Galactic Archaeology with asteroseismic ages: Evidence for delayed gas infall in the formation of the Milky Way disc

Context. Precise stellar ages from asteroseismology have become available and can help to set stronger constraints on the evolution of the Galactic disc components. Recently, asteroseismology has confirmed a clear age difference in the solar annulus between two distinct sequences in the [alpha/Fe] versus [Fe/H] abundance ratios relation: the high-alpha and low-alpha stellar populations. Aims. We aim to reproduce these new data with chemical evolution models including different assumptions for the history and number of accretion events. Methods. We tested two different approaches: a revised version of the two-infall model where the high-alpha phase forms by a fast gas accretion episode and the low-alpha sequence follows later from a slower gas infall rate, and the parallel formation scenario where the two disc sequences form coevally and independently. Results. The revised two-infall model including uncertainties in age and metallicity is capable of reproducing: i) the [alpha/Fe] versus [Fe/H] abundance relation at different Galactic epochs, ii) the age metallicity relation and the time evolution [alpha/Fe]; iii) the age distribution of the high-alpha and low-alpha stellar populations, iv) the metallicity distribution function. The parallel approach is not capable of properly reproducing the stellar age distribution, in particular at old ages. Conclusions. The best chemical evolution model is the revised two-infall one, where a consistent delay of similar to 4.3 Gyr in the beginning of the second gas accretion episode is a crucial assumption to reproduce stellar abundances and ages.