On merger bias and the clustering of quasars (2009)
Bonoli, Silvia, Shankar, Francesco, White, Simon, Springel, Volker, Wyithe, Stuart
We use the large catalogues of haloes available for the Millennium Simulation to test whether recently merged haloes exhibit stronger large-scale clustering than other haloes of the same mass. This...
The Halo Occupation Distribution of HI Galaxies (2009)
Wyithe, Stuart, Brown, Michael J. I., Zwaan, Martin A., Meyer, Martin J.
We perform an analysis of the spatial clustering properties of HI selected galaxies from the HI Parkes All Sky Survey (HIPASS) using the formalism of the halo occupation distribution (HOD). The...
Wyithe, Stuart, Hopkins, Andrew M., Kistler, Matthew D., Yuksel, Hasan, Beacom, John F.
The fraction of ionizing photons that escape their host galaxies and so are able to ionize hydrogen in the inter-galactic medium (IGM) is a critical parameter in analyses of the reionization era and...
21 cm Intensity Mapping (2009)
Peterson, Jeffrey B., Aleksan, Roy, Ansari, Reza, Bandura, Kevin, Bond, Dick, Bunton, John, ...
Using the 21 cm line, observed all-sky and across the redshift range from 0 to 5, the large scale structure of the Universe can be mapped in three dimensions. This can be accomplished by studying...
Cosmological Constraints from 21cm Surveys After Reionization (2008)
Visbal, Eli, Loeb, Abraham, Wyithe, Stuart
21cm emission from residual neutral hydrogen after the epoch of reionization can be used to trace the cosmological power spectrum of density fluctuations. Using a Fisher matrix formulation, we...
Evidence for Merger-Driven Activity in the Clustering of High Redshift Quasars (2008)
Recently, a very large clustering length has been measured for quasars at a redshift of z~4. In combination with the observed quasar luminosity function we assess the implications of this clustering...
Dijkstra, Mark, Haiman, Zoltan, Mesinger, Andrei, Wyithe, Stuart
The earliest generation of stars and black holes must have established an early 'Lyman-Werner' background (LWB) at high redshift, prior to the epoch of reionization. Because of the long mean free...
Modification of the 21-cm power spectrum by X-rays during the epoch of reionisation (2008)
Warszawski, Lila, Geil, Paul M., Wyithe, Stuart
We incorporate a contribution to reionization from X-rays within analytic and semi-numerical simulations of the 21-cm signal arising from neutral hydrogen during the epoch of reionization. We explore...
The Impact of HI in Galaxies on 21-cm Intensity Fluctuations During the Reionisation Epoch (2008)
Wyithe, Stuart, Warszawski, Lila, Geil, Paul M., Oh, S. Peng
We investigate the impact of neutral hydrogen (HI) in galaxies on the statistics of 21-cm fluctuations using analytic and semi-numerical modelling. Following the reionisation of hydrogen the HI...
The 21cm Power Spectrum After Reionization (2008)
We discuss the 21cm power spectrum (PS) following the completion of reionization. In contrast to the reionization era, this PS is proportional to the PS of mass density fluctuations, with only a...
The escape fraction of ionizing photons from high redshift galaxies (2008)
Srbinovsky, Jhan, Wyithe, Stuart
The fraction of ionizing photons which escape their host galaxy and so are able to ionize hydrogen in the inter-galactic medium (IGM) is a critical parameter in studies of the reionization era and...
Geil, Paul. M., Wyithe, Stuart, Petrovic, Nada, Oh, Peng
We assess the impact of Galactic synchrotron foreground removal on the observation of high-redshift quasar HII regions in redshifted 21-cm emission. We consider the case where a quasar is observed in...
Observations of damped Ly-alpha absorbers (DLA) indicate that the fraction of hydrogen in its neutral form (HI) is significant by mass at all redshifts. This gas represents the reservoir of material...
Redshifted 21cm Observations of High Redshift Quasar Proximity Zones (2008)
The introduction of low-frequency radio arrays is expected to revolutionize the study of the reionization epoch. Observation of the contrast in redshifted 21cm emission between a large HII region and...
Measurements of the 21cm line emission by residual cosmic hydrogen after reionization can be used to trace the power spectrum of density perturbations through a significant fraction of the observable...
Baryonic Acoustic Oscillations in 21cm Emission: A Probe of Dark Energy out to High Redshifts (2007)
Wyithe, Stuart, Loeb, Abraham, Geil, Paul
Low-frequency observatories are currently being constructed with the goal of detecting redshifted 21cm emission from the epoch of reionization. These observatories will also be able to detect...
The Impact of a Percolating IGM on Redshifted 21 cm Observations of Quasar HII Regions (2007)
We assess the impact of inhomogeneous reionization on detection of HII regions surrounding luminous high redshift quasars using planned low frequency radio telescopes. Our approach is to implement a...
Fluctuations in 21cm Emission After Reionization (2007)
The fluctuations in the emission of redshifted 21cm photons from neutral inter-galactic hydrogen will provide an unprecedented probe of the reionization era. Conventional wisdom assumes that this...
