Are all Binary Black Holes Detected by LIGO-Virgo-KAGRA Following the Universal Time-Delay Distributions? Probably Not
Authors
Samsuzzaman Afroz
Navdha Navdha
Suvodip Mukherjee
Abstract
The delay time distribution (DTD) of binary black hole (BBH) mergers encodes the evolutionary link between the formation history and gravitational-wave (GW) emission. We present a non-parametric reconstruction of the mass-dependent DTD using the BBHs from the GWTC-4 that avoids restrictive assumptions of only power-law forms. Our analysis reveals for the first time the signature for mass-dependent evolutionary pathways: lower-mass systems ($20$-$40\,M_\odot$) are consistent with a scale-invariant DTD, whereas higher-mass BBHs ($40$-$100\,M_\odot$) provide the first direct tentative evidence of DTD that deviate from simple power laws, with a pronounced preference for rapid mergers around $2-6$ Gyrs. These findings reveal the advantage of the non-parametric technique in reconstructing the mass-dependent DTD and discovering for the first-time the presence of a potential time-scale associated with high-mass GW events.
