Chemical Evolution with Radial Mixing Redux: a detailed model for formation and evolution of the Milky Way

Abstract

We present a multizone galactic chemical evolution (GCE) model for the Milky Way that takes the most recently updated yields of major nucleosynthesis channels into account. It incorporates physical processes commonly found in previous GCE models like gas feedback from supernovae and star formation, the radial flow of gas in the disc, and the infall of fresh gas, along with stellar scattering processes like radial migration. We individually analyse the effect of different physical processes present in our model on the observed properties of the Galaxy. The radial flow of gas in the disc plays an important role in establishing the radial gradient for [Fe/H] in the low-[α/Fe] sequence. Our model with one episode of smooth gas infall and constant star formation efficiency is capable of reproducing the observed ([Fe/H], [α/Fe]) distribution of stars at different (R, |z|) positions in the Milky Way. Our results point to the rapid evolution of [α/Fe] after the onset of Type Ia supernovae and a high star formation rate during the formation of the high-[α/Fe] sequence as the origin of dual peaks in [α/Fe]. A secondary infall is unnecessary to reproduce the [α/Fe] gap and chemical spread in the disc in our model. We additionally compare the median age for various mono-abundance populations and the age–metallicity relation at different (R, |z|) positions from our fiducial model to observations. We discuss our results in relation to other related work in detail.