Related papers: Lyman-alpha Damping Wing Constraints on Inhomogene…
Neutral gas in galaxies during the Epoch of Reionisation regulates star formation, dust growth, and the escape of ionising photons, making it a key ingredient in understanding both galaxy assembly and reionisation. Yet, direct constraints…
We derive the distribution of neutral and ionized gas in high redshift clouds which are optically thick to hydrogen ionizing radiation, using published data on Lyman-limit and Damped Lyman-alpha absorption systems in the redshift range 1.75…
We develop an analytic approach to study inhomogeneous reionization on large scales by solving the equations of ionization balance and radiative transfer to first order in perturbations. Given the spatial distribution and spectrum of the…
The temperature of the diffuse, photo-heated intergalactic medium (IGM) depends on its reionization history because the thermal time scales are long. The widths of the hydrogen Lyman-alpha absorption lines seen in the spectra of distant…
Local variations in the intergalactic medium (IGM) neutral hydrogen fraction will affect the Ly-$\alpha$ absorption signature of protoclusters identified in tomographic surveys. Using the IllustrisTNG simulations, we investigate how the AGN…
Absorption spectra of high redshift quasars exhibit an increasingly thick Ly-alpha forest towards z~6. However, the interpretation of these spectra is complicated by the fact that the Ly-alpha optical depth is already large for neutral…
Observations of the Lyman-alpha (Ly-$\alpha$) forest may allow reionization to complete as late as $z \sim 5.5$, provided the ionization state of the intergalactic medium (IGM) is sufficiently inhomogeneous at these redshifts. In this case,…
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…
We use synthetic sightlines drawn through snapshots of the Technicolor Dawn simulations to explore how the statistics of neutral oxygen OI absorbers respond to hydrogen reionization. The ionization state of the circumgalactic medium (CGM)…
The sky-averaged (global) 21-cm signal is a powerful probe of the intergalactic medium (IGM) prior to the completion of reionization. However, it has so far been unclear that even in the best case scenario, in which the signal is accurately…
Measurements of the intergalactic medium (IGM) temperature provide a potentially powerful constraint on the reionisation history due to the thermal imprint left by the photo-ionisation of neutral hydrogen. However, until recently IGM…
Correlations measured in three dimensions in the Lyman-alpha forest are contaminated by the presence of the damping wings of high column density (HCD) absorbing systems of neutral hydrogen (HI; having column densities $N(\mathrm{HI}) >…
Measurement of the red damping wing of neutral hydrogen in quasar spectra provides a probe of the epoch of reionization in the early Universe. Such quantification requires precise and unbiased estimates of the intrinsic continua near…
High-redshift quasars (z >~ 6) drive ionization fronts into the intergalactic medium (IGM). If the thickness of the front can be measured, it can provide a novel constraint on the ionizing spectral energy distribution (SED). Here we follow…
Understanding the sources responsible for reionizing the Universe is a key goal of observational cosmology. A discrepancy has existed between the metagalactic hydrogen ionization rate, Gamma_HI, predicted by early hydrodynamical simulations…
Detecting neutral hydrogen structures in the intergalactic medium (IGM) during cosmic reionization via absorption (21 cm forest) against a background radiation is considered independent and complementary to the three-dimensional tomography…
We explore the possibility of detecting HI 21cm absorption by the neutral intergalactic medium (IGM) toward very high redshift radio sources. The epoch considered is between the time when the first ionizing sources form and when the bulk of…
We present a survey of six low to moderate redshift quasars with Chandra and XMM-Newton. The primary goal is to search for the narrow X-ray absorption lines produced by highly ionized metals in the Warm-Hot Intergalactic Medium. All the…
Cosmic reionization is expected to be complex, extended and very inhomogeneous. Existing constraints at z~6 on the volume-averaged neutral hydrogen fraction, <x_HI>, are highly model-dependent and controversial. Constraints at z<6,…
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…