The time evolution of the Milky Way’s oxygen abundance gradient

Abstract

We study the evolution of oxygen abundance radial gradients as a function of time for the Milky Way Galaxy obtained with our Mulchem chemical evolution model. We review the recent data of abundances for different objects observed in our Galactic disc. We analyse with our models the role of the growth of the stellar disc, as well as the effect of infall rate and star formation prescriptions, or the pre-enrichment of the infall gas, on the time evolution of the oxygen abundance radial distribution. We compute the radial gradient of abundances within the disk, and its corresponding evolution, taking into account the disk growth along time. We compare our predictions with the data compilation, showing a good agreement. Our models predict a very smooth evolution when the radial gradient is measured within the optical disc with a slight flattening of the gradient from ∼ −0.057 dex kpc −1 at z = 4 until values around ∼ −0.015 dex kpc −1 at z = 1 and basically the same gradient until the present, with small differences between models. Moreover, some models show a steepening at the last times, from z = 1 until z = 0 in agreement with data which give a variation of the gradient in a range from −0.02 to −0.04 dex kpc −1 from t = 10 Gyr until now. The gradient measured as a function of the normalized radius R/R eff is in good agreement with findings by CALIFA and MUSE, and its evolution with redshift falls within the error bars of cosmological simulations.

Properties of the outer regions of spiral disks: abundances, colors and ages

“…• A grid of chemical evolution models with 16 dynamical masses in the range 10 10 to 10 13 M is calculated. A MWG-like model reproduces very well the observed radial distributions, as shown in Mollá et al (2015) and Mollá et al (2016b).…”

“…With N = 4 we obtain a MWG-like model that produces a good fit for the evolution of the solar region, and for the radial distributions of gas, stars, SFR, and elemental abundances of C, N, and O, as shown in Mollá et al (2015). We now check, in Mollá et al (2016b), the prescriptions in creating molecular gas from Fu et al (2010), based upon Blitz & Rosolowsky (2006): the H 2 fraction depends on total pressure, which, in turn, depends on gas and stellar surface densities. This model (BLI) is contrasted with STD.…”

“…As described in Mollá et al (2016a), we compute the radial mass distributions for 16 theoretical galaxies, following Salucci et al (2007), who define them in terms of M v ir and their associated rotation curves. The virial masses, defined as the total dynamical mass for a galaxy, are in the range M v ir ∈ [5 × 10 10 − 10 13 ] M , with associated disk masses in the range M disk ∈ [1.25 × 10 8 − 5.3 × 10 11 ] M .…”

“…Radial distributions for both gas phases were derived, but the inferred predicted ratios of atomic to molecular gas, and SF rate (SF R), were found to be at variance with those observed. We are computing a new grid of models with updated stellar yields - Mollá et al (2015)-, gas infall rates - Mollá et al (2016a)-, and molecular gas formation efficiency - Mollá et al (2016b). Our aim is to improve the predicted H 2 and SF R profiles, while maintaining abundance radial gradients in agreement with those observed.…”

The KLEVER Survey: spatially resolved metallicity maps and gradients in a sample of 1.2 < z < 2.5 lensed galaxies

“…A comparison with cosmological simulations that explore the effect of different feedback modes suggests a scenario where efficient mixing processes, which redistribute a significant amount of gas over large scales, are in place at these epochs (Gibson et al 2013b). However, predictions from analytical models, which assume fairly constant star formation profiles and no prescriptions about radial gas mixing, are also broadly consistent with the observed distribution of metallicity gradients observed in the galaxy population at z ∼1-2.5 (Mollá et al 2019). Galaxies showing a relatively homogeneous metal distribution across large spatial scales might also be consistent with a scenario of uniform disc mass assembly.…”