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  • 1
    Language: English
    In: Physical review letters, 08 December 2017, Vol.119(23), pp.231101
    Description: According to the weak equivalence principle, all bodies should fall at the same rate in a gravitational field. The MICROSCOPE satellite, launched in April 2016, aims to test its validity at the 10^{-15} precision level, by measuring the force required to maintain two test masses (of titanium and platinum alloys) exactly in the same orbit. A nonvanishing result would correspond to a violation of the equivalence principle, or to the discovery of a new long-range force. Analysis of the first data gives δ(Ti,Pt)=[-1±9(stat)±9(syst)]×10^{-15} (1σ statistical uncertainty) for the titanium-platinum Eötvös parameter characterizing the relative difference in their free-fall accelerations.
    Keywords: Astrophysics - Instrumentation And Methods For Astrophysics ; Astrophysics - Cosmology And Nongalactic Astrophysics ; General Relativity And Quantum Cosmology;
    ISSN: 00319007
    E-ISSN: 1079-7114
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  • 2
    In: Proceedings of the International Astronomical Union, 2014, Vol.10(S306), pp.382-384
    Description: Abstract Theories beyond the Standard Model and General Relativity predict a violation of the Weak Equivalence Principle (WEP) just below the current best experimental upper limits. MICROSCOPE (Micro-Satellite à traînée Compensée pour l'Observation du Principe d'Equivalence) will allow us to lower them by two orders of magnitude, and maybe to detect a WEP violation. However, analyzing the MICROSCOPE data will be challenging, mostly because of missing data and a colored noise burrying the signal of interest. In this communication, we apply an inpainting technique to simulated MICROSCOPE data and show that inpainting will help detect a WEP violation signal.
    Keywords: Contributed Papers; Gravitation; Methods: Data Analysis; Methods: Statistical
    ISSN: 1743-9213
    E-ISSN: 1743-9221
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  • 3
    Language: English
    Description: The Equivalence Principle (EP) is a cornerstone of General Relativity, and is called into question by the attempts to build more comprehensive theories in fundamental physics such as string theories. The MICROSCOPE space mission aims at testing this principle through the universality of...
    Keywords: Sciences of the Universe ; Astrophysics ; Experimental Test of Gravitational Theories ; Spaceborne Instruments ; Data Processing ; Spectral Analysis ; Missing Data ; Physique Gravitationnelle Expérimentale ; Instrumentation Spatiale ; Traitement de Données ; Analyse Spectrale ; Données Manquantes
    Source: Hyper Article en Ligne (CCSd)
    Source: Hyper Article en Ligne Open Access (CCSd)
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  • 4
    Language: English
    In: Physical Review D, 12/2015, Vol.92(11)
    Description: Missing data are a common problem in experimental and observational physics. They can be caused by various sources, either an instrument's saturation, or a contamination from an external event, or a data loss. In particular, they can have a disastrous effect when one is seeking to characterize a colored-noise-dominated signal in Fourier space, since they create a spectral leakage that can artificially increase the noise. It is therefore important to either take them into account or to correct for them prior to e.g. a Least-Square fit of the signal to be characterized. In this paper, we present an application of the {\it inpainting} algorithm to mock MICROSCOPE data; {\it inpainting} is based on a sparsity assumption, and has already been used in various astrophysical contexts; MICROSCOPE is a French Space Agency mission, whose launch is expected in 2016, that aims to test the Weak Equivalence Principle down to the $10^{-15}$ level. We then explore the {\it inpainting} dependence on the number of gaps and the total fraction of missing values. We show that, in a worst-case scenario, after reconstructing missing values with {\it inpainting}, a Least-Square fit may allow us to significantly measure a $1.1\times10^{-15}$ Equivalence Principle violation signal, which is sufficiently close to the MICROSCOPE requirements to implement {\it inpainting} in the official MICROSCOPE data processing and analysis pipeline. Together with the previously published KARMA method, {\it inpainting} will then allow us to independently characterize and cross-check an Equivalence Principle violation signal detection down to the $10^{-15}$ level. Comment: Accepted for publication in Physical Review D. 12 pages, 6 figures
    Keywords: Astrophysics - Instrumentation And Methods For Astrophysics ; General Relativity And Quantum Cosmology;
    ISSN: 1550-7998
    E-ISSN: 1550-2368
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  • 5
    Language: English
    In: Physical Review D, 27 December 2016, Vol.94(123015)
    Description: The MICROSCOPE space mission, launched on April 25, 2016, aims to test the weak equivalence principle (WEP) with a 10^−15 precision. Reaching this performance requires an accurate and robust data analysis method, especially since the possible WEP violation signal will be dominated by a...
