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Astrometric effects of a stochastic gravitational wave background

Book, Laura G. and Flanagan, Éanna É. (2011) Astrometric effects of a stochastic gravitational wave background. Physical Review D, 83 (2). Art. No. 024024. ISSN 2470-0010.

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A stochastic gravitational wave background causes the apparent positions of distant sources to fluctuate, with angular deflections of order the characteristic strain amplitude of the gravitational waves. These fluctuations may be detectable with high precision astrometry, as first suggested by Braginsky et al. in 1990. Several researchers have made order of magnitude estimates of the upper limits obtainable on the gravitational wave spectrum Ω_(gw)(f), at frequencies of order f~1  yr^(-1), both for the future space-based optical interferometry missions GAIA and SIM, and for very long baseline interferometry in radio wavelengths with the SKA. For GAIA, tracking N~10^6 quasars over a time of T~1  yr with an angular accuracy of Δθ∼10μ as would yield a sensitivity level of Ω_(gw)~(Δθ)^2/(NT^2H_0^2)~10^(-6), which would be comparable with pulsar timing. In this paper we take a first step toward firming up these estimates by computing in detail the statistical properties of the angular deflections caused by a stochastic background. We compute analytically the two-point correlation function of the deflections on the sphere, and the spectrum as a function of frequency and angular scale. The fluctuations are concentrated at low frequencies (for a scale invariant stochastic background), and at large angular scales, starting with the quadrupole. The magnetic-type and electric-type pieces of the fluctuations have equal amounts of power.

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Additional Information:© 2011 American Physical Society. Received 20 September 2010; published 20 January 2011. L. G. B. acknowledges the support of the National Science Foundation. E. F. thanks the Theoretical Astrophysics Including Relativity Group at Caltech and the Department of Applied Mathematics and Theoretical Physics at the University of Cambridge for their hospitality as this paper was being written. This research was supported in part by NSF Grants No. PHY-0757735 and PHY-0555216.
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Issue or Number:2
Classification Code:PACS: 04.30.Db, 98.70.Vc
Record Number:CaltechAUTHORS:20110307-093938631
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Official Citation:Astrometric effects of a stochastic gravitational wave background Laura G. Book and Éanna É. Flanagan Published 20 January 2011 (15 pages) 024024
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:22676
Deposited By: Ruth Sustaita
Deposited On:08 Mar 2011 21:40
Last Modified:03 Oct 2019 02:39

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