http://arxiv.org/abs/1806.06038
One of the main goals of modern astrophysics is to understand how galaxies form and evolve from the Big Bang until the present-time. The Gaia mission was conceived to unravel the assembly history of our own Galaxy, the Milky Way. Gaia’s recently delivered second data release allows tackling this objective like never before. Here we analyse the kinematics, chemistry, age and spatial distribution of stars in a relatively large volume around the Sun that are mainly linked to two major Galactic components, the thick disk and the stellar halo. We demonstrate that the inner halo is dominated by debris from an object slightly more massive than the Small Magellanic Cloud, and which we refer to as Gaia-Enceladus. The accretion of Gaia-Enceladus must have led to the dynamical heating of the precursor of the thick disk and hence contributed to the formation of this component approximately 10 Gyr ago.
A. Helmi, C. Babusiaux, H. Koppelman, et. al.
Mon, 18 Jun 18
41/54
Comments: 16 pages, 8 figures, submitted