Understanding Lyα emitters

Abstract

This publication contains the conference summary of the Understanding Lyα Emitters conference held at the Max Planck Institute for Astronomy in Heidelberg October 6 -10, 2008. The scope of the conference was to bring together most of the scientists working in the field of Lyα emitters, whether at low or high redshift, or on observational or theoretical aspects, and to summarise how far the field of study of galaxies with Lyα emission has come. An outlook towards the future of the field was also desired. As part of the conference, two days were dedicated to in total six discussion sessions. The topics were i) new methods and selection methods, ii) morphology, iii) what can the local Universe observations tell us about the high redshift Universe?, iv) clustering, v) SED fitting and vi) Lyα blobs. The chairs of those sessions were asked to summarise the discussions, as presented in these proceedings. AbstractAs the topics of study of Lyα emitters evolve, new selection methods are being developed to find these high redshift galaxies. In this proceedings, three new methods are presented, based on large integral field unit spectrographs, ultra-deep slit spectroscopy and serendipitous discoveries. AbstractLyman Alpha Emitters (LAEs) are high-redshift galaxies that are believed to be actively star-forming and low in mass. Although such a population of galaxies would not be expected to lie on the Hubble Sequence, there is much we can learn from their morphological properties, including the size and distribution of their star-forming regions, the spatial correlation between emission in different bandpasses, and the possible presence of a merger/interaction with one or more neighboring galaxies. Early morphological studies suggest that most LAEs are small in size ( 1 kpc) and concentrated, but some (∼ 20-45%) are seen to display clumpy/irregular morphologies extending over larger radii. Constructing a more detailed picture will require a standard set of depth-independent morphological diagnostics for high-redshift galaxies. These diagnostics can then be measured differentially with redshift, shedding light on the evolution of the galaxy formation process with time.

Eclipsing damped Ly α systems in the Sloan Digital Sky Survey Data Release 12★

“…14, the luminosity et al (2008). LAEs are low-mass high-redshift galaxies that are believed to be actively forming stars (Nilsson & Meisenheimer, 2009). The Lyα emission from LAEs is primarily due to star formation although some AGN activity has also been reported in some LAEs, especially in those with high luminosities (Log L(Lyα) > 43.5 erg s −1 , see Ouchi et al (2008); Overzier et al (2013)).…”

Recent Advances in Cosmological Hydrogen Reionization

“…If the IGM is fully ionized, then any photons that escape their galaxy's ISM will no longer scatter. This is the case at z < 6, where many galaxies show strong Lyα emission lines [54]. If a galaxy emits Lyα photons into an IGM that is not fully ionized, however, then its Lyα photons will be scattered into a low surface-brightness halo.…”

HETDEX Public Source Catalog 1—Stacking 50,000 Lyman Alpha Emitters ∗

“…Only a relative few of these LAEs have sufficiently bright continua to be selected as Lyman break galaxies (LBGs; Guhathakurta et al 1990;Madau et al 1996;Steidel et al 1996;Shapley et al 2003). Generally, the LAEs in the HETDEX redshift window are compact, low-metallicity, rapidly star-forming galaxies (Gawiser et al 2007;Nilsson & Meisenheimer 2009;Finkelstein 2010, and many others).…”