Newtonian noise, also known as gravity gradient noise arises when local perturbations in density cause fluctuations in gravitational field influencing nearby masses. These fluctuations are predicted to act as a limit at lower frequencies for the sensitivity of terrestrial based gravitational wave detected beyond the next generation of detectors. As such the need to directly measure and then negate Newtonian noise is of ongoing interest to the field of gravitational wave astronomy.
To this end the ANU centre for gravitational physics is developing a direct Newtonian noise sensor called the TorPeDO (Torsion Pendulum Dual Oscillator). Based on two bar-like torsion pendula the TorPeDO system has a highly sensitive differential yaw mode capable of detecting the local gravitational fluctuations that make up Newtonian Noise. In this talk I will explore the mechanical coupling into the differential yaw mode from external factors and how we propose to minimise this coupling to reach our design sensitivity.