Astrophysical Prior Information and Gravitational-wave Parameter Estimation

TL;DR

This paper examines how electromagnetic observations can aid gravitational-wave parameter estimation, finding limited improvements mainly for the primary spin, and concludes that such additional information offers modest benefits for intrinsic parameter measurement.

Contribution

The study assesses the maximal impact of perfect extrinsic parameter knowledge on gravitational-wave intrinsic parameter estimation, revealing limited improvements.

Findings

Modest improvement in primary spin measurement.

Electromagnetic data does not significantly enhance intrinsic parameter estimates.

Extrinsic parameter knowledge offers limited benefit for gravitational-wave analysis.

Abstract

The detection of electromagnetic counterparts to gravitational waves has great promise for the investigation of many scientific questions. It has long been hoped that in addition to providing extra, non-gravitational information about the sources of these signals, the detection of an electromagnetic signal in conjunction with a gravitational wave could aid in the analysis of the gravitational signal itself. That is, knowledge of the sky location, inclination, and redshift of a binary could break degeneracies between these extrinsic, coordinate-dependent parameters and the physical parameters, such as mass and spin, that are intrinsic to the binary. In this paper, we investigate this issue by assuming a perfect knowledge of extrinsic parameters, and assessing the maximal impact of this knowledge on our ability to extract intrinsic parameters. However, we find only modest improvements in a few parameters --- namely the primary component's spin --- and conclude that, even in the best case, the use of additional information from electromagnetic observations does not improve the measurement of the intrinsic parameters significantly.