Constraining gas metal mixing strength with MW simulations

Jorge Sarrato Alós, Chris Brook, Arianna Di Cintio


The solar neighbourhood has been classically considered a very well mixed region (highly homogenous metallicity close to solar values). Recently however, contradicting works have been published on this topic: [De Cia, 2021] defends the existence of large spread (~1 dex) in the metallicity of neutral gas in the ISM of the solar neighbourhood, and [Esteban, 2022] argues in favour of the classical vision of a well mixed solar neighbourhood. This sets a debate on the evolution of our galaxy, partly driven by metal mixing processes, which highly influence the evolution of the Metal Distribution Function (MDF), as stated by [Rennehan, 2021]. We use cosmological hydrodynamic simulations from the NIHAO project to test the influence of metal mixing in the evolution of a Milky Way(MW)-like galaxy. We compare the same simulated galaxy with and without metal diffusion to data from [De Cia, 2021], [Esteban, 2022] and GALAH DR3 in order to determine how much metal mixing is needed in MW simulations in order to reproduce observations. The use of adequate metal mixing strength will result in more realistic simulations, improving their ability to make predictions.