Tilt-To-Length Coupling in LISA -- Uncertainty and Biases

Fuente: arXiv
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Autori principali: Hartig, Marie-Sophie, Marmor, Joshua, George, Daniel, Paczkowski, Sarah, Sanjuan, Jose
Natura: Preprint
Pubblicazione: 2024
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author Hartig, Marie-Sophie
Marmor, Joshua
George, Daniel
Paczkowski, Sarah
Sanjuan, Jose
author_facet Hartig, Marie-Sophie
Marmor, Joshua
George, Daniel
Paczkowski, Sarah
Sanjuan, Jose
contents The coupling of the angular jitter of the spacecraft and their sub-assemblies with the optical bench and the telescope into the interferometric length readout will be a major noise source in the LISA mission. We refer to this noise as tilt-to-length (TTL) coupling. It will be reduced directly by realignments, and the residual noise will then be subtracted in post-processing. The success of these mitigation strategies depends on an accurate computation of the TTL coupling coefficients. We present here a thorough analysis of the accuracy of the coefficient estimation under different jitter characteristics, angular readout noise levels, and gravitational wave sources. We analyze in which cases the estimates degrade using two estimators, the common least squares estimator and the instrumental variables estimator. Our investigations show that angular readout noise leads to a systematic bias of the least squares estimator, depending on the TTL coupling coefficients, jitter and readout noise level, while the instrumental variable estimator converges to an unbiased result as the data set length increases. We present an equation that predicts the estimation bias of the least squares method due to angular readout noise.
format Preprint
id arxiv_https___arxiv_org_abs_2410_16475
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Tilt-To-Length Coupling in LISA -- Uncertainty and Biases
Hartig, Marie-Sophie
Marmor, Joshua
George, Daniel
Paczkowski, Sarah
Sanjuan, Jose
Instrumentation and Methods for Astrophysics
The coupling of the angular jitter of the spacecraft and their sub-assemblies with the optical bench and the telescope into the interferometric length readout will be a major noise source in the LISA mission. We refer to this noise as tilt-to-length (TTL) coupling. It will be reduced directly by realignments, and the residual noise will then be subtracted in post-processing. The success of these mitigation strategies depends on an accurate computation of the TTL coupling coefficients. We present here a thorough analysis of the accuracy of the coefficient estimation under different jitter characteristics, angular readout noise levels, and gravitational wave sources. We analyze in which cases the estimates degrade using two estimators, the common least squares estimator and the instrumental variables estimator. Our investigations show that angular readout noise leads to a systematic bias of the least squares estimator, depending on the TTL coupling coefficients, jitter and readout noise level, while the instrumental variable estimator converges to an unbiased result as the data set length increases. We present an equation that predicts the estimation bias of the least squares method due to angular readout noise.
title Tilt-To-Length Coupling in LISA -- Uncertainty and Biases
topic Instrumentation and Methods for Astrophysics
url https://arxiv.org/abs/2410.16475