Steven Furlanetto

First Light Sources at the End of the Dark Ages: Direct Observations of Population III Stars, Proto-Galaxies, and Supernovae During the Reionization Epoch (2009)

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...

Cooke, Jeff, Cooray, Asantha, Chary, Ranga-Ram, Bromm, Volker, Cen, Renyue, Ellis, Richard, ...

The cosmic dark ages are the mysterious epoch during which the pristine gas began to condense and ultimately form the first stars. Although these beginnings have long been a topic of theoretical...

Cosmology from the Highly-Redshifted 21 cm Line (2009)

Furlanetto, Steven, Lidz, Adam, Loeb, Abraham, McQuinn, Matthew, Pritchard, Jonathan, Shapiro, Paul, ...

One of the next decade's most exciting prospects is to explore the cosmic "dark ages," during which the first stars in the Universe formed, with the 21 cm line of neutral hydrogen. At z>6, this light...

Astrophysics from the Highly-Redshifted 21 cm Line (2009)

Furlanetto, Steven, Lidz, Adam, Loeb, Abraham, McQuinn, Matthew, Pritchard, Jonathan, Aguirre, James, ...

The cosmic dark ages and the epoch of reionization, during which the first generations of stars and galaxies formed, are among the most compelling frontiers of extragalactic astrophysics and...

A New Era in Extragalactic Background Light Measurements: The Cosmic History of Accretion, Nucleosynthesis and Reionization (2009)

Cooray, Asantha, Amblard, Alexandre, Beichman, Charles, Benford, Dominic, Bernstein, Rebecca, Bock, James, ...

(Brief Summary) What is the total radiative content of the Universe since the epoch of recombination? The extragalactic background light (EBL) spectrum captures the redshifted energy released from...

Spatial Correlations in the Helium-Ionizing Background (2009)

The Equation of State of the Intergalactic Medium After Hydrogen Reionization (2009)

After quasars ionize intergalactic HeII at z~3, a large radiation field builds up above the HeII ionization edge. Unlike the background responsible for HI ionizations, this field should be highly...

Fluctuations in the Ionizing Background During and After Helium Reionization (2008)

We use an analytic model to study how inhomogeneous hydrogen reionization affects the temperature distribution of the intergalactic medium (IGM). During this process, the residual energy of each...

The ionizing background at the end of overlap (2008)

The radiation background above the ionization edge of HeII varies strongly during and after helium reionization, because the attenuation length of such photons is relatively short (

Furlanetto, Steven, Mesinger, Andrei

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...

Probing Reionization with the 21 cm-Galaxy Cross Power Spectrum (2008)

Lidz, Adam, Zahn, Oliver, Furlanetto, Steven, McQuinn, Matthew, Hernquist, Lars, Zaldarriaga, Matias

The cross-correlation between high redshift galaxies and 21 cm emission from the high redshift intergalactic medium (IGM) promises to be an excellent probe of the Epoch of Reionization (EoR). On...

Fossil Ionized Bubbles Around Dead Quasars During Reionization (2008)

Furlanetto, Steven, Haiman, Zoltan, Oh, S. Peng

One of the most dramatic signatures of the reionization era may be the enormous ionized bubbles around luminous quasars (with radii reaching ~40 comoving Mpc), which may survive as "fossil'' ionized...

The History and Morphology of Helium Reionization (2007)

Inhomogeneous Helium Reionization and the Equation of State of the Intergalactic Medium (2007)

A variety of observations now indicate that intergalactic helium was fully ionized by z~3. The most recent measurements of the high-redshift quasar luminosity function imply that these sources had...

Lyman-alpha Damping Wing Constraints on Inhomogeneous Reionization (2007)

The temperature of the intergalactic medium (IGM) is set by the competition between photoheating and adiabatic cooling, which are usually assumed to define a tight equation of state in which the...

Lyman-alpha Emitters During the Early Stages of Reionization (2007)

One well-known way to constrain the hydrogen neutral fraction, x_H, of the high-redshift intergalactic medium (IGM) is through the shape of the red damping wing of the Lya absorption line. We examine...

Reionization and the large-scale 21 cm-cosmic microwave background cross correlation (2007)

We investigate the potential of exploiting Lya Emitters (LAEs) to constrain the volume-weighted mean neutral hydrogen fraction of the IGM, x_H, at high redshifts (specifically z~9). We use...

Adshead, Peter, Furlanetto, Steven

Of the many probes of reionization, the 21 cm line and the cosmic microwave background (CMB) are among the most effective. We examine how the cross-correlation of the 21 cm brightness and the CMB...

