Gas in simulations of high-redshift galaxies and minihaloes (2009)
Naoz, Smadar, Barkana, Rennan, Mesinger , Andrei
We study the gas content of haloes in the early universe using high-resolution hydrodynamical simulations. We extract from the simulations and also predict, based on linear theory, the halo mass for...
Lemze, Doron, Broadhurst, Tom, Rephaeli, Yoel, Barkana, Rennan, Umetsu, Keiichi
We examine the dynamics structure of the rich cluster A1689, combining VLT/VIMOS spectroscopy with Subaru/Suprime-Cam imaging. The radial velocity distribution of ~500 cluster members is bounded by a...
Studying the sources of cosmic reionization with 21-cm fluctuations (2009)
We explore the ability of measurements of the 21-cm power spectrum during reionization to enable the simultaneous reconstruction of the reionization history and the properties of the ionizing...
Measuring the History of Cosmic Reionization using the 21-cm PDF from Simulations (2009)
Ichikawa, Kazuhide, Barkana, Rennan, Iliev, Ilian T., Mellema, Garrelt, Shapiro, Paul
The 21-cm PDF (i.e., distribution of pixel brightness temperatures) is expected to be highly non-Gaussian during reionization and to provide important information on the distribution of density and...
Barkana, Rennan, Loeb, Abraham
Gravitational lensing observations of massive X-ray clusters imply a steep characteristic density profile marked by a central concentration of dark matter. The observed mass fraction within a...
Gas in Simulations of High Redshift Galaxies and Minihalos (2009)
Naoz, Smadar, Barkana, Rennan, Mesinger, Andrei
We study the gas content of halos in the early universe using high resolution hydrodynamical simulations. We extract from the simulations and also predict based on linear theory the halo mass for...
Lemze, Doron, Broadhurst, Tom, Rephaeli, Yoel, Barkana, Rennan, Umetsu, Keiichi
We examine the internal dynamics and caustic structure of the rich cluster A1689, combining VLT/VIMOS spectroscopy with Subaru/Suprime-Cam imaging. The radial velocity distribution of $\sim 500$...
The Infancy of Cosmic Reionization (2008)
We consider the early stages of cosmic hydrogen or helium reionization, when ionizing sources were still rare. We show that Poisson fluctuations in the galaxy distribution substantially affected the...
Studying the Sources of Cosmic Reionization with 21-cm Fluctuations (2008)
We explore the ability of measurements of the 21-cm power spectrum during reionization to enable the simultaneous reconstruction of the reionization history and the properties of the ionizing...
Large Einstein Radii: A Problem for LambdaCDM (2008)
Broadhurst, Tom, Barkana, Rennan
The Einstein radius of a cluster provides a relatively model-independent measure of the mass density of a cluster within a projected radius of ~ 150 kpc, large enough to be relatively unaffected by...
The infancy of cosmic reionization (2008)
We consider the early stages of cosmic hydrogen or helium reionization, when ionizing sources were still rare. We show that Poisson fluctuations in the galaxy distribution substantially affected the...
Mass and Gas Profiles in A1689: Joint X-ray and Lensing Analysis (2007)
Lemze, Doron, Barkana, Rennan, Broadhurst, Tom J., Rephaeli, Yoel
We carry out a comprehensive joint analysis of high quality HST/ACS and Chandra measurements of A1689, from which we derive mass, temperature, X-ray emission and abundance profiles. The X-ray...
Detecting Early Galaxies Through Their 21-cm Signature (2007)
New observations over the next few years of the emission of distant objects will help unfold the chapter in cosmic history around the era of the first galaxies. These observations will use the...
Barkana, Rennan, Loeb, Abraham
A new generation of radio telescopes are currently being built with the goal of tracing the cosmic distribution of atomic hydrogen at redshifts 6-15 through its 21-cm line. The observations will...
On Correlated Random Walks and 21-cm Fluctuations During Cosmic Reionization (2007)
Analytical approaches to galaxy formation and reionization are based on the mathematical problem of random walks with barriers. The statistics of a single random walk can be used to calculate...
The formation and gas content of high redshift galaxies and minihalos (2006)
We investigate the suppression of the baryon density fluctuations compared to the dark matter in the linear regime. Previous calculations predict that the suppression occurs up to a characteristic...
The Physics and Early History of the Intergalactic Medium (2006)
Barkana, Rennan, Loeb, Abraham
The intergalactic medium - the cosmic gas that fills the great spaces between the galaxies - is affected by processes ranging from quantum fluctuations in the very early universe to radiative...
The First Stars in the Universe and Cosmic Reionization (2006)
The earliest generation of stars, far from being a mere novelty, transformed the universe from darkness to light. The first atoms to form after the Big Bang filled the universe with atomic hydrogen...
