The impact of varying inhomogeneous reionization histories on metrics of Ly α opacity
The epoch of hydrogen reionization is complete by z = 5, but its progression at higherredshiftsis uncertain. Measurements of Ly α forest opacity show large scatter at z<6,suggestive ofspatial fluctuationsin neutral fraction, temperature, or ionizing background, either individually or in combinati...
| Autores: | , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2025 |
| País: | España |
| Institución: | Universidad de Sevilla (US) |
| Repositorio: | idUS. Depósito de Investigación de la Universidad de Sevilla |
| OAI Identifier: | oai:idus.us.es:11441/178530 |
| Acceso en línea: | https://hdl.handle.net/11441/178530 https://doi.org/10.1093/mnras/staf616 |
| Access Level: | acceso abierto |
| Palabra clave: | Intergalactic medium Quasars: absorption lines Dark ages Reionization Rirst stars |
| Sumario: | The epoch of hydrogen reionization is complete by z = 5, but its progression at higherredshiftsis uncertain. Measurements of Ly α forest opacity show large scatter at z<6,suggestive ofspatial fluctuationsin neutral fraction, temperature, or ionizing background, either individually or in combination. However, there are degeneracies in the impact of such fluctuations, necessitating careful modelling. We develop a framework for modelling the reionization history and associated temperature fluctuations, with the intention of incorporating ionizing background fluctuations at a later time. We generate several reionization histories using seminumerical code AMBER, and implement them in the Nyx cosmological hydrodynamics code to examine the impact on the evolution of gas within the simulation and the associated metrics of the Ly α forest opacity. We find that the pressure smoothing scale within the intergalactic medium is strongly correlated with the adiabatic index of the temperature–density relation. We find that while models with 20 000 K photoheating at reionization are better able to reproduce the shape of the observed z = 5 1D flux power spectrum than colder ones, they fail to match the highest wavenumbers. The simulated autocorrelation function and optical depth distributions are systematically low and narrow, respectively, compared to the observed values, but are in better agreement when the reionization history is longer in duration, more symmetric in its distribution of reionization redshifts, or if there are remaining neutral regions at z<6. |
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