Comment on "Probing gravitational wave polarizations with signals from compact binary coalescences"

TL;DR

This paper critiques a previous claim that a single gravitational wave detection can distinguish polarization types, clarifying that multiple detections are necessary unless the wave propagates in a specific direction.

Contribution

It corrects a mistake in prior analysis and emphasizes the need for multiple detections to differentiate gravitational wave polarizations.

Findings

Single detection cannot reliably distinguish polarization types

Multiple detections enable polarization differentiation

Directional dependence affects polarization analysis

Abstract

In a recent paper "Probing gravitational wave polarizations with signals from compact binary coalescences" (arXiv:1710.03794 [gr-qc]) the authors argue that a single detection of gravitational wave by the LIGO-Virgo network is capable to distinguish between pure tensor and pure vector polarizations of gravitational waves. Here we point out a mistake in the author's analysis and show that such differentiation is possible only in the unlikely event when gravitational wave propagates in the direction of interferometer zero response for the tensor or vector polarizations. Nevertheless, the LIGO-Virgo network can distinguish between pure tensor and pure vector polarizations by collecting statistics, as we showed in Phys. Scr. 92, 125001 (2017).