The First Stars in The Universe (2006)
Naoz, Smadar, Noter, Shay, Barkana, Rennan
Large telescopes have allowed astronomers to observe galaxies that formed as early as 850 million years after the Big Bang. We predict when the first star that astronomers can observe formed in the...
Light-cone anisotropy in 21cm fluctuations during the epoch of reionization (2005)
Barkana, Rennan, Loeb, Abraham
The delay in light travel time along the line of sight generates an anisotropy in the power spectrum of 21cm brightness fluctuations from the epoch of reionization. We show that when the fluctuations...
Detecting Reionization in the Star Formation Histories of High-Redshift Galaxies (2005)
Barkana, Rennan, Loeb, Abraham
The reionization of cosmic hydrogen, left over from the big bang, increased its temperature to >~ 1.e4 K. This photo-heating resulted in an increase of the minimum mass of galaxies and hence a...
A Cosmic Relation between Extinction and Star Formation (2005)
Zoran, Oren, Barkana, Rennan, Thompson, Rodger I.
We study the relation between the star formation intensity of galaxies and the extinction by dust of their emitted light. We employ a detailed statistical analysis of Hubble Deep Field North data to...
Separating out the Alcock-Paczynski Effect on 21cm Fluctuations (2005)
We reconsider the Alcock-Paczynski effect on 21cm fluctuations from high redshift, focusing on the 21cm power spectrum. We show that at each accessible redshift both the angular diameter distance and...
Growth of Linear Perturbations before the Era of the First Galaxies (2005)
We calculate the evolution of linear density and temperature perturbations in a universe with dark matter, baryons, and radiation, from cosmic recombination until the epoch of the first galaxies. In...
Probing the Epoch of Early Baryonic Infall Through 21cm Fluctuations (2005)
Barkana, Rennan, Loeb, Abraham
After cosmological recombination, the primordial hydrogen gas decoupled from the cosmic microwave background (CMB) and fell into the gravitational potential wells of the dark matter. The neutral...
Detecting the Earliest Galaxies Through Two New Sources of 21cm Fluctuations (2004)
Barkana, Rennan, Loeb, Abraham
The first galaxies that formed at a redshift ~20-30 emitted continuum photons with energies between the Lyman-alpha and Lyman limit wavelengths of hydrogen, to which the neutral universe was...
A Method for Separating the Physics from the Astrophysics of High-Redshift 21cm Fluctuations (2004)
Barkana, Rennan, Loeb, Abraham
Fluctuations in the 21cm brightness from cosmic hydrogen at redshifts z > 6 were sourced by the primordial density perturbations from inflation as well as by the radiation from galaxies. We propose a...
Was the Universe Reionized at Redshift 10? (2004)
Loeb, Abraham, Barkana, Rennan, Hernquist, Lars
Recently, Pello et al. (2004) claimed to have discovered a galaxy at a redshift z=10, and identified a feature in its spectrum with a hydrogen Lyman-alpha emission line. If this identification is...
Unusually Large Fluctuations in the Statistics of Galaxy Formation at High Redshift (2003)
Barkana, Rennan, Loeb, Abraham
We show that various milestones of high-redshift galaxy formation, such as the formation of the first stars or the complete reionization of the intergalactic medium, occurred at different times in...
Barkana, Rennan, Loeb, Abraham
Lyman-alpha absorption is a prominent cosmological tool for probing both galactic halos and the intergalactic medium at high redshift. We consider a variety of sources that can be used as the...
GRBs vs. quasars: probing reionization vs. halo masses Elektronische Daten (2003)
Barkana, Rennan, Loeb, Avi, Astrophysics Conference
Talk Abstract von Kongress: Star and Structure Formation: From First Light to the Milky Way, Astrophysics Conference, August 18-22, 2003, ETH Zurich, Switzerland
A Model For Infall Around Virialized Halos (2002)
Motivated by the recent direct detection of cosmological gas infall, we develop an analytical model for calculating the mean density profile around an initial overdensity that later forms a dark...
Spectral Signature of Cosmological Infall of Gas Around the First Quasars (2002)
Barkana, Rennan, Loeb, Abraham
Recent observations have shown that, only a billion years after the Big Bang, the Universe was already lit up by bright quasars fuelled by the infall of gas onto supermassive black holes. The masses...
An Analytical Approach to Inhomogeneous Structure Formation (2002)
Scannapieco, Evan, Barkana, Rennan
We develop an analytical formalism that is suitable for studying inhomogeneous structure formation, by studying the joint statistics of dark matter halos forming at two points. Extending the Bond et...
