84846704
LISA Pathfinder
M Armanoa, H Audleyb, J Bairdc, P Binetruy d,∗, M Bornb, D Bortoluzzie, E Castellif , A Cavallerif , A Cesarinig , A M Cruiseh, K Danzmannb, M de Deus Silvaa, I Diepholzb, G Dixonh, R Dolesif , L Ferraiolii, V Ferronif , E D Fitzsimonsj , M Freschia, L Gesak, F Gibertf , D Giardinii, R Giusterif , C Grimanig , J Grzymischl, I Harrisonm, G Heinzelb, M Hewitsonb, D Hollingtonc, D Hoylandh, M Huellerf , H Inchauspéd, O Jennrichl, P Jetzern, N Karnesisb, B Kauneb, N Korsakovao, C J Killowo, J A Lobok,†, I Llorok, L Liuf , J P López-Zaragozak, R Maarschalkerweerdm, D Mancei N Meshskari, V Mart́ınk, L Martin-Poloa, J Martinod, F Martin-Porquerasa, I Mateosk, P W McNamaral, J Mendesm, L Mendesa, M Nofrariask, S Paczkowskib?, M Perreur-Lloydo, A Petiteaud, P Pivatof , E Plagnold, J Ramos-Castrop, J Reicheb, D I Robertsono, F Rivask, G Russanof , J Slutskyq , C F Sopuertak, T Sumnerc, D Texiera, J I Thorpeq , D Vetrugnof , S Vitalef , G Wannerb, H Wardo, P Wassc,r, W J Weberf , L Wisselb, A Wittchenb, and P Zweifeli a European Space Astronomy Centre, European Space Agency, Villanueva de la Cañada, 28692 Madrid, Spain
63844509
The LISA Pathfinder interferometry-hardware and system testing
Preparations for the LISA Pathfinder mission have reached an exciting stage. Tests of the engineering model (EM) of the optical metrology system have recently been completed at the Albert Einstein Institute, Hannover, and flight model tests are now underway. Significantly, they represent the first complete integration and testing of the space-qualified hardware and are the first tests on an optical system level. The results and test procedures of these campaigns will be utilized directly in the ground-based flight hardware tests, and subsequently during in-flight operations. In addition, they allow valuable testing of the data analysis methods using the MATLAB-based LTP data analysis toolbox. This paper presents an overview of the results from the EM test campaign that was successfully completed in December 2009.
120641812
Progress in the development of a position sensor for LISA drag-free control
We report on progress in the development of free-falling moving test-masses for LISA and for the related technology demonstration mission. We present simple formulae to evaluate the performance of the device as a function of the various design parameters, and we compare them with preliminary experimental results from a test prototype we are developing. Quantitative agreement is found. Finally, we present a control law, along with a performance simulation, for low-frequency electrostatic suspension of the test-mass with minimal perturbation of the motion within the measuring frequency band.
55218371
Brownian force noise from molecular collisions and the sensitivity of advanced gravitational wave observatories
We present an analysis of Brownian force noise from residual gas damping of reference test masses as a fundamental sensitivity limit in small force experiments. The resulting acceleration noise increases significantly when the distance of the test mass to the surrounding experimental apparatus is smaller than the dimension of the test mass itself. For the Advanced LIGO interferometric gravitational wave observatory, where the relevant test mass is a suspended 340 mm diameter cylindrical end mirror, the force noise power is increased by roughly a factor 40 by the presence of a similarly shaped reaction mass at a nominal separation of 5 mm. The force noise, of order 20 fN\rthz\ for $2 \times 10^{-6}$ Pa of residual H$_2$ gas, rivals quantum optical fluctuations as the dominant noise source between 10 and 30 Hz. We present here a numerical and analytical analysis for the gas damping force noise for Advanced LIGO, backed up by experimental evidence from several recent measurements. Finally, we discuss the impact of residual gas damping on the gravitational wave sensitivity and possible mitigation strategies.
117102512
Towards an Ultracryogenic Bar Observatory for Gravitational Wave Bursts
36133266
From laboratory experiments to LISA Pathfinder: achieving LISA geodesic motion
This paper presents a quantitative assessment of the performance of the upcoming LISA Pathfinder geodesic explorer mission. The findings are based on the results of extensive ground testing and simulation campaigns using flight hardware, flight control and operations algorithms. The results show that, for the central experiment of measuring the stray differential acceleration between the LISA test masses, LISA Pathfinder will be able to verify the overall acceleration noise to within a factor 2 of the LISA requirement at 1 mHz and within a factor 6 at 0.1 mHz. We also discuss the key elements of the physical model of disturbances, coming from LISA Pathfinder and ground measurement that will guarantee the LISA performance.
