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The decline in abundance of Lyman-$\alpha$ (Ly$\alpha$) emitting galaxies at $z \gtrsim 6$ is a powerful and commonly used probe to constrain the progress of cosmic reionization. We use the CoDaII simulation, which is a radiation…

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…

Cosmology and Nongalactic Astrophysics · Physics 2018-03-28 Frederick B. Davies , Joseph F. Hennawi , Anna-Christina Eilers , Zarija Lukić

The observed number density of Lyman-alpha sources implies a minimum volume of the inter-galactic medium that must be ionized, in order to allow the Lyman-alpha photons to escape attenuation. We estimate this volume by assigning to each…

Astrophysics · Physics 2009-11-11 Sangeeta Malhotra , James Rhoads

A variety of independent observational studies have now reported a significant decline in the fraction of Lyman-break galaxies which exhibit Ly-a emission over the redshift interval z=6-7. In combination with the strong damping wing…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 James S. Bolton , Martin G. Haehnelt

Several Lyman-alpha (Ly$\alpha$) emitters deep into the reionization era exhibit double-peaked Ly$\alpha$ emission profiles, raising the question of how the intergalactic medium can transmit photons blueward of the Ly$\alpha$ resonance at…

We combine a high-resolution hydro-simulation of the LambdaCDM cosmology with two radiative transfer schemes (for continuum and line radiation) to predict the properties, spectra and spatial distribution of fluorescent Ly-alpha emission at…

Astrophysics · Physics 2009-11-10 Sebastiano Cantalupo , Cristiano Porciani , Simon J. Lilly , Francesco Miniati

An appealing approach for studying the reionization history of the Universe is to measure the redshift evolution of the Lyman-alpha fraction, the percentage of Lyman-break selected galaxies that emit appreciably in the Ly-alpha line. This…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 Jessie Taylor , Adam Lidz

Observed scatter in the Lyman-alpha opacity of quasar sightlines at $z<6$ has motivated measurements of the correlation between Ly$\alpha$ opacity and galaxy density, as models that predict this scatter make strong and sometimes opposite…

The inhomogeneous cosmological reionization process leaves tangible imprints in the intergalactic medium down to z=4-5. The Lyman-alpha forest flux power spectrum provides a potentially powerful probe of the epoch of reionization. With the…

Cosmology and Nongalactic Astrophysics · Physics 2009-11-13 Renyue Cen , Patrick McDonald , Hy Trac , Abraham Loeb

The average rate of emission of ionizing radiation per unit volume (or emissivity) in the universe can be calculated as the ratio of the intensity of the ionizing background to the mean free path of ionizing photons. The intensity of the…

Astrophysics · Physics 2009-11-07 Jordi Miralda-Escude

Lyman-$\alpha$ (Ly$\alpha$) emitting galaxies are powerful tools to probe the late stages of cosmic reionization. The observed sudden drop in Ly$\alpha$ fraction at $z>6$ is often interpreted as a sign of reionization, since the…

Cosmology and Nongalactic Astrophysics · Physics 2021-03-03 Sultan Hassan , Max Gronke

Recent observations of high-redshift galaxies and quasars indicate that the hydrogen component of the intergalactic medium (IGM) must have been reionized at some redshift z>6. Prior to complete reionization, sources of ultraviolet radiation…

Astrophysics · Physics 2009-10-31 Piero Madau , Martin J. Rees

The Epoch of Reionization (EoR) represents a milestone in the evolution of our Universe. Star-forming galaxies that existed during the EoR likely emitted a significant fraction (~5-40%) of their bolometric luminosity as Lyman Alpha (Lya)…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-22 Mark Dijkstra

The early stage in the formation of a galaxy inevitably involves a spatially extended distribution of infalling, cold gas. If a central luminous quasar turned on during this phase, it would result in significant extended Lyman alpha…

Astrophysics · Physics 2009-11-06 Zoltan Haiman , Martin J. Rees

We investigate Lyman-$\alpha$ transmission spikes at $z > 5$ in synthetic quasar spectra, and discuss their connection to the properties of the intergalactic medium and their ability to constrain reionization models. We use state-of-the-art…

Cosmology and Nongalactic Astrophysics · Physics 2019-05-08 Enrico Garaldi , Nickolay Gnedin , Piero Madau

The hydrogen Lyman-$\alpha$ (H {\sc i} Ly$\alpha$) emission during solar flares has rarely been studied in spatially resolved images and its physical origin has not been fully understood. In this paper, we present novel Ly$\alpha$ images…

Solar and Stellar Astrophysics · Physics 2022-09-21 Ying Li , Qiao Li , De-Chao Song , Andrea Francesco Battaglia , Hualin Xiao , Säm Krucker , Udo Schühle , Hui Li , Weiqun Gan , M. D. Ding

Lyman-$\alpha$ damping wings towards quasars are a highly sensitive probe of the neutral hydrogen (HI) content in the foreground intergalactic medium (IGM), not only constraining the global timing of reionization but also the \textit{local}…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-01 Timo Kist , Joseph F. Hennawi , Frederick B. Davies

We present a new flexible Bayesian framework for directly inferring the fraction of neutral hydrogen in the intergalactic medium (IGM) during the Epoch of Reionization (EoR, z~6-10) from detections and non-detections of Lyman Alpha…

Cosmology and Nongalactic Astrophysics · Physics 2018-03-28 Charlotte A. Mason , Tommaso Treu , Mark Dijkstra , Andrei Mesinger , Michele Trenti , Laura Pentericci , Stephane de Barros , Eros Vanzella

The presence of excess scatter in the Ly-$\alpha$ forest at $z\sim 5.5$, together with the existence of sporadic extended opaque Gunn-Peterson troughs, has started to provide robust evidence for a late end of hydrogen reionisation. However,…

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…