Volume 399, Number 1, February III 2003
|Page(s)||337 - 342|
|Section||Celestial mechanics and astrometry|
|Published online||05 February 2003|
Testing general relativity by micro-arcsecond global astrometry
Istituto di Fisica “G. Galilei”, Via Marzolo 8, 35100 Padova, Italy
2 Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Padova
3 Centro per gli Studi e le Attività Spaziali “G. Colombo” (CISAS), Padova
4 INAF, Osservatorio Astronomico di Torino, 10025 Pino Torinese TO, Italy
Corresponding author: M. G. Lattanzi, email@example.com
Accepted: 27 November 2002
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 γ, 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 ~109 objects that will be observed by GAIA, γ can be estimated after 1 year of continuous observations with an accuracy of ~10-5 at the 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 , at the same level, can be reached with ~ 106 single stars, again chosen as the most astrometrically stable among the millions available in the magnitude range . These accuracies compare quite favorably with recent findings of scalar-tensor cosmological models, which predict for γ a present-time deviation, , from the General Relativity value between 10-5 and 10-7 .
Key words: astrometry / relativity / gravitation / space vehicles: instruments
© ESO, 2003
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