Semi-analytic galaxies -- III. The impact of supernova feedback on the mass-metallicity relation

SOFIA A. CORA; CLAUDIA D. P. LAGOS; FLORENCIA COLLACCHIONI; CRISTIAN A. VEGA-MARTINEZ

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2018 vol. 481 p. 954 - 969

0035-8711

We use the semi-analytic model (SAM) of galaxy formation and evolution SAGcoupled with the MULTIDARK simulation MDPL2 to study the evolution of thestellar mass-gas metallicity relation of galaxies (MZR). We test severalimplementations of the dependence of the mass loading due to supernovae (SNe).We find that no evolution in the normalization of the MZR is obtained unless weintroduce an explicit scaling of the reheated and ejected mass with redshift as(1+z)β. The latter is in agreement with results from the FIREsimulations, and it should encompass small scale properties of the interstellarmedium varying over time, which are not captured in SAMs, as well as otherenergy sources in addition to SNe. Increasing β leads to strongerevolution of the MZR normalization; β=1.9 reproduces the observed MZRin the range 0<z<3.5. A stronger redshift dependence of outflows reducesthe levels of star formation at earlier epochs with the consequent decrease ofmetal production. This leads to a slower increase of the gas metallicitycompared to the stellar mass build-up. The cold gas can be contaminated eitherby receiving a direct injection of the material recycled by stellar winds andSNe or by gas cooling. The relative role of each process for a given stellarmass depends on the criterion adopted to regulate the fate of the recycledmaterial. However, modifying the metal loading of the outflows has mild impacton the zero-point evolution and does not affect our conclusions.