Precision measurements of the magnetic parameters of LISA Pathfinder test masses

TL;DR

This paper reports precise magnetic parameter measurements of LISA Pathfinder test masses, crucial for understanding magnetic influences on gravitational wave detection sensitivity in space.

Contribution

It provides high-precision in-flight magnetic parameter estimates, improving understanding of magnetic effects on space-based gravitational wave observatories.

Findings

Remanent magnetic moment: (0.245±0.081) nAm²

Background magnetic field: (414±74) nT

Magnetic susceptibility: (-3.35±0.15)×10⁻⁵

Abstract

A precise characterization of the magnetic properties of LISA Pathfinder free falling test-masses is of special interest for future gravitational wave observatory in space. Magnetic forces have an important impact on the instrument sensitivity in the low frequency regime below the millihertz. In this paper we report on the magnetic injection experiments performed throughout LISA Pathfinder operations. We show how these experiments allowed a high precision estimate of the instrument magnetic parameters. The remanent magnetic moment was found to have a modulus of $(0.245\pm0.081)\,\rm{nAm}^2$, the x-component of the background magnetic field within the test masses position was measured to be $(414 \pm 74)$ nT and its gradient had a value of $(-7.4\pm 2.1)\,\mu$T/m. Finally, we also measured the test mass magnetic susceptibility to be $(-3.35\pm0.15)\times$10$^{-5}$ in the low frequency regime. All results are in agreement with on-ground estimates.