We’re Going to Steal the Moon (For Gravitational Waves)
Abstract
- Gravitational Waves have been detected via LIGO as well as with pulsar timing arrays, which use detection’s high frequency(~100 hz range) and low freq (nano-hertz).
- These leaves a gap between ~.001-.1 Hz which includes SMBH progenitors
- Space observatories such as LISA have been proposed to fill this gap, however, this paper proposes uses the moon as an Antenna instead
- The moon could theoretically serve as a large detector, as GWs passing through would make it vibrate (or “ring”) slightly. This could be detected easier then on earth, due to less background noise
- Authors seek to model and simulate this behavior
Modeling
- Spectral Element Method (SEM): High resolution numerical simulations that calculate how seismic waves propagate and interfere within the Moon when hit by GWs
- Normal-mode Perturbation Method: Analytical method that provides the mathematical framework for describing the Moon’s vibrations
These models serve to, in great detail, model how the inside of the moon would react and behave due to passing GWs
Results
Authors found that thicker regions of the moons crust served to amplify the strength of passing GWs.
They initially took a spherical cow approach to modeling, where they assumed that the surface of the moon was spherically symmetric, which allowed it be modeled using normal modes. When they mixed in the variations in crust thickness, the patterns began to mix together, making some patterns work constructively and other destructively.
Perturbation theory is used to predict these patterns.
This paper thus proposes the methodology which could be used for using the moon as a GW detector, laying the framework in-case it becomes a real predictor.