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
Year: 2022
Type: article
Abstract: ABSTRACT Recent determinations of the mean free path of ionizing photons (mfp) in the intergalactic medium (IGM) at z = 6 are lower than many theoretical predictions. In order to gain insight, we investigate the evolution of the mfp in our new massive fully coupled radiation-hydrodynamics cosmological simulation of reionization: Cosmic Dawn III (CoDa III). CoDa III’s scale ($\rm 94^3 \, cMpc^3$) and resolution ($\rm 8192^3$ grid) make it particularly suitable to study the IGM during reionization. The simulation was performed with ramses-cudaton on Summit, and used 13 1072 processors coupled to 24 576 GPUs, making it the largest reionization simulation, and largest ever ramses simulation. A superior agreement with global constraints on reionization is obtained in CoDa III over Cosmic Dawn II (CoDa II), especially for the evolution of the neutral hydrogen fraction and the cosmic photoionization rate, thanks to an improved calibration, later end of reionization (z = 5.6), and higher spatial resolution. Analysing the mfp, we find that CoDa III reproduces the most recent observations very well, from z = 6 to z = 4.6. We show that the distribution of the mfp in CoDa III is bimodal, with short (neutral) and long (ionized) mfp modes, due to the patchiness of reionization and the coexistence 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 0.1 Mpc h−1 at z = 7 to ∼10 Mpc h−1 at 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 z > 13 (z < 5).
Institutions: Heidelberg University, Max Planck Institute for Astronomy, Centre National de la Recherche Scientifique, Observatoire astronomique de Strasbourg, Université de Strasbourg, Université Paris-Saclay, Leibniz Institute for Astrophysics Potsdam, Institut d'Astrophysique Spatiale, Institut d'Astrophysique de Paris, Université Pierre-et-Marie-Curie, University of Sussex, The University of Texas at Austin, University of Zurich, Institute for Theoretical Physics, Universidad Autónoma de Madrid, Université Paris Cité, Université Paris Sciences et Lettres, Observatoire de Paris, Laboratoire Univers et Théories, Chosun University, Lawrence Berkeley National Laboratory, Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo, University of California, Berkeley
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $2,858
Funders: International Trachoma Initiative, California Department of Fish and Game, Neurosciences Research Foundation, Deutsche Forschungsgemeinschaft, Agence Nationale de la Recherche, Ministry of Education, Culture, Sports, Science and Technology, Federación Española de Enfermedades Raras, Gujarat Cancer Society, South East Physics Network, Gauss Centre for Supercomputing, Science and Technology Facilities Council, Leibniz-Gemeinschaft, Japan Society for the Promotion of Science, Leibniz-Rechenzentrum, Oak Ridge National Laboratory
Awards: G1014665743, University of Sussex Astronomy Consolidated Grant 2020-2023, G1620761618, Can Baryon-Dark Matter Streaming Motion Explain Supermassive Blackholes in the Early Universe?, G2107459524, G3299690580, G4279081818, G5073819773, LOcal Clusters And super cLuster In sZ: Adding Therma, kInetic and relativistic cOrrectioNs, EXC 2181: STRUKTUREN: Emergenz in Natur, Mathematik und komplexen Daten, G8341306918, Astrophysics and Cosmology at the University of Sussex (2011-2016)
OpenAlex ID: W4293811315