Phase space of binary black holes from gravitational wave observations to unveil its formation history
Phys. Rev. D 112, 023531 – Published 17 July, 2025
DOI: https://doi.org/10.1103/7zc2-g9vq
Abstract
Gravitational wave (GW) sources offer a valuable window to the physical processes that govern the formation of binary compact objects (BCOs). However, deciphering such information from GW data is substantially challenging due to the difficulty in mapping from the space of observation to the space of numerous theoretical models. We introduce the concept of BCO phase space that connects the observable space to the evolution trajectories of the BCO formation channels with cosmic time and apply it to the third GW transient catalog that brings new insights into probable astrophysical formation scenarios of nearly 90 events. Our study reveals that two events, GW190425 and GW230529, show an overlap with a BCO phase space trajectory of the same formation channel arising from a subsolar mass black hole scenario that has grown into a higher mass by accretion, hinting towards the common primordial origin of both these sources. Though the actual formation channel is yet to be confirmed, with the availability of more GW events, the BCO phase space can delve into distinguishing features of different formation channels for both astrophysical and primordial origin and opens the possibility of bringing new and deeper insights on the formation and evolution of BCOs across all observable masses over most of the cosmic time.
