The Relativistic All-Sky Analysis with GAIA

Abstract

By providing an homogenous all-sky survey of high precision parallaxes, space motion (proper motions and radial velocities) and astrophysical characteriza- tion for more than one billion stars throughout the Galaxy and thanks to the depth of the volume achievable, Gaia will deliver a huge amount of astrometric, spectroscopic, and photometric data. Gaia will contribute also to the determi- nation of an optical reference frame by observing many thousands of quasars. In doing so Gaia will have a huge impact across many fields, including many branches of stellar astrophysics (details of the structure and stellar evolutionary phases), exoplanets, solar system objects, the cosmic distance ladder (through a model independent of the primary calibrators) and fundamental physics. New “accurate” distances and motions of the stars within our Galaxy will provide access to the cosmological signatures left in the disk and halo offering inde- pendent, direct and detailed comparisons the predictions of the most advanced cosmological simulations. But all the above goals will not be achieved without the correct characterization and exploitation of the “relativistic”, i.e. very high accuracy, astrometric data. Since a Gaia-like observer is positioned inside the Solar System, the measurements are performed in a weak gravitational regime which can be regarded as “strong” when one has to compare these slow varying fields with the accuracy achievable by Gaia.