Effective Screening due to Minihalos During the Epoch of Reionization (2002)
Barkana, Rennan, Loeb, Abraham
We show that the gaseous halos of collapsed objects introduce a substantial cumulative opacity to ionizing radiation, even after the smoothly distributed hydrogen in the intergalactic medium has been...
Recently, Lanzetta et al. (2002) have measured the distribution of star formation rate intensity in galaxies at various redshifts. This data set has a number of advantages relative to galaxy...
Did the Universe Reionize at Redshift Six? (2001)
In light of recent observations of spectra of the quasars SDSS 1030+0524 (Becker et al. 2001) and SDSS 1044-0125 (Djorgovski et al. 2001), we study the observational signatures of different stages of...
Warm Dark Matter, Small Scale Crisis, and the High Redshift Universe (2001)
Haiman, Zoltan, Barkana, Rennan, Ostriker, Jeremiah P.
Warm Dark Matter (WDM) models have recently been resurrected to resolve apparent conflicts of Cold Dark Matter (DM) models with observations. Endowing the DM particles with non-negligible velocities...
Constraints on Warm Dark Matter from Cosmological Reionization (2001)
Barkana, Rennan, Haiman, Zoltan, Ostriker, Jeremiah P.
We study the constraints that high-redshift structure formation in the universe places on warm dark matter (WDM) dominated cosmological models. We modify the extended Press-Schechter formalism to...
In the Beginning: The First Sources of Light and the Reionization of the Universe (2000)
Barkana, Rennan, Loeb, Abraham
The formation of the first stars and quasars marks the transformation of the universe from its smooth initial state to its clumpy current state. In popular cosmological models, the first sources of...
The Reionization of the Universe by the First Stars and Quasars (2000)
Loeb, Abraham, Barkana, Rennan
The first light from stars and quasars ended the ``dark ages'' of the universe and led to the reionization of hydrogen by redshift 7. Current observations are at the threshold of probing this epoch....
New VLBI Constraints for 0957+561 Lens Models (2000)
Haarsma, Deborah, Leh'ar, Joseph, Barkana, Rennan
Time-delay measurements of 0957+561 based on radio monitoring now agree with optical monitoring. Recent models incorporate many recent observations, but the systematic uncertainties in the models...
Cold and Fuzzy Dark Matter (2000)
Hu, Wayne, Barkana, Rennan, Gruzinov, Andrei
Cold dark matter (CDM) models predict small-scale structure in excess of observations of the cores and abundance of dwarf galaxies. These problems might be solved, and the virtues of CDM models...
Gravitational Lensing of High Redshift Sources (2000)
Barkana, Rennan, Hogg, David, Loeb, Abraham, Blandford, Roger
The combination of deep exposures and high resolution offered by telescopes in space allows the detection of lensing over a wide range of source redshifts and lens masses. As an example, we model a...
Identifying the Reionization Redshift from the Cosmic Star Formation Rate (2000)
Barkana, Rennan, Loeb, Abraham
We show that the cosmic star formation rate per comoving volume should exhibit a distinct drop around the reionization redshift, when the HII regions in the intergalactic medium around individual...
Barkana, Rennan, Loeb, Abraham
Direct observations of the first generation of luminous objects will likely become feasible over the next decade. The advent of the Next Generation Space Telescope (NGST) will allow imaging of...
The Photo-Evaporation of Dwarf Galaxies During Reionization (1999)
Barkana, Rennan, Loeb, Abraham
During the period of reionization the Universe was filled with a cosmological background of ionizing radiation. By that time a significant fraction of the cosmic gas had already been incorporated...
A possible gravitational lens in the Hubble Deep Field South (1998)
Barkana, Rennan, Blandford, Roger, Hogg, David
We model an apparent gravitational lens system HDFS 2232509-603243 in the Hubble Deep Field South. The system consists of a blue V=25 mag arc separated by 0.9 arcsec from a red V=22 mag elliptical...
A reassessment of the data and models of the gravitational lens Q0957+561 (1998)
Barkana, Rennan, Lehar, Joseph, Falco, Emilio E., Grogin, Norman A., Keeton, Charles R., Shapiro, Irwin I.
We examine models of the mass distribution for the first known case of gravitational lensing. Several new sets of constraints are used, based on recent observations. We remodel the VLBI observations...
Fast calculation of a family of elliptical mass gravitational lens models (1998)
Because of their simplicity, axisymmetric mass distributions are often used to model gravitational lenses. Since galaxies are usually observed to have elliptical light distributions, mass...
Analysis of Time Delays in the Gravitational Lens PG1115+080 (1997)
We present a new method for determining time delays among the light curves of various images in a gravitational lens. The method is based on constructing a simple model for the source variation and...