The short ionizing photon mean free path at z=6 in Cosmic Dawn III, a new fully-coupled radiation-hydrodynamical simulation of the Epoch of Reionization

Abstract

Recent determinations of the mean free path of ionising photons (mfp) in the intergalactic medium (IGM) at $\mathrm{z}=6$ are lower than many theoretical predictions. To gain insight into this issue, we investigate the evolution of the mfp in our new massive fully coupled radiation hydrodynamics cosmological simulation of reionization: Cosmic Dawn III (CoDaIII). CoDaIII's scale ($94^3\mathrm{cMp}{\mathrm{c}}^3$) and resolution ($8192^3$ grid) make it particularly suitable to study the evolution of the IGM during Reionization. The simulation was performed with RAMSES-CUDATON on Summit, and used 131072 processors coupled to 24576 GPUs, making it the largest Reionization simulation, and largest RAMSES simulation ever performed. A superior agreement with global constraints on Reionization is obtained in CoDaIII over CoDaII especially for the evolution of the neutral hydrogen fraction and the cosmic photo-ionization rate, thanks to an improved calibration, later end of reionization ($\mathrm{z}=5.6$), and higher spatial resolution. Analyzing the mfp, we find that CoDaIII reproduces the most recent observations very well, from $\mathrm{z}=6$ to $\mathrm{z}=4.6$. We show that the distribution of the mfp in CoDaIII is bimodal, with short (neutral) and long (ionized) mfp modes, respectively, due to the patchiness of reionization and the co-existence of neutral versus ionized regions during Reionization. The neutral mode peaks at sub-kpc to kpc scales of mfp, while the ionized mode peak evolves from $0.1Mpc/h$ at $\mathrm{z}=7$ to $\sim 10$ Mpc/h at $\mathrm{z}=5.2$. Computing the mfp as the average of the ionized mode provides the best match to the recent observational determinations. The distribution reduces to a single neutral (ionized) mode at $\mathrm{z}>13$ ($\mathrm{z}<5$).

arXiv commentSubmitted to MNRAS Accepted 2022 August 08. Received 2022 August 05; in original form 2022 February 11

References in corpus (56)

• Planck 2013 results. XVI. Cosmological parameters
• Cosmological Hydrodynamics with Adaptive Mesh Refinement: a new high resolution code called RAMSES
• A luminous quasar at a redshift of z = 7.085
• Constraining the Evolution of the Ionizing Background and the Epoch of Reionization with z ~ 6 Quasars II: A Sample of 19 Quasars
• An 800-million-solar-mass black hole in a significantly neutral Universe at redshift 7.5
• Statistics of 207 Lya Emitters at a Redshift Near 7: Constraints on Reionization and Galaxy Formation Models
• Reevaluating Old Stellar Populations
• Model-independent evidence in favor of an end to reionization by z~6
• Evidence of patchy hydrogen reionization from an extreme Ly$\alpha$ trough below redshift six
• Spectroscopic Confirmation of Three z-Dropout Galaxies at z = 6.844 - 7.213: Demographics of Lyman-Alpha Emission in z ~ 7 Galaxies
• The Universe is Reionizing at z~7: Bayesian Inference of the IGM Neutral Fraction Using Ly$\alpha$ Emission from Galaxies
• New Measurements of the Ionizing Ultraviolet Background over 2 < z < 5 and Implications for Hydrogen Reionization
• Planck intermediate results. LVII. Joint Planck LFI and HFI data processing
• Hydrogen reionisation ends by $z=5.3$: Lyman-$\alpha$ optical depth measured by the XQR-30 sample
• On the onset of galactic winds in quiescent star forming galaxies
• Line Emitting Galaxies Beyond a Redshift of 7: An Improved Method for Estimating the Evolving Neutrality of the Intergalactic Medium
• New observations of z~7 galaxies: evidence for a patchy reionization
• Large Lyman-alpha opacity fluctuations and low CMB tau in models of late reionization with large islands of neutral hydrogen extending to z<5.5
• Introducing the THESAN project: radiation-magnetohydrodynamic simulations of the epoch of reionization
• Cosmic Dawn (CoDa): the First Radiation-Hydrodynamics Simulation of Reionization and Galaxy Formation in the Local Universe
• The Giant Gemini GMOS survey of z>4.4 quasars - I. Measuring the mean free path across cosmic time
• Rapid Decline of Lyman-alpha Emission Toward the Reionization Era
• Constraining the neutral fraction of hydrogen in the IGM at redshift 7.5
• Measurements of the UV background at 4.6 < z < 6.4 using the quasar proximity effect
• Long troughs in the Lyman-$\alpha$ forest below redshift 6 due to islands of neutral hydrogen
• New Constraints on IGM Thermal Evolution from the Lyα Forest Power Spectrum
• The mean free path of ionizing photons at 5 < z < 6: evidence for rapid evolution near reionization
• A radiative transfer scheme for cosmological reionization based on a local Eddington tensor
• Revealing reionization with the thermal history of the intergalactic medium: new constraints from the Lyman-$\alpha$ flux power spectrum
• Texas Spectroscopic Search for Ly$\alpha$ Emission at the End of Reionization III. the Ly$\alpha$ Equivalent-width Distribution and Ionized Structures at $z>7$
• Large Fluctuations in the High-Redshift Metagalactic Ionizing Background
• Evidence of Gunn-Peterson damping wings in high-z quasar spectra: strengthening the case for incomplete reionization
• Probing the thermal state of the intergalactic medium at $z>5$ with the transmission spikes in high-resolution Ly$\alpha$ forest spectra
• The THESAN project: properties of the intergalactic medium and its connection to Reionization-era galaxies
• AREPO-RT: Radiation hydrodynamics on a moving mesh
• Reionization simulations powered by GPUs I: the structure of the Ultraviolet radiation field
• The Global History of Reionisation
• Hydrodynamic Response of the Intergalactic Medium to Reionization
• A short mean free path at $z=6$ favors late and rapid reionization by faint galaxies
• Reionization history constraints from neural network based predictions of high-redshift quasar continua
• Suppression of Star Formation in Low-Mass Galaxies Caused by the Reionization of their Local Neighborhood
• The Low-redshift Lyman-continuum Survey: [S II]-deficiency and the leakage of ionizing radiation
• Lyman-alpha opacities at z=4-6 require low mass, radiatively-suppressed galaxies to drive cosmic reionization
• Impact of the reduced speed of light approximation on ionization front velocities in cosmological simulations of the epoch of reionization
• The Predicament of Absorption-Dominated Reionization: Increased Demands on Ionizing Sources
• Impact of the reduced speed of light approximation on the post-overlap neutral hydrogen fraction in numerical simulations of the epoch of reionization
• Reionization of the Local Group of Galaxies
• High Precision Analyses of Lyman alpha Damping Wing of Gamma-Ray Bursts in the Reionization Era: On the Controversial Results from GRB 130606A at z = 5.91
• Models of the Cosmological 21 cm Signal from the Epoch of Reionization Calibrated with Lyman-alpha and CMB Data
• Galaxy clusters in simulations of the local Universe: a matter of constraints
• On the Proper Use of the Reduced Speed of Light Approximation
• The mean free path of hydrogen ionizing photons during the epoch of reionization
• The reionization of galactic satellite populations
• High resolution simulations of the reionization of an isolated Milky Way - M31 galaxy pair
• Cosmic Reionization May Still Have Started Early and Ended Late: Confronting Early Onset with CMB Anisotropy and 21 cm Global Signals
• Reionization of the Milky Way, M31, and their satellites I: reionization history and star formation

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• Reionization in HESTIA: Studying reionization in the LG through zoom simulations