Attività del Dipartimento
Colloqui di Fisica.jpg) Astrometric Cosmology in the Gaia era.
Status and prospects after over three years of science operations
Mario Lattanzi 07-11-2017 - 15:00 AULA B - Via Della Vasca Navale 84
The concept of precisely gauging a gravity-dominated Universe like ours through the individual observations of its fundamental constituents, the stars, immediately calls astrometry, the oldest quantitative specialty of astronomy, into play. For, the accurate measurement of the motions of stars in our Galaxy can provide access to cosmological signatures in its disk and halo, while astrometric experiments from within our Solar System can uniquely probe possible deviations from General Relativity. This talk will address the fact that, with the launch of the Gaia satellite, astrometry has reached such levels to become a key player in the fields of local cosmology and experimental gravitation. It will be shown how accurate distances and absolute kinematics at the scale of the Milky Way, a revolution for stellar astrophysics, can, for the first time in situ, account for the predictions of the CDM model for the Galactic halo; and how, eventually, can map out the distribution of dark matter, or other formation mechanisms, required to explain the signatures recently identified in the old component of the thick disk. Results from first release (DR1) data and updates on the status of the mission, orbiting L2 since January 2014 and in nominal (science) observation mode since July 18, 2014, are presented to the extent possible with the help of results from the astrometric pipelines operating at the Italian data processing center (DPCT). Final notes will dwell on to what extent the Gaia satellite can fulfill the expectations of astrometric cosmology and on what must instead be left to future, specifically designed, experiments. |