To detect the dwarf galaxies in the halo of the MW a whole automatic pipeline that detects the substructures in proper motion space in each part of the sky has been prepared. The application to the Gaia DR2 allowed the detection of the Sagittarius dwarf and its tidal stream, obtaining the largest samples of stars (Antoja et al. 2020, A&A, 635:L3) and of RR Lyrae Ramos, Antoja, et al. 2020, A&A, 638:A104) to date and its first all-sky and continuous proper motions tracks, which do not match the existing models.
Different analysis techniques were developed to study the large-scale kinematics of the Galaxy disk for the first time. The so-called phase space spiral was discovered (Antoja et al. 2018, Nature 561:360–362) and was hypothesised to be a signature of phase mixing after a strong perturbation back to about 300-900 million years ago, pointing towards Sagittarius as the main cause. This shows that the disk of our Galaxy is highly responsive to perturbations and time-dependent, challenging one of the most used premises in galactic dynamics: the equilibrium of the disk. The moving groups were detected and characterised well beyond the Solar Neighbourhood for the first time (Ramos, Antoja, et al 2018, A&A, 619:72), establishing that some groups present constant vertical angular momentum with Galactic radius and others constant energy, from which it was hypothesised that there must be different dynamical mechanisms in place (spiral arms, Galactic bar, and external perturbations). Finally, different substructures in the outermost parts of the MW Disk (Monoceros, ACS, TriAnd) were revealed and studied, the data favouring models that explain these structures as made of disk stars perturbed by an external galaxy more than remnants of accreted galaxies as previously suggested.
A new code was prepared to integrate back in time the orbits of the Young Local Associations and find their age. The dynamical age of β Pictoris was determined (Miret et al, 2020, A&A, in press) with a precision three times better than before and that for the first time is consistent with independent determinations with other methods, thus solving a long standing puzzle. An improved list of member and some new radial velocities were also presented.
During the action coordination and preparation tasks of the WEAVE Low Resolution Disk sub-survey as well as several tasks related to the Gaia Early Data Release 3 (EDR3, 3/12/2020) have been performed (e.g. Gaia collaboration, Antoja, et al, submitted to A&A in October 2020, Fabricius et al, to be submitted in Fall 2020).
All results (list of member candidates of Sagittarius, of the outer disk structures, of β Pictoris) have been made public and are currently being considered as targets for surveys such as WEAVE to measure radial velocities and chemical abundances. The proper motions tracks of Sagittarius are publicly available to be used to fit the Galaxy’s gravitational potential and the tables of moving groups are being used for comparisons with different methods and simulations. The pipelines prepared during the action and applied successfully to DR2 will be applied to the EDR3 for the detection of fainter dwarfs in the halo and the explorations of farther disk regions. The results of the project have been presented in five accepted publications in international peer reviewed articles, and three more articles are in final stages of preparation (Ramos, Antoja, to be submitted to A&A, October-November 2020; Garcia-Conde, Roca-Fabrega, Antoja, et al., to be submitted to ApJ before end of 2020; Gaia collaboration, Antoja et al., submitted to A&A 2020), and presented in several international conferences.
