What can we really infer from GW 150914?

TL;DR

This paper demonstrates that key parameters of GW 150914 can be estimated using basic analytical formulas from classical textbooks, highlighting the limitations of current observational constraints for inferring astrophysical details.

Contribution

It introduces a simple analytical approach to estimate black hole merger parameters from gravitational-wave data without complex simulations.

Findings

Parameters can be estimated using textbook formulas for inspiral and plunge phases.

Current LIGO data do not sufficiently constrain the system's astrophysical parameters.

Analytical estimates align closely with more complex numerical results.

Abstract

We analyze the event GW 150914 announced by the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) as the gravitational-wave emission of a black-hole binary merger. We show that the parameters of the coalescing system and of the newly formed Kerr black-hole can be extracted from basic results of the gravitational-wave emission during the inspiraling and merger phases without sophisticated numerical simulations. Our strikingly accurate estimates are based on textbook formulas describing two different regimes: 1) the binary inspiraling analysis treated in Landau and Lifshitz textbook, and 2) the plunge of a particle into a black-hole, treated in the Rees-Ruffini-Wheeler textbook. It is stressed that in order to infer any astrophysical information on the masses of the system both regimes have to be independently and observationally constrained by LIGO, which does not appear to be the case.