Reionization Bias in High Redshift Quasar Near-Zones (2007)
Wyithe, Stuart, Bolton, James, Haehnelt, Martin
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...
The Imprint of Cosmic Reionization on Galaxy Clustering (2007)
We consider the effect of reionization on the clustering properties of galaxy samples at intermediate redshifts (z~0.3-5.5). Current models for the reionization of intergalactic hydrogen predict that...
A search for H I 21 cm absorption toward the highest redshift (z~5.2) radio-loud objects (2007)
Carilli, C.L., Wang, Ran, Van Hoven, M.B., Dwarakanath, K.S., Chengalur, Jayaram N., Wyithe, Stuart
Restricted Access. An open-access version is available at arXiv.org (one of the alternative locations)
The Correlation Between Star Formation and 21cm Emission During the Reionization Epoch (2007)
Wyithe, Stuart, Loeb, Avi, Schmidt, Brian
Reionization is thought to be dominated by low mass galaxies, while direct observations of resolved galaxies probe only the most massive, rarest objects. The cross-correlation between fluctuations in...
Very Massive Stars in High-Redshift Galaxies (2007)
Dijkstra, Mark, Wyithe, Stuart
A significant fraction of Lyman Alpha (Lya) emitting galaxies (LAEs) at z> 5.7 have rest-frame equivalent widths (EW) greater than ~100 Angstrom. However only a small fraction of the Lya flux...
Wyithe, Stuart, Morales, Miguel
Spatial dependence in the statistics of redshifted 21cm fluctuations promises to provide the most powerful probe of the reionisation epoch. In this paper we consider the second and third moments of...
The Impact of The IGM on High-Redshift Lyman Alpha Emission Lines (2007)
Dijkstra, Mark, Lidz, Adam, Wyithe, Stuart
We calculate the impact of the intergalactic medium (IGM) on the observed Lyman alpha lines (hereafter Lya) emitted by galaxies in an ionised IGM at z>4. Our model accounts for gas clumping in the...
Luminosity Functions of Lyman Alpha Emitting Galaxies and Cosmic Reionization of Hydrogen (2006)
Dijkstra, Mark, Wyithe, Stuart, Haiman, Zoltan
Recent observations imply that the observed number counts of Lya Emitters (LAEs) evolved significantly between z=5.7 and z=6.5. It has been suggested that this was due to a rapid evolution in the...
Constraining the Quasar Contribution to the Reionisation of Cosmic Hydrogen (2006)
Srbinovsky, Jhan, Wyithe, Stuart
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...
The correlation between the distribution of galaxies and 21cm emission at high redshifts (2006)
Deep surveys have recently discovered galaxies at the tail end of the epoch of reionization. In the near future, these discoveries will be complemented by a new generation of low-frequency radio...
Smooth Boundaries to Cosmological HII Regions from Galaxy Clustering (2006)
The HII regions around quasars and galaxies at redshifts beyond the epoch of reionisation will provide prime targets for upcoming 21cm campaigns using a new generation of low-frequency radio...
Lyman Alpha Constraints on Very Low Luminosity AGN (2006)
Dijkstra, Mark, Wyithe, Stuart
Recent surveys have detected Lya emission from z=4.5-6.5 at luminosities as low as 10^41 erg/s. There is good evidence that low numbers of AGN are among observed faint Lya emitters. Combining these...
Dwarf Galaxy Formation Was Suppressed By Cosmic Reionization (2006)
A large number of faint galaxies, born less than a billion years after the big bang, have recently been discovered. The fluctuations in the distribution of these galaxies contributed to a scatter in...
Wyithe, Stuart, Padmanabhan, T.
In the local universe, the masses of Super-Massive Black-Holes (SMBH) appear to correlate with the physical properties of their hosts, including the mass of the dark-matter halo. Using these clues as...
Population-III (Pop-III) starformation (SF) is thought to be quenched when the metallicity of the star-forming gas reaches a critical level. At high z, when the general intergalactic medium (IGM) was...
Cosmic Variance In the Transparency of the Intergalactic Medium After Reionization (2005)
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...
Prospects for Redshifted 21-cm observations of quasar HII regions (2005)
Wyithe, Stuart, Loeb, Abraham, Barnes, David
The introduction of low-frequency radio arrays over the coming decade is expected to revolutionize the study of the reionization epoch. Observation of the contrast in redshifted 21cm emission between...
We demonstrate that a log-linear relation does not provide an adequate description of the correlation between the masses of Super-Massive Black-Holes (SMBH, M_bh) and the velocity dispersions of...
Wyithe, Stuart, Padmanabhan, T.
In the local universe, the masses of Super-Massive Black-Holes (SMBH) appear to correlate with physical properties of their hosts, including the mass of the dark-matter halos. At higher redshifts, we...
Wyithe, Stuart, Loeb, Abraham, Carilli, Chris
We analyze the evolution of HII regions around the seven known SDSS quasars at z>6. The comparison between observed and model radii of the HII regions generated by these quasars individually,...
A Size of ~10 Mpc for the Ionized Bubbles at the End of Cosmic Reionization (2004)
The first galaxies to appear in the universe at redshifts z>20 created ionized bubbles in the intergalactic medium of neutral hydrogen left over from the Big-Bang. It is thought that the ionized...
