On the evolution of the H i column density distribution in cosmological simulations

By A. Rahmati, A. Pawlik, Milan Raivcevi'c, Joop Schaye. 2012

342 citations recorded by the source corpus.

We use a set of cosmological simulations combined with radiative transfer calculations to investigate the distribution of neutral hydrogen in the post-reionization Universe. We assess the contributions from the metagalactic ionizing background, collisional ionization and diffuse recombination radiation to the total ionization rate at redshifts z = 0 5. We find that the densities above which hydrogen self-shielding becomes important are consistent with analytic calculations and previous work. However, because of diffuse recombination radiation, whose intensity peaks at the same density, the transition between highly ionized and self-shielded regions is smoother than what is usually assumed. We provide fitting functions to the simulated photoionization rate as a function of density and show that post-processing simulations with the fitted rates yields results that are in excellent agreement with the original radiative transfer calculations. The predicted neutral hydrogen column density distributions agree very well with the observations. In particular, the simulations reproduce the remarkable lack of evolution in the column density distribution of Lyman limit and weak damped Lyα systems below z = 3. The evolution of the low column density end is affected by the increasing importance of collisional ionization with decreasing redshift. On the other hand, the simulations predict the abundance of strong damped Lyα systems to broadly track the cosmic star formation rate density.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/fa3e56e52e8f2069a0fa722aff73697f7c095073

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Citations in the corpus

MUFASA: Galaxy Formation Simulations With Meshless Hydrodynamics (2016, methodology): “We compute the self-shielded cold gas fraction for each gas element using the prescription described in Rahmati et al. (2013), which parameterises the effective strength of the photo-ionising background impinging on gas as a function of density and redshift.”
First results from the IllustrisTNG simulations: the galaxy colour bimodality (2017, methodology): “…hydrogen fraction of each gas cell is computed during the simulation using the atomic network of Katz et al. (1996) with the time variable though spatially uniform ionizing UV background of Faucher-Giguère et al. (2009) given the density-based self shielding prescription of Rahmati et al. (2013).”
The Giant Gemini GMOS survey of zem > 4.4 quasars – I. Measuring the mean free path across cosmic time (2014, background): “…filaments, the cosmic web), consistent with current numerical results exploring the frequency distribution of H I gas (Altay et al. 2011; Fumagalli et al. 2011; McQuinn et al. 2011; Rahmati et al. 2013) and recent analysis of the cross-correlation between LLSs and quasars (Prochaska et al. 2013b).”
The EAGLE project: Simulating the evolution and assembly of galaxies and their environments (2014, methodology): “More recently, simulations that have been reprocessed using radiative transfer of ionizing radiation have succeeded in matching key properties of the high-column density H i absorbers (e.g. Pontzen et al. 2008; Altay et al. 2011; McQuinn et al. 2011; Rahmati et al. 2013a).”
Cosmological simulations of the circumgalactic medium with 1 kpc resolution: enhanced H i column densities (2018, methodology): “The correction due to self-shielding as given in Rahmati et al. (2013) was derived from simulations with much lower resolution and may not be applicable to the small clouds we can resolve here.”
Ingredients for 21 cm Intensity Mapping (2018, methodology): “In other words, we are neglecting the contribution of ionizing photons from, e.g., local sources (Miralda-Escudé 2005; Schaye 2006; Rahmati et al. 2013b) or X-ray heating from the intracluster medium (Kannan et al. 2015).”
The EAGLE simulations of galaxy formation: the importance of the hydrodynamics scheme (2015, methodology): “With the help of careful simulations using radiative transfer, Rahmati et al. (2013) showed that cold (T < 104.5 K) and dense (nH > 0.01 cm−3) gas is a good proxy for H I gas.”
simba: Cosmological simulations with black hole growth and feedback (2019, background): “Second, it includes selfshielding self-consistently during the simulation run, based on the Rahmati et al. (2013) prescription in which the ionising background strength is attenuated depending (primarily) on gas density.”
A model for cosmological simulations of galaxy formation physics: multi-epoch validation (2013, methodology): “Our implementation is derived from the results of radiation transfer simulations by Rahmati et al. (2013), who postprocessed cosmological simulations using the radiation transfer code TRAPHIC (Pawlik & Schaye 2008, 2011), and quantified the self-shielding of the intergalactic gas as a function of…”
The impact of star formation feedback on the circumgalactic medium (2016, methodology): “At z = 0 the density above which self-shielding becomes important is nSSh ≈ 3 × 10−3cm−3 (Rahmati et al. 2013).”
The Illustris simulation: the evolving population of black holes across cosmic time (2014, background): “…primordial and metal-line cooling in the presence of time dependent UV background (Faucher-Giguère et al. 2009) including gas self-shielding (Rahmati et al. 2013), where the metals are naturally advected with the fluid flow; a sub-grid model for star formation and associated supernovae…”
Can the intergalactic medium cause a rapid drop in Lyα emission at z > 6? (2014, background): “…the self-shielding of the gas through a densitydependent photoionization rate, obtained by an empirical fit to radiative transfer simulations (Rahmati et al. 2013): Γss Γ = 0.98× [ 1 + ( ∆ ∆ss )1.64]−2.28 + + 0.02× [ 1 + ∆ ∆ss ]−0.84 (4) where ∆ss is the overdensity above which the gas…”
An updated analytic model for attenuation by the intergalactic medium (2014, background): “Indeed, the latest cosmological radiation hydrodynamics simulations show that the self-shielding of the optically thick absorbers is the mechanism producing the break (Altay et al. 2011; Rahmati et al. 2013).”
Neutral hydrogen in galaxy haloes at the peak of the cosmic star formation history (2014, methodology): “Gas in these low-mass halos is particularly sensitive to heating by the ionizing background (e.g., Efstathiou 1992; Thoul & Weinberg 1996; FaucherGiguère et al. 2011) and to the effects of stellar feedback (e.g., Dekel & Silk 1986).”
Inhomogeneous recombinations during cosmic reionization (2014, methodology): “(iv) Using the local photoionization rate, we compute the neutral fraction at each overdensity, assuming ionization equilibrium and a self-shielding prescription (Schaye 2001; Rahmati et al. 2013).”
GRACKLE: a chemistry and cooling library for astrophysics (2016, methodology): “!) that is generally found to be a reasonable approximation (Osterbrock & Ferland 2006; McQuinn & Switzer 2010; Friedrich et al. 2012; Rahmati et al. 2013).”
The ESO UVES advanced data products quasar sample: II. Cosmological evolution of the neutral gas mass density (2013, methodology): “The Altay et al. (2011) model provides a reasonable representation of the data down to Lyα forest range at z ∼ 3 (see also van de Voort et al. 2012; Rahmati et al. 2013a; Rahmati et al. 2013b).”
Lyα Emitting Galaxies as a Probe of Reionisation (2014, background): “The abundance of LLSs increases (weakly) with redshift at z > 3 (e.g. Rahmati et al. 2013), and may strongly affect the IGM opacity at z > 6 (Bolton & Haehnelt 2013, but see Mesinger et al. 2014).”
Physical Models of Galaxy Formation in a Cosmological Framework (2014, methodology): “In addition, SAMs and numerical simulations are being used to study the nature of H i seen in absorption (Lyman-limit and Damped Lyman-α systems), and its connection with galaxies identified in emission (Berry et al. 2014, Bird et al. 2014, Rahmati et al. 2013, Rahmati & Schaye 2014).”