Metallicity gradients of disc stars for a cosmologically simulated galaxy

Abstract

We analyse for the first time the radial abundance gradients of the disc\nstars of a disc galaxy simulated with our three dimensional, fully cosmological\nchemodynamical galaxy evolution code GCD+. We study how [Fe/H], [N/O], [O/Fe],\n[Mg/Fe] and [Si/Fe] vary with galactocentric radius. For the young stars of the\ndisc, we found a negative slope for [Fe/H] and [N/O] but a positive [O/Fe],\n[Mg/Fe] and [Si/Fe] slope with radius. By analysing the star formation rate\n(SFR) at different radii, we found that the simulated disc contains a greater\nfraction of young stars in the outer regions, while the old stars tend to be\nconcentrated in the inner parts of the disc. This can explain the positive\n[alpha/Fe] gradient as well as the negative [N/O] gradient with radius. This\nradial trend is a natural outcome of an inside-out formation of the disc,\nregardless of its size and can thus explain the recently observed positive\n[alpha/Fe] gradients in the Milky Way disc open clusters.\n