Efficient Simulations of Early Structure Formation and Reionization (2007)

Spin Exchange Rates in Proton-Hydrogen Collisions (2007)

We present a method to construct semi-numerical ``simulations'', which can efficiently generate realizations of halo distributions and ionization maps at high redshifts. Our procedure combines an...

Furlanetto, Steven, Furlanetto, Michael

The spin temperature of neutral hydrogen, which determines the optical depth and brightness of the 21 cm line, is determined by the competition between radiative and collisional processes. Here we...

The Cross-Correlation of High-Redshift 21 cm and Galaxy Surveys (2006)

Furlanetto, Steven, Lidz, Adam

We study the detectability of the cross-correlation between 21 cm emission from the intergalactic medium and the galaxy distribution during (and before) reionization. We show that first-generation 21...

The Effects of Dark Matter Decay and Annihilation on the High-Redshift 21 cm Background (2006)

Furlanetto, Steven, Oh, S. Peng, Pierpaoli, Elena

The radiation background produced by the 21 cm spin-flip transition of neutral hydrogen at high redshifts can be a pristine probe of fundamental physics and cosmology. At z~30-300, the intergalactic...

Spin Exchange Rates in Electron-Hydrogen Collisions (2006)

Furlanetto, Steven, Furlanetto, Michael

The spin temperature of neutral hydrogen, which determines the 21 cm optical depth and brightness temperature, is set by the competition between radiative and collisional processes. In the...

Cosmology at Low Frequencies: The 21 cm Transition and the High-Redshift Universe (2006)

Furlanetto, Steven, Oh, S. Peng, Briggs, Frank

Observations of the high-redshift Universe with the 21 cm hyperfine line of neutral hydrogen promise to open an entirely new window onto the early phases of cosmic structure formation. Here we review...

The Scattering of Lyman-series Photons in the Intergalactic Medium (2006)

Furlanetto, Steven, Pritchard, Jonathan R.

We re-examine scattering of photons near the Lyman-alpha resonance in the intergalactic medium (IGM). We first derive a general integral solution for the radiation field around resonance when spin...

The 21 Centimeter Forest (2006)

Redshifted 21 Centimeter Emission from Minihalos Before Reionization (2006)

We examine the prospects for studying the pre-reionization intergalactic medium (IGM) through the so-called 21 cm forest in spectra of bright high-redshift radio sources. We first compute the...

The Global 21 Centimeter Background from High Redshifts (2006)

Before reionization, the intergalactic medium (IGM) may have been sufficiently cold for low-mass "minihalos" to condense out of the gas and subsequently affect reionization. Previous work has shown...

The Evidence of Absence: Galaxy Voids in the Excursion Set Formalism (2005)

We consider the evolution of the sky-averaged 21 cm background during the early phases of structure formation. Using simple analytic models, we calculate the thermal and ionization histories,...

Furlanetto, Steven, Piran, Tsvi

We present an analytic model for the sizes of voids in the galaxy distribution. Peebles and others have recently emphasized the possibility that the observed characteristics of voids may point to a...

Highly-Ionized Oxygen Absorbers in the Intergalactic Medium (2004)

Furlanetto, Steven, Phillips, Lara Arielle, Kamionkowski, Marc

Recent ultraviolet and X-ray observations of intergalactic OVI and OVII absorption systems along lines of sight to bright quasars have opened a new window onto the ``warm-hot intergalactic medium''...

The Temperature Structure of the Warm-Hot Intergalactic Medium (2004)

Yoshida, Naoki, Furlanetto, Steven, Hernquist, Lars

We study the temperature structure of the intergalactic medium (IGM) using a large cosmological N-body/SPH simulation. We employ a two-temperature model for the thermal evolution of the ionized gas,...

Lyman-alpha Emission from Structure Formation (2004)

Furlanetto, Steven, Schaye, Joop, Springel, Volker, Hernquist, Lars

The nature of the interaction between galaxies and the intergalactic medium (IGM) is one of the most fundamental problems in astrophysics. The accretion of gas onto galaxies provides fuel for star...

Is Double Reionization Physically Plausible? (2004)

21 cm Tomography of the High-Redshift Universe with the Square Kilometer Array (2004)

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...

Furlanetto, Steven, Briggs, Frank

We discuss the prospects for ``tomography'' of the intergalactic medium (IGM) at high redshifts using the 21 cm transition of neutral hydrogen. Existing observational constraints on the epoch of...

Polarization Signals of the 21 cm Background from the Era of Reionization (2004)

Cooray, Asantha, Furlanetto, Steven

While emission and absorption lines of the 21 cm spin-flip transition of neutral Hydrogen are intrinsically unpolarized, a magnetic field creates left- and right-handed polarized components through...

