The oxygen abundance gradients of galaxies in the Eagle simulations

Patricia B. Tissera Universidad Andres Bello

Millennium Institute of Astrophysics

Metallicity gradients in disc galaxies

Ho+2015

Sanchez+2013; Sanchez-Mengano +2016

What drives metallicity gradients in

discs ?

Belfiore+2017

Selected from 100 Mpc volume.At least ~2000 baryonic particles.Dynamical decomposition: O/H profiles determined for the disc components with at least 100 star forming regions. Local environment characterise by count-in-cell NCIC.Total sample of 592 simulated galaxies with a variety of morphologies in different environments.

Y. Rosas-Guevara (UNAB), R. Machado (U. Curitiba), T. Theuns (ICC), R. Bowers

(ICC), C. Lagos (Perth)

EAGLE simulations: global properties

Three environments are defined:low (~100 members), intermediate (~300 members) and high (~100) density

Gas-phase abundances of disc galaxies: dependence on stellar mass

Gas-phase abundances of disc galaxies: dependence on stellar mass

LM

HM

LM

HM

Dependence on recent star formation history

Discs with positive gas-phase metallicity gradients are found in galaxies which quenched the star formation activity before

compared to those with negative in the same mass range.

Galactic fountain are not efficiently working and could be a solution if they act in the central regions.

Galaxies selected not to have a recent merger event (1:10 & < 3Gyr) show a trend with stellar mass. They have D/T >0.5 on average.

Galaxies selected by D/T > 0.5 and gas fraction > 0.15 show a trend with stellar mass. These galaxies show a larger dispersion for smaller masses.

Dependence on recent merger history and D/T

Dependence on environment

Fraction of galaxies with positive metallicity gradients

Fraction of galaxies with recent mergers

Fraction of gas-rich galaxies (>15%)

45% 40% 27%

Dependence on environment

Ma+2017Tissera+2016

Summary

* Metallicity gradients of the EAGLE discs are negative, on average, albeit flatter than observations, S(OH) ~ -0.01 dex/kpc.

* Galaxies with no recent mergers determine a correlation with stellar mass; they have well-defined discs and are gas-rich. Galaxies with a recent merger show a flat relation.

* There is a dependence of gas-phase metallicity gradients on local environment since the merger rate and the gas fraction vary with environment.

Results indicate too strong central outflows + weak impact of fountain accretion.

On going work: evolution of the gas-phase metallicity gradients and the stellar metallicity gradients.