The Phase Space of Low-Mass Binary Compact Objects from LIGO-Virgo-KAGRA Catalog: Hints on the Chances of Different Formation Scenarios

TL;DR

This paper extends a phase space analysis to low-mass compact objects using GW data, providing a new framework to distinguish their formation scenarios and improve understanding of their origins.

Contribution

It introduces a novel phase space framework for low-mass compact objects, enabling probabilistic identification of their formation mechanisms from GW observations.

Findings

First phase space demonstration for low-mass compact objects

Probabilistic assessment of formation scenarios including neutron stars, black holes, and primordial black holes

Highlights degeneracies due to modeling uncertainties

Abstract

Gravitational wave (GW) observations have significantly advanced our understanding of binary compact object (BCO) formation, yet directly linking these observations to specific formation scenarios remains challenging. The BCO phase space provides a robust and data-driven approach to discover the likely formation scenarios of these binaries. In this study, we expand the previously introduced binary black hole phase space technique to encompass low-mass compact objects (LMCOs), establishing a novel framework to investigate their diverse formation mechanisms. Applying this approach to selected low-mass events $(\lesssim 5 M_\odot)$ from the GWTC-3 catalog and the recently observed GW230529 event, we show for the first time the phase space demonstration of the LMCOs and find the associated probabilities for different formation scenarios including neutron star, astrophysical black hole, or primordial black hole. Our analysis includes the astrophysical modelling uncertainties in and how it causes degeneracy between different formation scenarios. In future, with improvements in GW detector sensitivity and with detection of more GW events, the LMCO phase space framework will significantly strengthen our capacity to associate more likely formation scenarios over the other, thereby refining our understanding of compact object formation for both astrophysical and primordial scenarios, and its evolution across the cosmic redshift.