The impact of different physical processes on the statistics of Lyman-limit and damped Lyman α absorbers

2013/07/31 by Gabriel Altay, Tom Theuns, Joop Schaye +2 · 46 citations
Physics and Astronomy · #Astrophysics #Astrophysics and Star Formation Studies #Context (archaeology) #Dark Ages #Galaxies: Formation, Evolution, Phenomena #Galaxy #Gamma-ray bursts and supernovae #Hydrogen #Intergalactic medium #Interstellar medium #Lyman limit #Physics #Quantum mechanics #Radiative transfer #Reionization #Star formation #Stars #Supernova #astro-ph.CO

paper · pdf · doi:10.1093/mnras/stt1765

published in Monthly Notices of the Royal Astronomical Society 436(3), 2689-2707 (Oxford University Press) · 21 pages, 16 figures, accepted for publication in MNRAS. Data and code to reproduce all figures can be found at https://bitbucket.org/galtay/hi-cddf-owls-1

arxiv created 2013/09/26 · openalex publication_date 2013/10/16 · arxiv updated 2015/06/16 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

We compute the z = 3 neutral hydrogen column density distribution function f(NHi) for 19 simulations drawn from the Overwhelmingly Large Simulations project using a post-processing correction for self-shielding calculated with full radiative transfer of the ionizing background radiation. We investigate how different physical processes and parameters affect the abundance of Lyman-limit systems (LLSs) and damped Lyman α absorbers including: (i) metal-line cooling; (ii) the efficiency of feedback from supernovae and active galactic nuclei; (iii) the effective equation of state for the interstellar medium; (iv) cosmological parameters; (v) the assumed star formation law and (vi) the timing of hydrogen reionization. We find that the normalization and slope, |\mathcal D = d log ₁₀ f /d log ₁₀ N_\rm H \small I|⁠, of f(NHi) in the LLS regime are robust to changes in these physical processes. Among physically plausible models, f(NHi) varies by less than 0.2 dex and |\mathcal D| varies by less than 0.18 for LLSs. This is primarily due to the fact that these uncertain physical processes mostly affect star-forming gas which contributes less than 10 per cent to f(NHi) in the LLS column density range. At higher column densities, variations in f(NHi) become larger (approximately 0.5 dex at f(NHi) = 1022 cm-2 and 1.0 dex at f(NHi) = 1022 cm-2) and molecular hydrogen formation also becomes important. Many of these changes can be explained in the context of self-regulated star formation in which the amount of star-forming gas in a galaxy will adjust such that outflows driven by feedback balance inflows due to accretion. Tools to reproduce all figures in this work can be found at the following url: https://bitbucket.org/galtay/hi-cddf-owls-1

Citations

• Absorption-line systems in simulated galaxies fed by cold streams
• The Keck+Magellan Survey for Lyman Limit Absorption. I. The Frequency Distribution of Super Lyman Limit Systems
• THE ATOMIC-TO-MOLECULAR TRANSITION IN GALAXIES. II: H I AND H2COLUMN DENSITIES
• Surveys forz > 3 Damped Lyα Absorption Systems: The Evolution of Neutral Gas
• Damped Lyman α systems in galaxy formation simulations
• AHUBBLE SPACE TELESCOPESTUDY OF LYMAN LIMIT SYSTEMS: CENSUS AND EVOLUTION
• On the Importance of Local Sources of Radiation in Cosmological Absorption Systems
• CLOUDY 90: Numerical Simulation of Plasmas and Their Spectra
• E pur si muove:Galilean-invariant cosmological hydrodynamical simulations on a moving mesh
• DAMPED LYα SYSTEMS
• Three‐YearWilkinson Microwave Anisotropy Probe(WMAP) Observations: Implications for Cosmology
• The observed ionization rate of the intergalactic medium and the ionizing emissivity at z >= 5: evidence for a photon-starved and extended epoch of reionization
• Galactic Stellar and Substellar Initial Mass Function