Gravitational Interaction of Ultralight Dark Matter with Interferometers

TL;DR

This paper explores how ultralight dark matter's gravitational effects could produce detectable signals in long-baseline gravitational wave interferometers, potentially allowing constraints on dark matter density at solar system scales.

Contribution

It provides a systematic calculation of the ultralight dark matter power spectrum in interferometers and assesses their sensitivity to dark matter density.

Findings

Long-baseline interferometers are most sensitive to ultralight dark matter effects.

Current detectors like LISA are only marginally affected by ultralight dark matter.

Future AU-scale interferometers could probe dark matter densities hundreds of times higher than local measurements.

Abstract

Ultralight dark matter exhibits an order-one density fluctuation over the spatial scale of its wavelength. These fluctuations gravitationally interact with gravitational wave interferometers, leading to distinctive signals in detectors. We investigate the ultralight dark matter-induced effects in the gravitational wave interferometers. We perform a systematic computation of the power spectrum of ultralight dark matter in interferometers. We show that the ultralight dark matter-induced effect is most relevant for the interferometers with long baseline and that it is only a sub-leading effect compared to the estimated noise level in the case of Laser Interferometer Space Antenna or future interferometers with an arm-length comparable to a few astronomical units. Gravitational wave interferometers can then place upper limits on the ultralight dark matter density in the solar system. We find that, under certain assumptions, future interferometers with AU-scale arm-length might probe the dark matter density a few hundred times the local dark matter density, which is measured over a much larger spatial scale.