Mapping Anisotropies in the Stochastic Gravitational-Wave Background with space detector networks

TL;DR

This paper develops a data analysis pipeline for space-based gravitational-wave detectors to map and localize anisotropies in the stochastic gravitational-wave background, enhancing understanding of cosmic sources.

Contribution

It introduces the first dedicated pipeline for joint analysis of TianQin, LISA, and Taiji detectors to reconstruct the SGWB's spatial distribution.

Findings

Reconstruction of the angular power spectrum up to l=14.

Effective mapping of anisotropies considering detector noise.

Potential insights into galactic binaries and early Universe imprints.

Abstract

Future space-based gravitational-wave detectors such as TianQin, LISA, and Taiji are expected to conduct joint observations. Such a multi-detector network will provide complementary viewing angles for the anisotropic stochastic gravitational-wave background (SGWB), thereby significantly enhancing the capability to reconstruct and localize its spatial distribution. In this paper, we have established the first dedicated data analysis pipeline for the anisotropic stochastic gravitational-wave background using a joint network of TianQin, LISA, and Taiji. Our analysis incorporates both Gaussian, stationary, and unpolarized point sources from diverse sky locations as well as a random sky map. We have performed full-sky map reconstruction in pixel space using maximum likelihood estimation to extract the angular distribution of the SGWB. The results demonstrate that, when considering the detector noise, the TianQin+LISA+Taiji detector network can reconstruct the angular power spectrum of the stochastic background up to a maximum multipole moment of $l = 14 $, which can provide valuable information for studies on the spatial distribution of galactic compact binaries and physical imprints from the early Universe.