Parameter estimation of gravitational wave echoes from exotic compact objects

TL;DR

This paper investigates how current and future gravitational wave detectors can accurately estimate parameters of echoes from exotic compact objects, aiding in understanding horizonless geometries and strong-field gravity.

Contribution

It analyzes phenomenological templates for gravitational wave echoes and assesses the parameter estimation capabilities of interferometers with increasing model accuracy.

Findings

Current detectors can extract echo parameters with good accuracy.

Multiple interferometers can measure frequencies and damping factors at percent-level precision.

Certain echo features are most detectable with optimized configurations.

Abstract

Relativistic ultracompact objects without an event horizon may be able to form in nature and merge as binary systems, mimicking the coalescence of ordinary black holes. The postmerger phase of such processes presents characteristic signatures, which appear as repeated pulses within the emitted gravitational waveform, i.e., echoes with variable amplitudes and frequencies. Future detections of these signals can shed new light on the existence of horizonless geometries, and provide new information on the nature of gravity in a genuine strong-field regime. In this work we analyze phenomenological templates used to characterize echolike structures produced by exotic compact objects, and we investigate for the first time the ability of current and future interferometers to constrain their parameters. Using different models with an increasing level of accuracy, we determine the features that can be measured with the largest precision, and we span the parameter space to find the most favorable configurations to be detected. Our analysis shows that current detectors may already be able to extract all the parameters of the echoes with good accuracy, and that multiple interferometers can measure frequencies and damping factors of the signals at the level of percent.