JJ model: a flexible tool for SFR reconstruction

Kseniia Sysoliatina

Tuesday, Dec. 6th, 9:55CET

We present a public tool for the Milky Way (MW) stellar population synthesis, Just-Jahreiß (JJ) model. It was locally calibrated against Gaia DR2. We identified two star-formation (SF) bursts within the recent 3 Gyr of the local SF rate (SFR) history. The model is now generalized for a wide range of Galactocentric distances. The JJ model describes an axisymmetric MW. It includes exponential thin and thick disks, atomic and molecular gas layers, spherical stellar halo, and cored isothermal dark matter sphere. The overall thin-disk thickness is independent of radius, and the radial variation of the thin-disk SFR reflects the inside-out disk growth. A smooth power-law SFR continuum can be modified by an arbitrary number of Gaussian peaks consisting of dynamically hot stars, thus, representing gas infall episodes. For the stellar population synthesis, the JJ model is complemented by three alternative isochrone sets – PARSEC, MIST, and BaSTI. The generalized JJ model is a publicly available tool for studying different stellar populations across the MW disk. It can be particularly useful for reconstructing the thin-disk SFR because the JJ model has a fine time resolution of 25 Myr and a variety of different SFR shapes can be constructed within its framework. Both simultaneous and sequential formation of the thick and thin disk can be tested. With the Gaia DR3 extended sample, we aim for constraining the rest of the JJ-model parameters at different radii, and therefore, to reveal the details of the MW evolutionary history.