Tilt-to-length coupling in LISA Pathfinder

Analytical modeling

authored by: Marie Sophie Hartig, Gudrun Wanner
Abstract: Tilt-to-length coupling was the limiting noise source in LISA Pathfinder between 20 and 200 mHz before subtraction in postprocessing. To prevent the adding of sensing noise to the data by the subtraction process, the success of this strategy depended on a previous direct noise reduction by test mass alignment. The exact dependency of the level of tilt-to-length coupling on the set points of LISA Pathfinder's test masses was not understood until the end of the mission. Here, we present, for the first time, an analytical tilt-to-length coupling model that describes the coupling noise changes due to the realignments. We report on the different mechanisms, namely the lever arm and piston effect as well as the coupling due to transmissive components, and how they contribute to the full coupling. Further, we show that a pure geometric model would not have been sufficient to describe the coupling in LISA Pathfinder. Therefore, we model also the nongeometric tilt-to-length noise contributions. For the resulting coupling coefficients of the full model, we compute the expected error bars based on the known individual error sources. Also, we validated the analytical model against numerical simulations. A detailed study and thorough understanding of this noise are the basis for a successful analysis of the LISA Pathfinder data with respect to tilt-to-length coupling.
Organisation(s): Institute of Gravitation Physics
External Organisation(s): Max Planck Institute for Gravitational Physics (Albert Einstein Institute)
Type: Article
Journal: Physical Review D
Volume: 108
ISSN: 2470-0010
Publication date: 26.07.2023
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Nuclear and High Energy Physics
Electronic version(s): https://doi.org/10.48550/arXiv.2305.03667 (Access: Open)
https://doi.org/10.1103/PhysRevD.108.022008 (Access: Open)

BibTeX

@article{fca6aba80866439fb2de305010d7b07a,
title = "Tilt-to-length coupling in LISA Pathfinder: Analytical modeling",
abstract = "Tilt-to-length coupling was the limiting noise source in LISA Pathfinder between 20 and 200 mHz before subtraction in postprocessing. To prevent the adding of sensing noise to the data by the subtraction process, the success of this strategy depended on a previous direct noise reduction by test mass alignment. The exact dependency of the level of tilt-to-length coupling on the set points of LISA Pathfinder's test masses was not understood until the end of the mission. Here, we present, for the first time, an analytical tilt-to-length coupling model that describes the coupling noise changes due to the realignments. We report on the different mechanisms, namely the lever arm and piston effect as well as the coupling due to transmissive components, and how they contribute to the full coupling. Further, we show that a pure geometric model would not have been sufficient to describe the coupling in LISA Pathfinder. Therefore, we model also the nongeometric tilt-to-length noise contributions. For the resulting coupling coefficients of the full model, we compute the expected error bars based on the known individual error sources. Also, we validated the analytical model against numerical simulations. A detailed study and thorough understanding of this noise are the basis for a successful analysis of the LISA Pathfinder data with respect to tilt-to-length coupling.",
author = "Hartig, {Marie Sophie} and Gudrun Wanner",
note = "Funding Information: We thank Valerio Ferroni and Nikolaos Karnesis for valuable discussions. This work was made possible by funds of both the German Space Agency, DLR, and the Deutsche Forschungsgemeinschaft (DFG). We gratefully acknowledge the German Space Agency, DLR and support by the Federal Ministry for Economic Affairs and Climate Action based on a resolution of the German Bundestag (Grants No. FKZ 50OQ0501, No. FKZ 50OQ1601, and No. FKZ 50OQ1801). Likewise, we gratefully acknowledge the Deutsche Forschungsgemeinschaft (DFG) for funding the Cluster of Excellence QuantumFrontiers (Grant No. EXC 2123, Project ID 390837967). ",
year = "2023",
month = jul,
day = "26",
doi = "10.48550/arXiv.2305.03667",
language = "English",
volume = "108",
journal = "Physical Review D",
issn = "2470-0010",
publisher = "American Institute of Physics",
number = "2",
}