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Lyman-Alpha (Lya) photons emitted in star-forming galaxies undergo complex radiative transfer through the interstellar (ISM), circumgalactic (CGM), and intergalactic medium (IGM), imprinting characteristic signatures on their observed line…

We investigate Lyman-alpha (Ly$\alpha$) transmission spikes at $5.2 < z < 6.8$ using synthetic quasar spectra from the ``Cosmic Reionization On Computers" simulations. We focus on understanding the relationship between these spikes and the…

Cosmology and Nongalactic Astrophysics · Physics 2025-07-01 Hanjue Zhu , Nickolay Gnedin , Camille Avestruz

We demonstrate the redshift-evolution of the spectral profile of H i Lyman-alpha (Ly{\alpha}) emission from star-forming galaxies. In this first study we pay special attention to the contribution of blueshifted emission. At redshift z =…

Astrophysics of Galaxies · Physics 2021-02-18 Matthew J. Hayes , Axel Runnholm , Max Gronke , Claudia Scarlata

JWST spectra revealing Lyman-$\alpha$ (Ly$\alpha$) absorption in $z\sim 5-14$ galaxies offer a unique probe of reionization's earliest stages. However, disentangling absorption by the increasingly neutral intergalactic medium (IGM) from…

The escape fraction of LyC ionizing radiation ($f_{lyc}$) is crucial for understanding reionization, yet difficult to measure at $z \gtrsim 4$. Recently, studies have focused on calibrating indirect indicators of $f_{lyc}$ at $z \sim 0.3$,…

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…

Ly$\alpha$ emission is possibly the best indirect diagnostic of Lyman continuum (LyC) escape since the conditions that favor the escape of Ly$\alpha$ photons are often the same that allows for the escape of LyC photons. In this work, we…

We present a semi-analytical model of star formation which explains simultaneously the observed UV luminosity function of high redshift Lyman break galaxies (LBGs) and luminosity functions of Lyman-alpha emitters. We consider both models…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Saumyadip Samui , Raghunathan Srianand , Kandaswamy Subramanian

We use a semi-analytic model of Lyman alpha emitters (LAEs) to constrain the reionization history. By considering two physically motivated scenarios in which reionization ends either early (ERM, z_i ~ 7) or late (LRM, z_i ~ 6), we fix the…

Astrophysics · Physics 2009-11-13 Pratika Dayal , Andrea Ferrara , Simona Gallerani

Star-forming galaxies are the sources likely to have reionized the universe. As we cannot observe them directly due to the opacity of the intergalactic medium at $z\gtrsim5$, we study $z\sim3\text{--}5$ galaxies as proxies to place…

Recent work has shown that UV-luminous reionization-era galaxies often exhibit strong Lyman-alpha emission despite being situated at redshifts where the IGM is thought to be substantially neutral. It has been argued that this enhanced…

Ly$\alpha$ emission from galaxies can be utilized to characterize the ionization state in the intergalactic medium (IGM). We report our search for Ly$\alpha$ emission at $z>7$ using a comprehensive Keck/MOSFIRE near-infrared spectroscopic…

Assessing the contribution of ionizing sources to cosmic reionization is a central goal of extragalactic astrophysics. Understanding and quantifying ionizing escape remains challenging near the epoch of reionization. We present the…

The highly neutral inter-galactic medium (IGM) during the Epoch of Reionization (EoR) is expected to suppress Ly$\alpha$ emission with damping-wing absorption, causing nearly no Ly$\alpha$ detection from star-forming galaxies at $z{\sim}8$.…

Cosmology and Nongalactic Astrophysics · Physics 2022-01-05 Yuxiang Qin , J. Stuart B. Wyithe , Pascal A. Oesch , Garth D. Illingworth , Ecaterina Leonova , Simon J. Mutch , Rohan P. Naidu

We present observations of a luminous galaxy at redshift z=6.573 --- the end of the reioinization epoch --- which has been spectroscopically confirmed twice. The first spectroscopic confirmation comes from slitless HST ACS grism spectra…

A large number of high-redshift galaxies have been discovered via their narrow-band Lya line or broad-band continuum colors in recent years. The nature of the escaping process of photons from these early galaxies is crucial to understanding…

Cosmology and Nongalactic Astrophysics · Physics 2014-04-16 Hidenobu Yajima , Yuexing Li , Qirong Zhu , Tom Abel , Caryl Gronwall , Robin Ciardullo

Galaxies represent one of the preferred candidate sources to drive the reionization of the universe. Even as gains are made in mapping the galaxy UV luminosity density to z>6, significant uncertainties remain regarding the conversion to the…

Astrophysics of Galaxies · Physics 2016-11-15 R. J. Bouwens , R. Smit , I. Labbe , M. Franx , J. Caruana , P. Oesch , M. Stefanon , N. Rasappu

Constraining the escape fraction of Lyman Continuum (LyC) photons from high-redshift galaxies is crucial to understanding reionization. Recent observations have demonstrated that various characteristics of the Ly$\alpha$ emission line…

The observed scatter in intergalactic Lyman-$\alpha$ opacity at $z \lesssim 6$ requires large-scale fluctuations in the neutral fraction of the intergalactic medium (IGM) after the expected end of reionization. Post-reionization models that…

Cosmology and Nongalactic Astrophysics · Physics 2018-08-22 George D. Becker , Frederick B. Davies , Steven R. Furlanetto , Matthew A. Malkan , Elisa Boera , Craig Douglass

We report the spectroscopic confirmation of two Lyman break galaxies at redshift > 7. The galaxies were observed as part of an ultra-deep spectroscopic campaign with FORS2 at the ESO/VLT for the confirmation of z~7 ``z--band dropout''…