17415632
Approximate solutions in General Relativity via deformation of embeddings
A systematic study of deformations of four-dimensional Einsteinian space-times embedded in a pseudo-Euclidean space E N of higher dimension is presented. Infinitesimal deformations, seen as vector fields in E N , can be divided in two parts, tangent to the embedded hypersurface and orthogonal to it; only the second ones are relevant, the tangent ones being equivalent to coordinate transformations in the embedded manifold. The geometrical quantities can be then expressed in terms of embedding functions z A and their infinitesimal deformations v A z A → ˜ z A = z A + e v A . The deformations are called Einsteinian if they keep Einstein equations satisfied up to a given order in e. The system so obtained is then analyzed in particular in the case of the Schwarzschild metric taken as the starting point, and some solutions of the first-order deformation of Einstein’s equations are found. We discuss also second and third order deformations leading to wave-like solutions and to the departure from spherical symmetry towards an axial one (the approximate Kerr solution) 1
118465419
Parameter estimation from gravitational waves generated by nonspinning binary black holes with laser interferometers: Beyond the Fisher information
In this paper we apply to gravitational waves from nonspinning binary systems a recently introduced frequentist methodology to calculate analytically the error for a maximum likelihood estimate of physical parameters. While existing literature focuses on using the Cramer Rao Lower bound and Monte Carlo simulations, we use a power expansion of the bias and covariance in inverse powers of the signal to noise ratio. The use of higher order derivatives of the likelihood function in the expansions makes the prediction also sensitive to the secondary lobes of the maximum likelihood estimate probability distribution. We discuss conditions for validity of the Cramer Rao Lower bound and predict new features in regions of the parameter space currently not explored. For example, we see how the bias can become the most important contributor to the parameters' errors for high mass systems (200M(circle dot) and above).
9403518
Measuring the spin of black holes in binary systems using gravitational waves.
Compact binary coalescences are the most promising sources of gravitational waves (GWs) for ground-based detectors. Binary systems containing one or two spinning black holes are particularly interesting due to spin-orbit (and eventual spin-spin) interactions and the opportunity of measuring spins directly through GW observations. In this Letter, we analyze simulated signals emitted by spinning binaries with several values of masses, spins, orientations, and signal-to-noise ratios, as detected by an advanced LIGO-Virgo network. We find that for moderate or high signal-to-noise ratio the spin magnitudes can be estimated with errors of a few percent (5%-30%) for neutron star-black hole (black hole-black hole) systems. Spins' tilt angle can be estimated with errors of 0.04 rad in the best cases, but typical values will be above 0.1 rad. Errors will be larger for signals barely above the threshold for detection. The difference in the azimuth angles of the spins, which may be used to check if spins are locked into resonant configurations, cannot be constrained. We observe that the best performances are obtained when the line of sight is perpendicular to the system's total angular momentum and that a sudden change of behavior occurs when a system is observed from angles such that the plane of the orbit can be seen both from above and below during the time the signal is in band. This study suggests that direct measurement of black hole spin by means of GWs can be as precise as what can be obtained from x-ray binaries.
120094772
Gravitational waves as deformations of embedded Einstein spaces
We show how approximate radiative solutions of Einstein's equations can be constructed using small deformations of Einstein spacetimes embedded into a pseudo-Euclidean flat space of higher dimension. Infinitesimal deformations are seen then as vector fields in EN. All geometrical quantities can be then expressed in terms of embedding functions zA and their deformations . Then we require the deformations to keep Einstein equations satisfied up to a given order in e. The system obtained is then analyzed in particular cases of the Minkowski and Schwarzschild manifolds taken as a starting point, and solutions of deformations of Einstein's equations displaying radiative behavior are found up to the third order of expansion in small parameter e.
119108663
Effect of calibration errors on Bayesian parameter estimation for gravitational wave signals from inspiral binary systems in the advanced detectors era
By 2015 the advanced versions of the gravitational-wave detectors Virgo and LIGO will be online. They will collect data in coincidence with enough sensitivity to potentially deliver multiple detections of gravitation waves from inspirals of compact-object binaries. This work is focused on understanding the effects introduced by uncertainties in the calibration of the interferometers. We consider plausible calibration errors based on estimates obtained during LIGO’s fifth and Virgo’s third science runs, which include frequency-dependent amplitude errors of 
∼ 
10 
% 
 and frequency-dependent phase errors of 
∼ 
3 
  
  
degrees 
 in each instrument. We quantify the consequences of such errors estimating the parameters of inspiraling binaries. We find that the systematics introduced by calibration errors on the inferred values of the chirp mass and mass ratio are smaller than 20% of the statistical measurement uncertainties in parameter estimation for 90% of signals in our mock catalog. Meanwhile, the calibration-induced systematics in the inferred sky location of the signal are smaller than 
∼ 
50 
% 
 of the statistical uncertainty. We thus conclude that calibration-induced errors at this level are not a significant detriment to accurate parameter estimation.