Search for high-frequency gravitational waves via re-analysis of cavity axion data

TL;DR

This study reanalyzed cavity axion data to search for high-frequency gravitational waves, setting new upper limits and demonstrating the potential of resonant cavities as detectors for such signals.

Contribution

It presents the first search for high-frequency gravitational waves using cavity axion data, establishing new exclusion limits and highlighting the method's potential.

Findings

No candidates found in the 2 MHz frequency span.

Set 90% confidence-level exclusion limits on gravitational-wave strain.

Excluded black holes with specific masses within close proximity to Earth.

Abstract

Monochromatic high-frequency gravitational waves (HFGW) provide a distinctive probe of new physics scenarios, most notably axion clouds around rotating black holes formed via superradiance. We reanalyzed data from the CAPP-12T MC (multi-cell) axion haloscope experiment [Phys. Rev. Lett. 133,051802 (2024)]. The study covers a continuous $2\,$MHz frequency span centered at $5.311\,$GHz. No rescan candidates were found, and we set 90% confidence-level exclusion limits on the gravitational-wave strain, reaching $h_0 \approx 3.9 \times 10^{-21}$ in the most sensitive regions of the sky. Interpreted in the context of black-hole superradiance from axion clouds, the results exclude black holes with mass $M_{\mathrm{BH}} \simeq 1.22 \times 10^{-6}\,M_\odot$ within distances of $O(10^{-2})\,$AU from Earth, under benchmark assumptions. This work demonstrates the potential of electromagnetic resonant cavities as novel detectors of monochromatic HFGW and motivates future searches for both long-lived and transient signals.