Speaker
Description
There is a recent growing interest in detecting gravitational waves (GWs) via lunar seismic measurements. It requires a precise understanding of the Moon’s response to passing GWs but previous studies derived two seemingly different response functions—one using a field-theory approach and the other based on tidal forces—raising questions about their equivalence. Here, we analytically and numerically model the normal modes of the Moon excited by GWs. We demonstrate that the aforementioned functions are identical, with differences arising only from coordinate choices. Using the correct response function, we reassess the sensitivity of proposed lunar seismometers (e.g., China’s Chang’e and Europe’s Lunar GW Antenna), revealing flatter sensitivity curves between 10⁻³–0.1 Hz than predicted by previous models. Equipped with the better understanding of the lunar response to GWs, we reevaluate the feasibility of constraining the stochastic GW background with lunar seismometer networks, deriving updated pattern and overlap reduction functions while relaxing idealized instrument assumptions.
