Quasar Proper Motions and Low‐Frequency Gravitational Waves

Gwinn, C. R.; Eubanks, T. M.; Pyne, Ted; Birkinshaw, Mark; Matsakis, Demetrios

doi:10.1086/304424

Cited by 103 publications

(146 citation statements)

References 29 publications

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“…These issues are however not discussed here. In the frame rotator solution, the six parameters must be complemented by three more parameters a X , a Y , a Z taking into account the acceleration of the solar-system barycentre in a cosmological frame (Bastian 1995;Gwinn et al 1997;Kopeikin & Makarov 2006). Such an acceleration, by the vector α, will cause a systematic "streaming" (dipole) pattern of the apparent proper motions of extragalactic objects, described by…”

Section: Determination Of the Frame Rotator Parametersmentioning

confidence: 99%

The astrometric core solution for theGaiamission

Lindegren

Lammers

Hobbs

et al. 2012

A&A

370

624

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Context. The Gaia satellite will observe about one billion stars and other point-like sources. The astrometric core solution will determine the astrometric parameters (position, parallax, and proper motion) for a subset of these sources, using a global solution approach which must also include a large number of parameters for the satellite attitude and optical instrument. The accurate and efficient implementation of this solution is an extremely demanding task, but crucial for the outcome of the mission. Aims. We aim to provide a comprehensive overview of the mathematical and physical models applicable to this solution, as well as its numerical and algorithmic framework. Methods. The astrometric core solution is a simultaneous least-squares estimation of about half a billion parameters, including the astrometric parameters for some 100 million well-behaved so-called primary sources. The global nature of the solution requires an iterative approach, which can be broken down into a small number of distinct processing blocks (source, attitude, calibration and global updating) and auxiliary processes (including the frame rotator and selection of primary sources). We describe each of these processes in some detail, formulate the underlying models, from which the observation equations are derived, and outline the adopted numerical solution methods with due consideration of robustness and the structure of the resulting system of equations. Appendices provide brief introductions to some important mathematical tools (quaternions and B-splines for the attitude representation, and a modified Cholesky algorithm for positive semidefinite problems) and discuss some complications expected in the real mission data. Results. A complete software system called AGIS (Astrometric Global Iterative Solution) is being built according to the methods described in the paper. Based on simulated data for 2 million primary sources we present some initial results, demonstrating the basic mathematical and numerical validity of the approach and, by a reasonable extrapolation, its practical feasibility in terms of data management and computations for the real mission.

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Section: Determination Of the Frame Rotator Parametersmentioning

confidence: 99%

The astrometric core solution for theGaiamission

Lindegren

Lammers

Hobbs

et al. 2012

A&A

370

624

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“…112 Therefore, precise measurement of proper motion of quasars would be a method to detect ultra-low frequency (10 fHz -300 pHz) gravitational waves. Gwinn et al 113 used this method to constrain the normalized spectral energy density of stochastic GWs with frequencies less than 2  10 −9 Hz and greater than 3  10 −18 Hz (including frequencies in the ultra-low frequency band) to less than 0.11 h −2 (95 % confidence) times the critical closure density of our Universe. In Fig.…”

Section: Ultralow Frequency Band (10 Fhz -300 Phz)mentioning

confidence: 99%

Gravitational waves: Classification, methods of detection, sensitivities and sources

Kuroda

Pan

2015

Int. J. Mod. Phys. D

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After giving a brief introduction and presenting a complete classification of gravitational waves (GWs) according to their frequencies, we review and summarize the detection methods, the sensitivities, and the sources. We notice that real-time detections are possible above 300 pHz. Below 300 pHz, the detections are possible on GW imprints or indirectly. We are on the verge of detection. The progress in this field will be promising and thriving. We will see improvement of a few orders to several orders of magnitude in the GW detection sensitivities over all frequency bands in the next hundred years.

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“…This will be achieved during the process of constructing a Gaia-based ICRF with several 10,000s QSOs as explained in (Mignard & Klioner, 2007). Another pattern allows one to constraint (Pyne et al, 1996, Gwinn et al, 1997 possible gravitational wave flux with a frequency ω < 3 × 10 −9 Hz. The accuracy that can be expected from Gaia is Ω GW < (0.001 − 0.005) h −2 , h being the normalized Hubble constant h = H 0 /(100 km/s/Mpc).…”

Section: Global Testsmentioning

confidence: 99%

Gaia: Relativistic modelling and testing

Mignard

2009

Proc. IAU

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Abstract. Gaia is an ambitious space astrometry mission of ESA with a main objective to map the sky in astrometry and photometry down to a magnitude 20 by the end of the next decade. Given its extreme astrometric accuracy and the repeated observations over five years, the observation modelling is done in a fully relativistic framework and several tests of General Relativity or of its extensions can be carried out during the data processing. The paper presents an overview of the current activities in this area and of the expected performances.

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Quasar Proper Motions and Low‐Frequency Gravitational Waves

Cited by 103 publications

References 29 publications

The astrometric core solution for theGaiamission

The astrometric core solution for theGaiamission

Gravitational waves: Classification, methods of detection, sensitivities and sources

Gaia: Relativistic modelling and testing

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