Constraining gravitational-wave polarizations with Taiji

TL;DR

This paper investigates Taiji's potential to detect various gravitational-wave polarization modes, demonstrating high measurement accuracy for different modes in the context of massive black hole binaries at redshift 1.

Contribution

It is the first study to evaluate Taiji's ability to constrain multiple gravitational-wave polarization modes within the parametrized post-Einsteinian framework.

Findings

Taiji can measure dipole and quadrupole emission with ~0.04% accuracy.

Scalar transverse and longitudinal modes can be measured up to ~0.01.

Vector modes can be constrained up to ~0.0005.

Abstract

Space-based gravitational-wave detectors consist of a triangle of three spacecraft, which makes it possible to detect polarization modes of gravitational waves due to the motion of the detectors in space. In this paper we explore the ability of Taiji to detect the polarization modes in the parametrized post-Einsteinian framework. Assuming massive black hole binaries with the total mass of $M=4\times10^5\,M_{\odot}$ at redshift of $z=1$, we find that Taiji can measure the dipole and quadruple emission ($\Delta\alpha_D/\alpha_D$ and $\Delta\alpha_Q/\alpha_Q$) with the accuracy of up to $\sim 0.04\%$, with the fiducial value of $\alpha_D=0.001$, the scalar transverse and longitudinal modes ($\Delta\alpha_B$ and $\Delta\alpha_L$) up to $\sim 0.01$, and the vector modes ($\Delta\alpha_V$) up to $\sim 0.0005$.