Searching for Dark Clumps with Gravitational-Wave Detectors

Sebastian Baum, Michael A. Fedderke, Peter W. Graham

Submitted on 29 June 2022


Dark compact objects ("clumps") transiting the Solar System exert accelerations on the test masses (TM) in a gravitational-wave (GW) detector. We reexamine the detectability of these clump transits in a variety of current and future GW detectors, operating over a broad range of frequencies. TM accelerations induced by clump transits through the inner Solar System have frequency content around fμHz. Some of us [arXiv:2112.11431] recently proposed a GW detection concept with μHz sensitivity, based on asteroid-to-asteroid ranging. From the detailed sensitivity projection for this concept, we find both analytically and in simulation that purely gravitational clump-matter interactions would yield one detectable transit every 20 yrs, if clumps with mass mcl1014kg saturate the dark-matter (DM) density. Other (proposed) GW detectors using local TMs and operating in higher frequency bands, are sensitive to smaller clump masses and have smaller rates of discoverable signals. We also consider the case of clumps endowed with an additional long-range clump-matter fifth force significantly stronger than gravity (but evading known fifth-force constraints). For the μHz detector concept, we use simulations to show that, for example, a clump-matter fifth-force 103 times stronger than gravity with a range of AU would boost the rate of detectable transits to a few per year for clumps in the mass range 1011kgmcl1014kg, even if they are a 1% sub-component of the DM. The ability of μHz GW detectors to probe asteroid-mass-scale dark objects that may otherwise be undetectable bolsters the science case for their development.


Comment: 21 pages, 4 figures

Subjects: Astrophysics - Cosmology and Nongalactic Astrophysics; General Relativity and Quantum Cosmology; High Energy Physics - Phenomenology