Exploring spin of ultralight dark matter with gravitational wave detectors

TL;DR

This paper introduces a new method using gravitational wave detectors to identify the spin of ultralight dark matter, revealing distinctive signatures for different spins and highlighting the importance of finite-time effects.

Contribution

It presents a novel approach to distinguish ULDM spin via interferometric signals and analyzes the impact of finite-time light-travel effects on current constraints.

Findings

Finite-time traveling effect dominates for spin-0 and spin-1 ULDM signals.

Overlap reduction functions enable spin differentiation between ULDM types.

Current constraints on spin-1 ULDM coupling weaken by 30 times when considering finite-time effects.

Abstract

We propose a novel method for distinguishing the spin of ultralight dark matter (ULDM) using interferometric gravitational wave detectors. ULDM can be a bosonic field of spin-0, 1, or 2, and each induces distinctive signatures in signals. We find that the finite-time traveling effect causes a dominant signal for spin-0 and spin-1 ULDM, while not for spin-2. By using overlap reduction functions (ORF) of multiple detectors, we can differentiate between the spins of ULDM. Furthermore, we point out that the current constraint on the coupling constant of spin-1 ULDM to baryons becomes 30 times weaker when the finite-time light-travel effect on the ORF is taken into account.