quasinormal mode echoes.

Abstract

We study echoes of free massless scalar from dyonic black holes in Einstein-Maxwell gravity extended with the quasi-topological electromagnetic term. These asymptotically-flat black holes all satisfy the dominant energy condition. We find that for suitable parameters, the effective potential can have double peaks and consequently echoes of quasinormal modes arise. In general the echo frequency associated with the initial wave packet released inside the two peaks is about twice the frequency of the one released outside.