Measuring the dipole component of possible Galaxy-binary alignment in the mHz band

TL;DR

This paper explores how the LISA gravitational wave detector can measure the dipole distribution of white dwarf binaries in the Galactic bulge, considering sky thickness and extending to extragalactic sources with BBO/DECIGO.

Contribution

It introduces a new formulation leveraging parity properties to assess the dipole pattern measurement feasibility with LISA.

Findings

Sky thickness affects dipole measurement accuracy.

LISA can potentially detect the dipole pattern in the Galactic bulge.

Extensions to BBO/DECIGO for extragalactic binaries are discussed.

Abstract

We discuss the usability of the gravitational wave detector LISA for studying the orientational distribution of compact white dwarf binaries in the Galactic bulge. We pay special attention to measuring the dipole pattern of the distribution around the Galactic rotation axis. Based on our new formulation, which leverages the parity properties of the involved systems, we found that the apparent thickness of the bulge in the sky becomes critical for the dipole measurement. We also discuss the extra-Galactic studies for black hole binaries and neutron star binaries with BBO/DECIGO.