Related papers: Cosmic Reionization After Planck and Before JWST: …
Recent observations have set the first constraints on the epoch of reionization (EoR), corresponding to the formation epoch of the first luminous objects. Studies of Gunn-Peterson (GP) absorption, and related phenomena, suggest a…
Reionization is an inhomogeneous process, thought to begin in small ionized bubbles of the intergalactic medium (IGM) around overdense regions of galaxies. Recent Lyman-alpha (Ly$\alpha$) studies during the epoch of reionization show…
Thomson optical depth tau measurements from Planck provide new insights into the reionization of the universe. In pursuit of model-independent constraints on the properties of the ionising sources, we determine the empirical evolution of…
We investigate self-shielding of intergalactic hydrogen against ionizing radiation in radiative transfer simulations of cosmic reionization carefully calibrated with Lyman alpha forest data. While self-shielded regions manifest as…
We study the process of cosmic reionization and estimate the ionizing background in the IGM using the Lyman series absorption in the spectra of the four quasars at 5.7<z<6.3 discovered by the SDSS. We derive the evolution of the ionizing…
Reionization is a process whereby hydrogen (and helium) in the Universe is ionized by the radiation from first luminous sources. Theoretically, the importance of the reionization lies in its close coupling with the formation of first cosmic…
We examine the impact of helium reionization on the structure of the intergalactic medium (IGM). We model the reionization using a radiative transfer (RT) code coupled to the combined gravity hydrodynamics code Enzo. Neutral hydrogen and…
In the light of the recent Planck downward revision of the electron scattering optical depth, and of the discovery of a faint AGN population at $z > 4$, we reassess the actual contribution of quasars to cosmic reionization. To this aim, we…
We present a new, on-the-fly photon flux and absorption tracer algorithm designed to directly measure the contribution of different source populations to the metagalactic UV background and to the ionisation fraction of gas in the Universe.…
The timing and duration of the reionization epoch is crucial to the emergence and evolution of structure in the universe. The relative roles that star-forming galaxies, active galactic nuclei and quasars play in contributing to the…
Motivated by the WMAP results indicating an early epoch of reionization, we consider alternative cosmic star formation models which are capable of reionizing the early intergalactic medium. We develop models which include an early burst of…
The time frame in which hydrogen reionization occurred is highly uncertain, but can be constrained by observations of Lyman-alpha (Ly$\alpha$) emission from distant sources. Neutral hydrogen in the intergalactic medium (IGM) attenuates…
Motivated by recent evidence that the epoch of reionization of hydrogen may have ended at a redshift as low as z~6 we consider the detectability of the sources responsible for this reionization. The main idea is that reionization places…
Detections and non-detections of Lyman alpha (Ly$\alpha$) emission from $z>6$ galaxies ($<1$ Gyr after the Big Bang) can be used to measure the timeline of cosmic reionization. Of key interest to measuring reionization's mid-stages, but…
Absorption spectra of high redshift quasars suggest that the reionisation of cosmic hydrogen was complete near z~6. The dominant sources of ionising photons responsible for this reionisation are generally thought to be stars and quasars. In…
Recent JWST observations of Lyman-$\alpha$ emission at $z \sim 11-6$ indicate a rapid reionization of the intergalactic medium within the first $\sim700$ Myr. The required Lyman continuum (LyC) photon budget may naturally arise from the…
The Epoch of Reionization marks the last major phase transition in the early Universe, during which the majority of neutral hydrogen once filling the intergalactic medium was ionized by the first galaxies. The James Webb Space Telescope…
We present a new flexible Bayesian framework for directly inferring the fraction of neutral hydrogen in the intergalactic medium (IGM) during the Epoch of Reionization (EoR, z~6-10) from detections and non-detections of Lyman Alpha…
The temporal evolution of the ionizing UV background radiation field at high redshift provides a probe of the evolution of the early star formation rate. By comparing the observed levels of absorption in the highest redshift quasar spectra…
The escape fraction of Lyman-continuum (LyC) photons ($f_{esc}$) is a key parameter for determining the sources of cosmic reionization at $z\geq 6$. At these redshifts, owing to the opacity of the intergalactic medium, the LyC emission…