Reproducing the Kinematics of Damped Lyman-alpha Systems

TL;DR

This study uses advanced cosmological simulations to accurately reproduce the kinematic properties of Damped Lyman-alpha Systems, highlighting the importance of feedback mechanisms and detailed ionisation modeling.

Contribution

The paper demonstrates improved simulation matching of DLA kinematics by incorporating strong feedback and detailed metal ionisation modeling, advancing understanding of small, faint galaxy halos.

Findings

Better match of velocity width distribution compared to earlier work

Reproduction of the correlation between velocity width and metallicity

Identification of residual discrepancies in absorption profile shapes

Abstract

We examine the kinematic structure of Damped Lyman-alpha Systems (DLAs) in a series of cosmological hydrodynamic simulations using the AREPO code. We are able to match the distribution of velocity widths of associated low ionisation metal absorbers substantially better than earlier work. Our simulations produce a population of DLAs dominated by halos with virial velocities around 70 km/s, consistent with a picture of relatively small, faint objects. In addition, we reproduce the observed correlation between velocity width and metallicity and the equivalent width distribution of SiII. Some discrepancies of moderate statistical significance remain; too many of our spectra show absorption concentrated at the edge of the profile and there are slight differences in the exact shape of the velocity width distribution. We show that the improvement over previous work is mostly due to our strong feedback from star formation and our detailed modelling of the metal ionisation state.