Related papers: Fluctuations in the Ionizing Background During and…
The lifetime of quasars is fundamental for understanding the growth of supermassive black holes, and is an important ingredient in models of the reionization of the intergalactic medium. However, despite various attempts to determine quasar…
The ionisation structure of the Intergalactic Medium (IGM) during reionisation is sensitive to the unknown galaxy formation physics that prevailed at that time. This structure introduces non-Gaussian statistics into the redshifted 21 cm…
The neutral hydrogen (HI) and its 21 cm line are promising probes to the reionization process of the intergalactic medium (IGM). To use this probe effectively, it is imperative to have a good understanding on how the neutral hydrogen traces…
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 implement a treatment of Helium {\sc ii} absorption and re-emission into the \TD cosmological simulations to study its impact on the metagalactic ultraviolet background (UVB) in three dimensions. By comparing simulations with and without…
Recent observations of z~6 quasars and the cosmic microwave background imply a complex history to cosmic reionization. Such a history requires some form of feedback to extend reionization over a long time interval, but the nature of the…
The reionization of intergalactic hydrogen has received intense theoretical scrutiny over the past two decades. Here, we approach the process formally as a percolation process and phase transition. Using semi-numeric simulations, we…
We present new measurements of the intensity of the ionizing ultraviolet background and the global emissivity of ionizing photons over 2 < z < 5. Our results are based on a suite of updated measurements of physical properties of the…
The reionization epoch concludes when ionizing photons reach every corner of the Universe. Reionization has generally been assumed to be limited primarily by the rate at which galaxies produce ionizing photons, but the recent measurement of…
We present a reanalysis of the HeII Lyman alpha absorption towards the quasars HS1700+6416 and HE2347-4342 using new high S/N, optical observations. An alternative analysis method is applied, which fits the high quality, optical HI data…
The thermal history of the intergalactic medium (IGM) after reionization is to a large extent determined by photoheating. Here we demonstrate that calculations of the photoheating rate which neglect radiative transfer effects substantially…
The first sources of ionizing radiation to condense out of the dark and neutral IGM sent ionization fronts sweeping outward through their surroundings, overtaking other condensed objects and photoevaporating them. This feedback effect of…
We consider the effects of inhomogeneous reionization on the distribution of galaxies at high redshifts. Modulation of the formation process of the ionizing sources by large scale density modes makes reionization inhomogeneous and…
The 21cm background from the epoch of reionization is a promising cosmological probe: line-of-sight velocity fluctuations distort redshift, so brightness fluctuations in Fourier space depend upon angle, which linear theory shows can…
One of the most sought-after signatures of reionization is a rapid increase in the ionizing background (usually measured through the Lyman-alpha optical depth toward distant quasars). Conventional wisdom associates this with the "overlap"…
We combine high resolution hydrodynamical simulations with an intermediate resolution, dark matter only simulation and an analytical model for the growth of ionized regions to estimate the large scale distribution and redshift evolution of…
Early photoionization of the intergalactic medium is discussed in a nearly model-independent way, in order to investigate whether early structures corresponding to rare Gaussian peaks in a CDM model can photoionize the intergalactic medium…
We discuss the potential of using the HeI 584 A forest to detect and study HeII reionization. Significant 584 A absorption is expected from intergalactic HeII regions, whereas there should be no detectable absorption from low density gas in…
We show that the process of photoionizing a gas of atomic hydrogen and helium by line radiation whose energy is slightly above the helium single-ionization threshold is unstable if the helium fraction by number is less than approximately…
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…