# Echoes from the scattering of wavepackets on wormholes

## TL;DR

This paper investigates wavepacket scattering on wormholes to understand echo signals, revealing that echoes are frequency-dependent and that the cavity affects gravitational wave polarization, with a publicly available simulation code.

## Contribution

It introduces a detailed analysis of wavepacket scattering on wormholes, highlighting echo characteristics and polarization effects, using the geometrical optics approximation.

## Key findings

- Echo amplitude is significant only in a narrow frequency band.
- The wormhole cavity alters the polarization of gravitational waves.
- The study provides a publicly available code for further scattering analysis.

## Abstract

It has been recently shown that observing pulses isolated from the gravitational radiation transient (also known as echoes) would prove the existence of exotic compact objects (ECOs). Many features of the ringdown signal can be reproduced by simulating a scattering problem instead of the full coalescence of ECOs. In this paper, we study the dynamics of scalar and tensor wavepackets colliding against a spherically symmetric Morris-Thorne wormhole. Our aim is to extract the features of the time-dependent scattering solutions inside and outside the effective potential cavity in addition to their asymptotic behavior. Using the geometrical optics approximation, we show that the amplitude of the echoes is only large enough in a narrow bandwidth of frequency space. Additionally, we show that the cavity modifies the polarization of the asymptotic gravitational wave solutions. The computer code used to produce these results is publicly available for further applications, including scattering and accretion processes.