Fakultät für Physik und Astronomie
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An update of the Milky Way disk model and its application: Age-metallicity relation from 4 to 14 kpc based on the JJ model and APOGEE data

Kseniia Sysoliatina , ARI

The semi-analytic Just-Jahreiss (JJ) model of the Galactic disk has been recently calibrated by us in the Solar neighborhood against the Gaia DR2 stars. We identified two star formation (SF) bursts that happened during the recent 4 Gyr. Now we present a global version of the JJ model applicable to a wide range of Galactocentric distances. This generalized JJ model includes exponential thin and thick disk and also atomic and molecular gas layers, as well as the flattened stellar halo and DM halo in the form of a cored isothermal sphere. The overall thickness of the thin disk is assumed constant at all radii, but flaring can be also modeled. The radial variation of the thin-disk star formation rate (SFR) reflects the expected inside-out disk growth scenario. Motivated by our findings for the Solar neighborhood, we allow the smooth power-law SFR to be modified by an arbitrary number of additional Gaussian peaks. Also, the vertical kinematics of the stellar populations associated with these episodes of the SF excess can differ from the kinematics prescribed by the age-velocity dispersion relation for the thin-disk populations of the same age. Using the observed metallicity distributions of the APOGEE Red Clump giants, we constrained the thin- and thick-disk age-metallicity relation for the distances 4 - 14 kpc. The public code of the JJ model is complemented by the two sets of isochrones, PARSEC and MIST. The generalized JJ model is a new stellar population synthesis tool that can be useful for a variety of tasks of Galactic archaeology, including the reconstruction of the Milky-Way disk formation history.

ARI Institute Colloquium
9 Dec 2021, 11:15
ARI, Moenchhofstrasse 12-14, Seminarraum 1, 1.OG

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