Modelling intergalactic low ionisation metal absorption line systems near the epoch of reionization

Abstract

We interpret observations of intergalactic low ionisation metal absorption systems at redshifts z $\gtrsim$5 in terms of pressure-confined clouds. We find clouds confined by the expected pressure of galactic haloes with masses $11<\log M_h/h^{-1}{M}_{\odot }<12$ provide a good description of the column density ratios between low ionisation metal absorbers. Some of the ratios, however, require extending conventional radiative transfer models of irradiated slabs to spherical (or cylindrical) clouds to allow for lines of sight passing outside the cores of the clouds. Moderate depletion of silicon onto dust grains is also indicated in some systems. The chemical abundances inferred span the range between solar and massive-star dominated stellar populations as may arise in starburst galaxies. The typical HI column densities matching the data correspond to Damped Lyman-$\alpha$ Absorbers (DLAs) or sub-DLAs, with sizes of 40 pc to 3 kpc, gas masses $3.5<\log M_c/M_{\odot }<8$ and metallicites $0.001-0.01Z_{\odot }$. Such systems continue to pose a challenge for galaxy-scale numerical simulations to reproduce.

19 pages, 10 figures, 12 Tables, submitted to MNRAS, comments welcome

References in corpus (17)

• The Circumgalactic Medium
• Nucleosynthetic signatures of the first stars
• Evidence of patchy hydrogen reionization from an extreme Ly$\alpha$ trough below redshift six
• Conditions for Reionizing the Universe with A Low Galaxy Ionizing Photon Escape Fraction
• Faint AGNs at z>4 in the CANDELS GOODS-S field: looking for contributors to the reionization of the Universe
• Metallicity Evolution of Damped Lyman-alpha Systems out to z~5
• HE 0557-4840 - Ultra-Metal-Poor and Carbon-Rich
• Probing the Formation of the First Low-Mass Stars with Stellar Archaeology
• A downturn in intergalactic CIV as redshift 6 is approached
• The Impact of Galactic Feedback on the Circumgalactic Medium
• The oldest and most metal poor stars in the APOSTLE Local Group simulations
• Mg II absorbers: metallicity evolution and cloud morphology
• A deep search for metals near redshift 7: the line-of-sight towards ULAS J1120+0641
• Early metal enrichment of gas-rich galaxies at z~5
• Metal-enriched Galaxies in the First ~1 Billion Years: Evidence of a Smooth Metallicity Evolution at z ~ 5
• Gas around galaxy haloes - III: hydrogen absorption signatures around galaxies and QSOs in the Sherwood simulation suite
• Bursty star formation feedback and cooling outflows