Profiling stellar environments of gravitational wave sources

TL;DR

This paper demonstrates that gravitational wave measurements alone can infer detailed properties of the stellar environments hosting compact binary coalescences, enhancing understanding of their formation and evolution.

Contribution

It introduces a method to extract host environment parameters from GW data without electromagnetic counterparts, applicable across various astrophysical settings and observatories.

Findings

Environment parameters can be inferred from GW kinematics.

Method works for different host environments like clusters and galactic nuclei.

Applicable to multiple GW detectors including LIGO, LISA, and DECIGO.

Abstract

Gravitational waves (GWs) have enabled direct detections of compact binary coalescences (CBCs). However, their poor sky localisation and the typical lack of observable electromagnetic (EM) counterparts make it difficult to confidently identify their hosts, and study the environments that nurture their evolution. In this work, we show that $\textit{detailed}$ information of the host environment (e.g. the mass and steepness of the host potential) can be directly inferred by measuring the kinematic parameters (acceleration and its time-derivatives) of the binary's center of mass using GWs alone, without requiring an EM counterpart. We consider CBCs in various realistic environments such as globular clusters, nuclear star clusters, and active galactic nuclei disks to demonstrate how orbit and environment parameters can be extracted for CBCs detectable by ground- and space-based observatories, including the LIGO detector at A+ sensitivity, Einstein Telescope of the XG network, LISA, and DECIGO, $\textit{on a single-event basis}$. These constraints on host stellar environments promise to shed light on our understanding of how CBCs form, evolve, and merge.