| Autor: |
Deparis , Nicolas, Aubert , Dominique, Ocvirk , Pierre, Chardin , Jonathan, Lewis , Joseph |
| Přispěvatelé: |
Observatoire astronomique de Strasbourg ( ObAS ), Université de Strasbourg ( UNISTRA ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) |
| Jazyk: |
angličtina |
| Rok vydání: |
2018 |
| Předmět: |
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| Popis: |
Coupled radiative-hydrodynamics simulations of the epoch of reionization aim at reproducing the propagation of ionization fronts during the transition before the overlap of HII regions. Many of these simulations use moment-based methods to track radiative transfer processes using explicit solvers and are therefore the subject of strict stability conditions regarding the speed of light with a great computational cost. The latter can be reduced by assuming a reduced speed of light and this approximation is now widely used to produce large scale simulations of the reionization. We aim at measuring how ionization fronts propagates in simulations of the epoch of reionization. In particular we aim at distinguishing between the different stages of the fronts progression into the inter-galactic medium. We also investigate how these stages and their properties are impacted by the choice of a reduced speed of light. We introduce a new method to estimate and compare the ionization front speeds based on maps of the reionization redshifts. We apply it to a set of cosmological simulations of the reionization performed with EMMA, with a set of reduced speeds of light and measure the evolution of the ionization fronts speeds during the reionization process. We find that ionization fronts progress via a two-stage process : a first stage at low velocity as they emerge from high density regions and a second later one, just before the overlap, during which front speeds increase, close to the speed of light. We find that a minimal velocity of 0.3c is able to model these two stages without significant impact. Values as low as 0.05c can model the first low velocity stage but limit the acceleration at later times. Smaller values modify the distribution of front speeds at all times. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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