On the detectability of ultralight scalar field dark matter with gravitational-wave detectors

Abstract

An ultralight scalar field is one of the dark matter candidates. If it couples with Standard Model particles, it oscillates mirrors in gravitational-wave detectors and generates detectable signals. We study the spectra of the signals taking into account the motion of the detectors due to the Earth's rotation/the detectors' orbital motion around the Sun and formulate a suitable data-analysis method to detect it. We find that our method can improve the existing constraints given by fifth-force experiments on one of the scalar field's coupling constants by a factor of $\sim 30$, $\sim 100$ and $\sim 350$ for $m_{\varphi }=2\times 10^{-17}\mathrm{eV},10^{-14}\mathrm{eV}$ and $10^{-12}\mathrm{eV}$ respectively, where $m_{\varphi }$ is the scalar field's mass. Our study demonstrates that experiments with gravitational-wave detectors play a complementary role to that Equivalence Principle tests do.

18 pages, 6 figures