DLA kinematics and outflows from starburst galaxies

TL;DR

This study uses high-resolution simulations to explore how starburst galaxy clumps produce winds and outflows, explaining observed high-velocity neutral gas dispersions in damped Ly-alpha systems.

Contribution

It demonstrates that resolving cold, dense clouds at 12 pc resolution is crucial for modeling effective thermal feedback-driven outflows in starburst galaxy environments.

Findings

Outflows reach velocities up to several hundred km/s.

High-resolution modeling captures multiphase medium and hot bubble formation.

Feedback can entrain neutral clumps, producing complex absorption features.

Abstract

We present results from a numerical study of the multiphase interstellar medium in sub-Lyman-break galaxy protogalactic clumps. Such clumps are abundant at z=3 and are thought to be a major contributor to damped Ly-alpha absorption. We model the formation of winds from these clumps and show that during star formation episodes they feature outflows with neutral gas velocity widths up to several hundred km/s. Such outflows are consistent with the observed high-velocity dispersion in DLAs. In our models thermal energy feedback from winds and supernovae results in efficient outflows only when cold (~ 300 K), dense (> 100 msun/pc^3) clouds are resolved at grid resolution of 12 pc. At lower 24 pc resolution the first signs of the multiphase medium are spotted; however, at this low resolution thermal injection of feedback energy cannot yet create hot expanding bubbles around star-forming regions -- instead feedback tends to erase high-density peaks and suppress star formation. At 12 pc resolution feedback compresses cold clouds, often without disrupting the ongoing star formation; at the same time a larger fraction of feedback energy is channeled into low-density bubbles and winds. These winds often entrain compact neutral clumps which produce multi-component metal absorption lines.