Constraining the gravitational wave energy density of the Universe in the Range 0.1 Hz to 1 Hz using the Apollo Seismic Array

Understand

In this paper, we describe an analysis of Apollo era lunar seismic data that places an upper limit on an isotropic stochastic gravitational-wave background integrated over a year in the frequency range 0.1\,Hz -- 1\,Hz.

• We find that because the Moon's ambient noise background is much quieter than that of the Earth, significant improvements over an Earth based analysis were made.
• We find an upper limit of $\Omega_{\rm GW}<1.2\times 10^{5}$, which is three orders of magnitude smaller than a similar analysis of a global network of broadband seismometers on Earth and the best limits in this band to date.
• We also discuss the benefits of a potential Earth-Moon correlation search and compute the time-dependent overlap reduction function required for such an analysis.