Searching for Dark Photon Dark Matter with Gravitational-Wave Detectors

If dark matter stems from the background of a very light gauge boson, this gauge boson could exert forces on test masses in gravitational wave detectors, resulting in displacements with a characteristic frequency set by the gauge boson mass. We outline a novel search strategy for such dark matter, assuming the dark photon is the gauge boson of $U(1{)}_B$ or $U(1{)}_{B-L}$. We show that both ground-based and future space-based gravitational wave detectors have the capability to make a $5\sigma$ discovery in unexplored parameter regimes.

Figure 1

The $2\sigma$ exclusion limit and $5\sigma$ discovery potential obtained from LIGO and LISA after 2 yr of coincident running for $B$ (upper) and ($B-L$) (lower) dark photon dark matter. Coupling strength is normalized to EM coupling strength, i.e., ${\epsilon }^2=\alpha /{\alpha }_{\mathrm{EM}}$, which is not constrained theoretically. The blue and green curves are limits from the Eöt-Wash (EW) experiment [11, 12] and the Lunar Laser Ranging (LLR) experiment [13, 14, 15]. The idealized design LIGO sensitivity curves used here do not include very narrow bands of instrumental line artifacts, such as from 60-Hz power mains contamination and vibration modes of mirror suspension fibers, for which DPDM sensitivity is degraded [42, 43].