The star formation history of the Milky Way disc from Gaia DR3 and BGM FASt

Abstract

We use the Besan¸con Galaxy Model FASt Approximate Simulations (BGM FASt) framework together with the Approximate Bayesian Computation (ABC) algorithm to derive the posterior probability distribution function of the parameters defining the initial mass function (IMF) and the star formation history (SFH) in the Solar neighbourhood. We propose new strategies to unveil the influence of some BGM Std model ingredients from the Poissonian distance metric and the posterior distribution of the ratio between pseudo-simulation and data in the Hess diagrams. Gaia DR3 up to G=13 and a set of consolidated executions of the BGM FASt + ABC code on a Cloud Environment, using both different Mother Simulations and priors, allow us to confirm the existence of the star formation burst in the Galactic disc 2-4 Gyr ago proposed by [Mor et al. 2019]. Furthermore, for the composite IMF, we obtain the slopes of α2 and α3 constrained to the range [1.7, 2.8] and [1.8, 2.4], respectively, in agreement with recent values from the literature. The wide range of values obtained for the total stellar surface mass density of the thin disc at the Solar neighbourhood, between 30-50 M⊙pc−2, demonstrates that, before concluding on the set of best ingredients for the Galactic stellar population model, we shall loop the process to fit again both, the Galactic potential as described in Robin et al. [2022], and the BGM FASt IMF and SFH parameters.