相关论文: Cosmic Reionization on Computers: The Evolution of…

We study the observed cosmic ionizing background as a constraint on the nature of the sources responsible for the reionization of the Universe. In earlier work, we showed that extrapolations of the Ultra-Violet Luminosity Function (LF) of…

Recent evidence supporting reionisation ending at redshift z<6 includes the rapid redshift evolution of the mean free path for Lyman-limit photons through the intergalactic medium at 5<z<6. Here we investigate the mean free path predicted…

Lyman-$\alpha$ (Ly$\alpha$) emitting galaxies are powerful tools to probe the late stages of cosmic reionization. The observed sudden drop in Ly$\alpha$ fraction at $z>6$ is often interpreted as a sign of reionization, since the…

We present an analytical model for cosmological Lyman-limit systems (LLSs) that successfully reproduces the observed evolution of the mean free path (L) of ionizing photons. The evolution of the co-moving mean free path is predominantly a…

We study the spatial fluctuations in the hydrogen ionizing background in the epoch following reionization (z ~ 5--6). The rapid decrease with redshift in the photon mean free path (m.f.p.), combined with the clustering of increasingly rare…

I explore the properties of "dark gaps" - regions in quasar absorption spectra without significant transmission - with several simulations from the Cosmic Reionization On Computers (CROC) project. CROC simulations in largest available boxes…

Quasar absorption spectra measurements suggest that reionization proceeded rapidly, ended late at $z \sim 5.5$, and was followed by a flat ionizing background evolution. Simulations that reproduce this behavior often rely on a fine tuned…

We present the first large-scale, full radiative transfer simulations of the reionization of the intergalactic medium in the presence of Lyman-limit systems (LLSs). To illustrate the impact of LLS opacity, possibly missed by previous…

We present a new method to directly measure the opacity from HI Lyman limit (LL) absorption k_LL along quasar sightlines by the intergalactic medium (IGM). The approach analyzes the average (``stacked'') spectrum of an ensemble of quasars…

Recent measurements of the ionizing photon mean free path ($\lambda_{912}^{\rm mfp}$) at $5 < z < 6$ suggest that the IGM was rapidly evolving at those times. We use radiative transfer simulations to explore the implications for…

The average rate of emission of ionizing radiation per unit volume (or emissivity) in the universe can be calculated as the ratio of the intensity of the ionizing background to the mean free path of ionizing photons. The intensity of the…

We study the evolution of ionization fronts around the first proto-galaxies by using high resolution numerical cosmological (Lambda+CDM model) simulations and Monte Carlo radiative transfer methods. We present the numerical scheme in detail…

Following the completion of cosmic reionization, the mean-free-path of ionizing photons was set by a population of Ly-limit absorbers. As the mean-free-path steadily grew, the intensity of the ionizing background also grew, thus lowering…

We study the properties of self-shielding intergalactic absorption systems and their implications for the ionizing background. We find that cosmological simulations post-processed with detailed radiative transfer calculations generally are…

Quasar absorption lines provide a unique window to the relationship between galaxies and the intergalactic medium during the Epoch of Reionization. In particular, high redshift quasars enable measurements of the neutral hydrogen content of…

Large variations in the effective optical depth of the He II Ly$\alpha$ forest have been observed at $z\gtrsim2.7$, but the physical nature of these variations is uncertain: either the Universe is still undergoing the process of He II…

We investigate the properties of cosmological ionization fronts during the Epoch of Reionization using the CROC simulations. By analyzing reionization timing maps, we characterize ionization front velocities and curvatures and their…

The history of reionization reflects the cumulative injection of ionizing photons by sources and the absorption of ionizing photons by sinks. The latter process is traditionally described in terms of a "clumping factor" which encodes the…

Coupled radiative-hydrodynamics simulations of the epoch of reionization aim to reproduce the propagation of ionization fronts during the transition before the overlap of HII regions. Many of these simulations use moment-based methods to…

The amplitude of the ionizing background that pervades the intergalactic medium (IGM) at the end of the epoch of reionization provides a valuable constraint on the emissivity of the sources which reionized the Universe. While measurements…