Upper limits to surface force disturbances on LISA proof masses and the possibility of observing galactic binaries

TL;DR

This study measures parasitic surface force noise on a LISA proof mass replica, demonstrating the potential to detect galactic binary signals and discussing how upcoming tests will improve these limits.

Contribution

It provides the first measurement of surface force noise on a LISA-like proof mass in a realistic environment, informing future gravitational wave detection capabilities.

Findings

Measured upper limit for surface forces allows detection of galactic binaries with SNR up to 40.

Surface force noise measurement aligns with the design requirements for LISA.

Upcoming LISA Pathfinder tests will significantly improve noise limits.

Abstract

We report on the measurement of parasitic surface force noise on a hollow replica of a LISA (Laser Interferometer Space Antenna for the observation of gravitational waves) proof mass surrounded by a faithful representation of its in flight surroundings, namely the capacitive sensor used to detect proof-mass motion. Parasitic forces are detected through the corresponding torque exerted on the proof mass and measured with a torsion pendulum in the frequency range 0.1 30 mHz. The sensor electrodes, electrode housing and associated readout electronics have the same nominal design as for the flight hardware, including 4 mm gaps around the proof mass along the sensitive laser interferometry axis. We show that the measured upper limit for surface forces would allow detection of a number of galactic binaries signals with signal to noise ratio up to approximately 40 for 1 year integration. We also discuss how the flight test under development, LISA Pathfinder, will substantially improve this limit, approaching the performance required for LISA.