We are deriving the SFH across the Milky Way thin and thick disks by fitting Gaia DR2 CMDs.
We have constructed CMDs and computed SFHs for a number of layers parallel to the Milky Way plane, at different heights up to Z=2 Kpc above and below the plane, and close to the solar radius. A summary of the results is displayed in the Figure (see caption for details). We will call these SFHs 'dynamically evolved SFHs' because the stellar sample present in each volume is potentially affected by stellar migration. These effects will be taken into account a posteriori in our analysis of the results. Several epochs of enhanced star formation (~10, 6 and 2 ago) can be observed close to the plane, up to |Z| ~ 400 pc. At larger distances from the plane, the younger star forming epochs gradually diminish their relative strength. This results in a smooth change in the SFR(t) as a function of height |Z|, with mean age increasing with |Z|. The distinct epoch of star formation between 12 and 8 Gyr ago may correspond to the formation of the thick disk. Thanks to the CMD fitting method, a SFH profile across the Galactic disk has been obtained for the first time. This technique holds a great potential for unraveling the history of formation of the different component of our Galaxy, using Gaia data alone.