    Keywords: Physics ; Physics ; Instrumentation and Detectors ; Analyse Donnees ; Microscope ; Physics
    ISSN: 1550-7998
    ISSN: 24700010
    E-ISSN: 1550-2368
    E-ISSN: 24700029
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  • 6
    Language: English
    In: Physical Review D, March 2015, Vol.91(6)
    Description: The analysis of physical measurements often copes with highly correlated noises and interruptions caused by outliers, saturation events or transmission losses. We assess the impact of missing data on the performance of linear regression analysis involving the fit of modeled or measured time series. We show that data gaps can significantly alter the precision of the regression parameter estimation in the presence of colored noise, due to the frequency leakage of the noise power. We present a regression method which cancels this effect and estimates the parameters of interest with a precision comparable to the complete data case, even if the noise power spectral density (PSD) is not known a priori. The method is based on an autoregressive (AR) fit of the noise, which allows us to build an approximate generalized least squares estimator approaching the minimal variance bound. The method, which can be applied to any similar data processing, is tested on simulated measurements of the MICROSCOPE space mission, whose goal is to test the Weak Equivalence Principle (WEP) with a precision of $10^{-15}$. In this particular context the signal of interest is the WEP violation signal expected to be found around a well defined frequency. We test our method with different gap patterns and noise of known PSD and find that the results agree with the mission requirements, decreasing the uncertainty by a factor 60 with respect to ordinary least squares methods. We show that it also provides a test of significance to assess the uncertainty of the measurement. Comment: 12 pages, 4 figures, to be published in Phys. Rev. D
    Keywords: Physics ; Astrophysics ; Physics ; General Relativity and Quantum Cosmology ; Physics
    ISSN: 1550-7998
    E-ISSN: 1550-2368
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  • 7
    Language: English
    In: Physical Review D, 6/2016, Vol.93(12)
    Description: We present a Gaussian regression method for time series with missing data and stationary residuals of unknown power spectral density (PSD). The missing data are efficiently estimated by their conditional expectation as in universal Kriging, based on the circulant approximation of the complete data covariance. After initialization with an autoregessive fit of the noise, a few iterations of estimation/reconstruction steps are performed until convergence of the regression and PSD estimates, in a way similar to the expectation-conditional-maximization algorithm. The estimation can be performed for an arbitrary PSD provided that it is sufficiently smooth. The algorithm is developed in the framework of the MICROSCOPE space mission whose goal is to test the weak equivalence principle (WEP) with a precision of $10^{-15}$. We show by numerical simulations that the developed method allows us to meet three major requirements: to maintain the targeted precision of the WEP test in spite of the loss of data, to calculate a reliable estimate of this precision and of the noise level, and finally to provide consistent and faithful reconstructed data to the scientific community. Baghi, Quentin; Métris, Gilles; Bergé, Joël; Christophe, Bruno; Touboul, Pierre; Rodrigues, Manuel
    Keywords: Physics;
    ISSN: 2470-0010
    E-ISSN: 2470-0029
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  • 8
    Language: English
    In: 14th Marcel Grossmann Meeting on Recent Developments in Theoretical and Experimental General Relativity, Astrophysics, and Relativistic Field Theories, 2017, Vol.4, pp.3586-3590
    Description: The aim of the MICROSCOPE space mission is to test the weak equivalence principle (WEP) with a precision of 10−15, 100 times better than on-ground experiments. The WEP violation signal that we look for in flight has a particular frequency...
    Keywords: Physics ; General Relativity and Quantum Cosmology ; Data Processing ; Physics
    Source: Hyper Article en Ligne (CCSd)
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  • 9
    Language: English
    In: Mon.Not.Roy.Astron.Soc, 2019, Vol.486(1), pp.544-559
    Description: We introduce one- and two-dimensional ‘exponential shapelets’: orthonormal basis functions that efficiently model isolated features in data. They are built from eigenfunctions of the quantum mechanical hydrogen atom, and inherit mathematics with elegant properties under Fourier transform,...
    Keywords: Physics ; Physics ; Instrumentation and Detectors ; Physics ; General Relativity and Quantum Cosmology ; Methods: Data Analysis ; Physics
    ISSN: 00358711
    E-ISSN: 13652966
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  • 10
    Description: We introduce one- and two-dimensional `exponential shapelets': orthonormal basis functions that efficiently model isolated features in data. They are built from eigenfunctions of the quantum mechanical hydrogen atom, and inherit mathematics with elegant properties under Fourier transform, and hence (de)convolution. For a wide variety of data, exponential shapelets compress information better than Gauss-Hermite/Gauss-Laguerre (`shapelet') decomposition, and generalise previous attempts that were limited to 1D or circularly symmetric basis functions. We discuss example applications in astronomy, fundamental physics and space geodesy. Comment: Accepted for publication in MNRAS. 13+4 pages
    Keywords: Astrophysics - Instrumentation And Methods For Astrophysics ; General Relativity And Quantum Cosmology
    Source: Cornell University
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