Constraining the Topology of Reionization Through Lyman-alpha Absorption (2004)

Furlanetto, Steven, Hernquist, Lars, Zaldarriaga, Matias

The reionization of hydrogen in the intergalactic medium (IGM) is a crucial landmark in the history of the universe, but the processes through which it occurs remain mysterious. In particular, recent...

Statistical Probes of Reionization With 21 cm Tomography (2004)

Furlanetto, Steven, Zaldarriaga, Matias, Hernquist, Lars

We consider the degree to which "21 cm tomography" of the high-redshift Universe can distinguish different ionization histories. Using a new analytic model for the size distribution of HII regions...

The Growth of HII Regions During Reionization (2004)

Furlanetto, Steven, Zaldarriaga, Matias, Hernquist, Lars

Recently, there has been a great deal of interest in understanding the reionization of hydrogen in the intergalactic medium (IGM). One of the major outstanding questions is how this event proceeds on...

Free-Free Emission at Low Radio Frequencies (2004)

Cooray, Asantha, Furlanetto, Steven

We discuss free-free radio emission from ionized gas in the intergalactic medium. Because the emissivity is proportional to the square of the electron density, the mean background is strongly...

Large-Scale Structure Shocks at Low and High Redshifts (2003)

21 Centimeter Fluctuations from Cosmic Gas at High Redshifts (2003)

Cosmological simulations show that, at the present time, a substantial fraction of the gas in the intergalactic medium (IGM) has been shock-heated to T>10^5 K. Here we develop an analytic model to...

Zaldarriaga, Matias, Furlanetto, Steven, Hernquist, Lars

The relatively large Thomson optical depth, tau_e, inferred recently from the WMAP observations suggests that the Universe was reionized in a more complex manner than previously believed. However,...

Mapping the Cosmic Web with Ly-alpha Emission (2003)

Furlanetto, Steven, Schaye, Joop, Springel, Volker, Hernquist, Lars

We use a high-resolution cosmological simulation to predict the distribution of HI Ly-alpha emission from the low-redshift (z10^2 kpc) ``coronae'' of optically thin gas with Ly-alpha surface...

Ultraviolet Line Emission from Metals in the Low-Redshift Intergalactic Medium (2003)

Furlanetto, Steven, Schaye, Joop, Springel, Volker, Hernquist, Lars

We use a high-resolution cosmological simulation that includes hydrodynamics, multiphase star formation, and galactic winds to predict the distribution of metal line emission at z~0 from the...

Observing the Reionization Epoch Through 21 Centimeter Radiation (2003)

Furlanetto, Steven, Sokasian, Aaron, Hernquist, Lars

We study the observability of the reionization epoch through the 21 cm hyperfine transition of neutral hydrogen. We use a high-resolution cosmological simulation (including hydrodynamics) together...

Metal Absorption Lines as Probes of the Intergalactic Medium Prior to the Reionization Epoch (2002)

The 21 cm Forest: Radio Absorption Spectra as Probes of Minihalos Before Reionization (2002)

Winds from star-forming galaxies provide the most promising explanation for the enrichment of the intergalactic medium with heavy elements. Theoretical and observational arguments indicate that the...

Identifying Gamma-Ray Burst Remnants Through Positron Annihilation Radiation (2002)

We study the absorption along lines of sight toward high-z radio sources caused by the 21 cm transition of neutral hydrogen in the intergalactic medium (IGM) before reionization. Using semi-analytic...

Emission of Positron Annihilation Line Radiation by Clusters of Galaxies (2002)

We model the annihilation of relic positrons produced in a gamma-ray burst (GRB) after its afterglow has faded. We find that the annihilation signal from at least one GRB remnant in the Milky Way...

An Intergalactic Magnetic Field from Quasar Outflows (2001)

Clusters of galaxies are enriched with positrons from jets of active galactic nuclei (AGNs) or from the interaction of cosmic rays with the intracluster gas. We follow the cooling of these positrons...

Constraining the Collisional Nature of the Dark Matter Through Observations of Gravitational Wakes (2001)

Outflows from quasars inevitably pollute the intergalactic medium (IGM) with magnetic fields. The short-lived activity of a quasar leaves behind an expanding magnetized bubble in the IGM. We model...

Intergalactic Magnetic Fields from Quasar Outflows (2001)

We propose to use gravitational wakes as a direct observational probe of the collisional nature of the dark matter. We calculate analytically the structure of a wake generated by the motion of a...