Localization of transient gravitational wave sources: beyond triangulation

TL;DR

This paper enhances gravitational wave source localization by integrating polarization consistency and astrophysical source distributions, reducing sky area uncertainty by 40% and improving the accuracy of polarization state determination.

Contribution

It introduces a method that extends timing-based localization to include polarization and source distribution information, significantly improving localization precision.

Findings

Localization area reduced by 40% compared to timing-only methods.

Most sources are reconstructed as circularly polarized or face-on.

Enhanced localization aids electromagnetic follow-up efforts.

Abstract

Rapid, accurate localization of gravitational wave transient events has proved critical to successful electromagnetic followup. In previous papers we have shown that localization estimates can be obtained through triangulation based on timing information at the detector sites. In practice, detailed parameter estimation routines use additional information and provide better localization than is possible based on timing information alone. In this paper, we extend the timing based localization approximation to incorporate consistency of observed signals with two gravitational wave polarizations, and an astrophysically motivated distribution of sources. Both of these provide significant improvements to source localization, allowing many sources to be restricted to a single sky region, with an area 40% smaller than predicted by timing information alone. Furthermore, we show that the vast majority of sources will be reconstructed to be circularly polarized or, equivalently, indistinguishable from face-on.