The discovery of Lyman-alpha emission from galaxies at redshifts beyond z~6.5 should not be naively interpreted as implying that the intergalactic medium (IGM) had been reionized at higher redsifts....
Calibrating the Galaxy Halo - Black Hole Relation Based on the Clustering of Quasars (2004)
The observed number counts of quasars may be explained either by long-lived activity within rare massive hosts, or by short-lived activity within smaller, more common hosts. It has been argued that...
Redshifted 21cm Signatures Around the Highest Redshift Quasars (2004)
The Ly-alpha absorption spectrum of the highest redshift quasars indicates that they are surrounded by giant HII regions, a few Mpc in size. The neutral gas around these HII regions should emit 21cm...
Cosmic Hydrogen Was Significantly Neutral a Billion Years After the Big Bang (2004)
The ionization fraction of cosmic hydrogen, left over from the big bang, provides crucial fossil evidence for when the first stars and quasar black holes formed in the infant universe. Spectra of the...
The comoving mass density of massive black hole (MBH) remnants from pre-galactic star formation could have been similar in magnitude to the mass-density of supermassive black holes (SMBHs) in the...
We place a limit on the logarithmic slope of the luminous quasar luminosity function at z~6 of beta>-3.0 (90%) using gravitational lensing constraints to build on the limit of beta>-3.3 (90%) derived...
We postulate that supermassive black-holes grow in the centers of galaxies until they unbind the galactic gas that feeds them. We show that the corresponding self-regulation condition yields a...
Was the Universe Reionized by Massive Population-III Stars? (2003)
The WMAP satellite has measured a large optical depth to electron scattering after cosmological recombination of 0.17+-0.04, implying significant reionization of the primordial gas only ~200 million...
Reionization of Hydrogen and Helium by Early Stars and Quasars (2002)
We compute the reionization histories of hydrogen and helium due to the ionizing radiation fields produced by stars and quasars. For the quasars we use a model based on halo-merger rates that...
A Physical Model for the Luminosity Function of High-Redshift Quasars (2002)
We provide a simple theoretical model for the quasar luminosity function at high redshifts that naturally reproduces the statistical properties of the luminous SDSS quasar sample at redshifts z~4.3...
Intensive monitoring campaigns have recently attempted to measure the time delays between multiple images of gravitational lenses. Some of the resulting light-curves show puzzling low-level, rapid...
Gravitational Lensing of the SDSS High-Redshift Quasars (2002)
We predict the effects of gravitational lensing on the color-selected flux-limited samples of z~4.3 and z>5.8 quasars, recently published by the Sloan Digital Sky Survey (SDSS). Our main findings...
Gravitational lenses magnify up to one third of the most distant quasars (2002)
Exceptionally bright quasars with redshifts up to z=6.28 have recently been discovered. Quasars are thought to be powered by the accretion of gas onto supermassive black holes at the centres of...
Agol, Eric, Fluke, Christopher Jon, Wyithe, Stuart
Abstract not available.
Agol, Eric, Fluke, Christopher J., Wyithe, Stuart
Abstract not available.
Agol, Eric, Fluke, Christopher J., Wyithe, Stuart
Abstract not available.
Agol, Eric, Fluke, Christopher J., Wyithe, Stuart
Abstract not available.
Agol, Eric, Fluke, Christopher J., Wyithe, Stuart
Abstract not available.
Mid-infrared imaging of the Einstein Cross QSO (2001)
Agol, Eric, Fluke, Christopher J., Jones, Barbara, Wyithe, Stuart
Observations of the Einstein Cross QSO reveal that the mid-infrared region is unaffected by microlensing. Thus, the infrared emission region must be extended on a scale >1017 cm, ruling out...
Mid-infrared imaging of the Einstein Cross QSO (2001)
Agol, Eric, Fluke, Christopher J., Jones, Barbara, Wyithe, Stuart
Observations of the Einstein Cross QSO reveal that the mid-infrared region is unaffected by microlensing. Thus, the infrared emission region must be extended on a scale >1017 cm, ruling out...
Mid-infrared imaging of the Einstein Cross QSO (2001)
Agol, Eric, Fluke, Christopher J., Jones, Barbara, Wyithe, Stuart
Observations of the Einstein Cross QSO reveal that the mid-infrared region is unaffected by microlensing. Thus, the infrared emission region must be extended on a scale >1017 cm, ruling out...
Mid-infrared imaging of the Einstein Cross QSO (2001)
Agol, Eric, Fluke, Christopher J., Jones, Barbara, Wyithe, Stuart
Observations of the Einstein Cross QSO reveal that the mid-infrared region is unaffected by microlensing. Thus, the infrared emission region must be extended on a scale >1017 cm, ruling out...
Mid-infrared imaging of the Einstein Cross QSO (2001)
Agol, Eric, Fluke, Christopher J., Jones, Barbara, Wyithe, Stuart
Observations of the Einstein Cross QSO reveal that the mid-infrared region is unaffected by microlensing. Thus, the infrared emission region must be extended on a scale >1017 cm, ruling out...