High-redshift Damped Ly-alpha Absorbing Galaxy Model Reproducing the N(HI)-Z Distribution

Understand

We investigate how damped Lyman-$\alpha$ absorbers (DLAs) at z ~ 2-3, detected in large optical spectroscopic surveys of quasars, trace the population of star-forming galaxies.

• Building on previous results, we construct a model based on observed and physically motivated scaling relations in order to reproduce the bivariate distributions of metallicity, Z, and HI column density, N(HI).
• Furthermore, the observed impact parameters for galaxies associated to DLAs are in agreement with the model predictions.
• The model strongly favours a metallicity gradient, which scales with the luminosity of the host galaxy, with a value of $\gamma$* = -0.019 $\pm$ 0.008 dex kpc$^{-1}$ for L* galaxies that gets steeper for fainter galaxies.