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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

Understanding the escape of ionizing (Lyman continuum) photons from galaxies is vital for determining how galaxies contributed to reionization in the early universe. While directly detecting Lyman continuum from high redshift galaxies is…

An analysis of the dynamics of a star formation event is performed. It is shown that galaxies able to drive leftover gas to sufficient altitudes in a few million years are characterized by two basic properties: small sizes (<1kpc) and high…

Astrophysics of Galaxies · Physics 2020-02-05 Renyue Cen

We use Hubble space telescope data of 45 nearby star-forming galaxies to investigate properties of Lyman-alpha (Ly$\alpha$) halos, Ly$\alpha$ morphology, and the star-forming characteristics of galaxies. We study how the morphology of…

We have recently discovered five Lyman continuum leaking galaxies at z~0.3, selected for their compactness, intense star-formation, and high [OIII]/[OII] ratio (Izotov et al. 2016ab). Here we derive their ionizing photon production…

Astrophysics of Galaxies · Physics 2016-06-29 D. Schaerer , Y. I. Izotov , A. Verhamme , I. Orlitova , T. X. Thuan , G. Worseck , N. Guseva

Star forming galaxies are believed to be a major source of Lyman Continuum (LyC) radiation responsible for reionizing the early Universe. Direct observations of escaping ionizing radiation have however been few and with low escape…

Astrophysics of Galaxies · Physics 2017-03-08 T. Emil Rivera-Thorsen , Göran Östlin , Matthew Hayes , Johannes Puschnig

The Lyman-$\alpha$ (Lya) line of hydrogen is a well-known tracer of galaxies at high-z. However, the connection between Lya observables and galaxy properties has not fully been established, limiting the use of the line to probe the physics…

Finding reliable indicators of Lyman continuum (LyC) photon leakage from galaxies is essential in order to infer their escape fraction in the epoch of reionisation, where direct measurements of LyC flux are impossible. To this end, here we…

Astrophysics of Galaxies · Physics 2022-10-24 A. Saxena , E. Cryer , R. S. Ellis , L. Pentericci , A. Calabrò , S. Mascia , A. Saldana-Lopez , D. Schaerer , H. Katz , M. Llerena , R. Amorín

Sources that leak Lyman-continuum (LyC) photons and lead to the reionisation of the universe are intensely studied using multiple observing facilities. Recently, the Low-redshift LyC Survey (LzLCS) has found the first large sample of LyC…

Ly$\alpha$ absorption spectra of QSOs at redshifts $z\simeq6$ show complete Gunn-Peterson absorption troughs (dark gaps) separated by tiny leaks. The dark gaps are from the intergalactic medium (IGM) where the density of neutral hydrogen…

Astrophysics · Physics 2009-11-13 Long-Long Feng , Hong-Guang Bi , Ji-Ren Liu , Li-Zhi Fang

Reliable indirect diagnostics of LyC photon escape from galaxies are required to understand which sources were the dominant contributors to reionization. While multiple LyC escape fraction ($f_{\rm esc}$) indicators have been proposed to…

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…

Various types of galaxies observed in the cosmological scales show P-Cygni type profiles in the Lyman alpha emission lines. A Monte Carlo code is developed to investigate the Lyman alpha line transfer in an optically thick and moving medium…

Astrophysics · Physics 2016-08-30 Sang-Hyeon Ahn , Hee-Won Lee

Understanding the ionizing photon escape from galaxies is essential for studying Cosmic Reionization. With a sample of 23 Lyman Continuum (LyC) leakers at $3<z<4.5$ in the GOODS-S field, we investigate their morphologies using…

Astrophysics of Galaxies · Physics 2024-12-12 Shuairu Zhu , Zhen-ya Zheng , Fang-Ting Yuan , Chunyan Jiang , Ruqiu Lin

We present detailed predictions for the properties of Ly-alpha-emitting galaxies in the framework of the Lambda-CDM cosmology, calculated using the semi-analytical galaxy formation model GALFORM. We explore a model which assumes a top-heavy…

Astrophysics · Physics 2009-11-13 M. Le Delliou , C. G. Lacey , C. M. Baugh , S. L. Morris

We compute the polarization of the Lyman alpha line photons emerging from an anisotropically expanding and optically thick medium, which is expected to operate in many Lyman alpha emitting objects including the primeval galaxy DLA~2233+131…

Astrophysics · Physics 2009-10-30 Hee-Won Lee , Sang-Hyeon Ahn

Ly$\alpha$ emission is widely used to detect and confirm high-redshift galaxies and characterize the evolution of the intergalactic medium. However, many galaxies do not display Ly$\alpha$ emission in typical spectroscopic observations, and…

Astrophysics of Galaxies · Physics 2020-01-08 Ryan F. Trainor , Allison L. Strom , Charles C. Steidel , Gwen C. Rudie , Yuguang Chen , Rachel L. Theios

We conducted systematic radiative transfer (RT) modeling of the Mg II doublet line profiles for 33 low-redshift Lyman continuum (LyC) leakers, and Ly$\alpha$ modeling for a subset of six objects, using a multiphase, clumpy circumgalactic…

We present Monte Carlo calculations of Lyman alpha (Lya) radiative transfer through collapsing gas clouds, representing proto-galaxies that are caught in the process of their assembly. Such galaxies produce Lya flux over an extended solid…

Astrophysics · Physics 2008-11-26 Mark Dijkstra , Zoltan Haiman , Marco Spaans

The geometry of the neutral gas in and around galaxies is a key regulator of the escape of ionizing photons. We present the first statistical study aiming at linking the neutral and ionized gas distributions to the Lyman continuum (LyC)…

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