# Estimating the angular power spectrum of the gravitational-wave background in the presence of shot noise

## TL;DR

This paper introduces a new method to accurately estimate the angular power spectrum of the gravitational-wave background's anisotropies, effectively removing shot noise bias by combining independent data segments, thus enabling better insights into large-scale structure.

## Contribution

A novel estimator for the gravitational-wave background anisotropy spectrum that is unbiased and efficient in the presence of shot noise, using combined independent data segments.

## Key findings

- The estimator removes shot noise bias from the spectrum.
- It is unbiased and achieves minimum variance with many data segments.
- The method enhances the extraction of astrophysical information from GW data.

## Abstract

There has been much recent interest in studying anisotropies in the astrophysical gravitational-wave (GW) background, as these could provide us with interesting new information about galaxy clustering and large-scale structure. However, this information is obscured by shot noise, caused by the finite number of GW sources that contribute to the background at any given time. We develop a new method for estimating the angular spectrum of anisotropies, based on the principle of combining statistically-independent data segments. We show that this gives an unbiased estimate of the true, astrophysical spectrum, removing the offset due to shot noise power, and that in the limit of many data segments, it is the most efficient (i.e. lowest-variance) estimator possible.