Status Report

Testing general relativity by micro-arcsecond global astrometry

By SpaceRef Editor
January 17, 2003
Filed under , ,

Astrophysics, abstract

From: Alberto Vecchiato <[email protected]>
Date: Thu, 16 Jan 2003 15:50:04 GMT (41kb)

Testing general relativity by micro-arcsecond global astrometry

Alberto Vecchiato,
Mario G. Lattanzi,
Beatrice Bucciarelli,
Maria Teresa Crosta,
Fernando de Felice,
Mario Gai

Comments: 7 pages, 2 figures, to be published in A&A

The global astrometric observations of a GAIA-like satellite were modeled
within the PPN formulation of Post-Newtonian gravitation. An extensive
experimental campaign based on realistic end-to-end simulations was conducted
to establish the sensitivity of global astrometry to the PPN parameter gamma,
which measures the amount of space curvature produced by unit rest mass. The
results show that, with just a few thousands of relatively bright,
photometrically stable, and astrometrically well behaved single stars, among
the ~10^9 objects that will be observed by GAIA, gamma can be estimated after
1 year of continuous observations with an accuracy of ~10^{-5} at the 3sigma
level. Extrapolation to the full 5-year mission of these results based on the
scaling properties of the adjustment procedure utilized suggests that the
accuracy of simeq 2×10^{-7}, at the same 3sigma level, can be reached with
~10^6 single stars, again chosen as the most astrometrically stable among the
millions available in the magnitude range V=12-13. These accuracies compare
quite favorably with recent findings of scalar-tensor cosmological models,
which predict for gamma a present-time deviation, |1-gamma|, from the General
Relativity value between 10^{-5} and 10^{-7}.

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