High-Frequency Gravitational Wave Search with ABRACADABRA-10\,cm

Abstract

High-frequency gravitational waves (HFGWs), above 10 kHz, promise a clean probe of new physics, largely free of the astrophysical backgrounds that complicate lower-frequency searches. Axion detectors, which search for axion dark matter via its coupling to electrodynamics in a strong magnetic field, should also be sensitive to HFGWs. We present the first dedicated search for HFGWs, using a modified ABRA-10cm axion detector, ABRA-GW, that runs simultaneously with a conventional axion search. ABRA-GW opens the 10 kHz-5 MHz band to HFGW searches and performs the first transient search by an axion experiment, targeting primordial black hole (PBH) mergers. Axion sensitivity is unaffected by the added gravitational-wave channel, and HFGW sensitivity matches theoretical expectations. This work demonstrates the broad physics reach of axion detectors and represents a first step toward a potential HFGW discovery.

Comments: In this version of the paper, the framing has been updated and the presentation of data improved for publication