Improved sensitivity of interferometric gravitational wave detectors to ultralight vector dark matter from the finite light-traveling time

TL;DR

This paper demonstrates that accounting for finite light-travel time in gravitational wave detectors significantly enhances their sensitivity to ultralight vector dark matter, leading to improved constraints on dark matter couplings.

Contribution

It introduces a new effect of finite light-travel time that substantially boosts the sensitivity of gravitational wave detectors to vector dark matter.

Findings

Advanced LIGO constraints improved by an order of magnitude.

Future detectors' sensitivities are greatly enhanced.

Maximum improvement factors range from 140 to 1800 depending on the detector.

Abstract

Recently several studies have pointed out that gravitational-wave detectors are sensitive to ultralight vector dark matter and can improve the current best constraints given by the Equivalence Principle tests. While a gravitational-wave detector is a highly precise measuring tool of the length difference of its arms, its sensitivity is limited because the displacements of its test mass mirrors caused by vector dark matter are almost common. In this Letter we point out that the sensitivity is significantly improved if the effect of finite light-traveling time in the detector's arms is taken into account. This effect enables advanced LIGO to improve the constraints on the $U(1)_{B-L}$ gauge coupling by an order of magnitude compared with the current best constraints. It also makes the sensitivities of the future gravitational-wave detectors overwhelmingly better than the current ones. The factor by which the constraints are improved due to the new effect depends on the mass of the vector dark matter, and the maximum improvement factors are $470$, $880$, $1600$, $180$ and $1400$ for advanced LIGO, Einstein Telescope, Cosmic Explorer, DECIGO and LISA respectively. Including the new effect, we update the constraints given by the first observing run of advanced LIGO and improve the constraints on the $U(1)_B$ gauge coupling by an order of magnitude compared with the current best constraints.