Verifying the mass-metallicity relation in damped Lyman-alpha selected galaxies at 0.1<z<3.2

TL;DR

This study confirms the validity of a scaling relation linking galaxy mass and metallicity in DLA systems across a broad redshift range, improving stellar mass estimates and understanding of galaxy evolution.

Contribution

It provides a validated method to predict galaxy stellar masses from DLA metallicities and impact parameters, incorporating impact parameter dependence to reduce scatter.

Findings

Predicted and measured stellar masses agree within three orders of magnitude.

A significant correlation exists between impact parameter and metallicity offset.

Including impact parameter correction aligns DLA galaxies with the MZ relation at different redshifts.

Abstract

A scaling relation has recently been suggested to combine the galaxy mass-metallicity (MZ) relation with metallicities of damped Lyman-alpha systems (DLAs) in quasar spectra. Based on this relation the stellar masses of the absorbing galaxies can be predicted. We test this prediction by measuring the stellar masses of 12 galaxies in confirmed DLA absorber - galaxy pairs in the redshift range 0.1<z<3.2. We find an excellent agreement between the predicted and measured stellar masses over three orders of magnitude, and we determine the average offset $\langle C_{[M/H]} \rangle$ = 0.44+/-0.10 between absorption and emission metallicities. We further test if $C_{[M/H]}$ could depend on the impact parameter and find a correlation at the 5.5sigma level. The impact parameter dependence of the metallicity corresponds to an average metallicity difference of -0.022+/-0.004 dex/kpc. By including this metallicity vs. impact parameter correlation in the prescription instead of $C_{[M/H]}$, the scatter reduces to 0.39 dex in log M*. We provide a prescription how to calculate the stellar mass (M*,DLA) of the galaxy when both the DLA metallicity and DLA galaxy impact parameter is known. We demonstrate that DLA galaxies follow the MZ relation for luminosity-selected galaxies at z=0.7 and z=2.2 when we include a correction for the correlation between impact parameter and metallicity.