EDP Sciences Journals List
Advanced Search
Subscriber Authentication Point
Home All issues Volume 430/3 Article
Free access article

Issue A&A
Volume 430, Number 3, February II 2005
Page(s) 877 - 891
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20035863



A&A 430, 877-891 (2005)
DOI: 10.1051/0004-6361:20035863

The expected abundance of Lyman- $\alpha$ emitting primeval galaxies

I. General model predictions
E. Thommes1, 2 and K. Meisenheimer1

1  Max, Planck, Institut für Astronomie (MPIA), Königstuhl 17, 69117 Heidelberg, Germany
    e-mail: E.Thommes@thphys.uni-heidelberg.de
2  Institut für Theoretische Physik, Universität Heidelberg, Philosophenweg 16, 69120 Heidelberg, Germany

(Received 15 December 2003 / Accepted 1 October 2004)

Abstract
We present model calculations for the expected surface density of Ly- $\alpha$ emitting primeval galaxies (PGs) at high redshifts. We assume that elliptical galaxies and bulges of spiral galaxies (=spheroids) formed early in the universe and that the Ly- $\alpha$ emitting PGs are these spheroids during their first burst of star formation at high redshift. One of the main assumptions of the models is that the Ly- $\alpha$ bright phase of this first starburst in the spheroids is confined to a short period after its onset due to rapid formation of dust. The models do not only explain the failure of early surveys for Ly- $\alpha$ emitting PGs but are also consistent with the limits of new surveys (e.g. the Calar Alto Deep Imaging Survey - CADIS). At faint detection limits $S_{{\rm lim}} \le 10^{-20}$  W m -2 the surface density of Ly- $\alpha$ emitters is expected to vary only weakly in the redshift range between z=3 and z=6 with values > $10^3 / {\rm deg}^2 / \Delta z = 0.1 $ reaching its maximum at $z_0 \approx 4$. At shallower detection limits, $S_{{\rm lim}} \ge 3\times 10^{-20}$ W m -2 the surface density of high- z Ly- $\alpha$ emitters is expected to be a steep function of redshift and detection limit. This explains the low success in finding bright Ly- $\alpha$ galaxies at z > 5. We demonstrate how the observed surface densities of Ly- $\alpha$ emitting PGs derived from recent surveys constrain the parameters of our models. Finally, we discuss the possibility that two Ly- $\alpha$ bright phases occur in the formation process of galaxies: An initial - primeval - phase in which dust is virtually non-existant, and a later secondary phase in which strong galactic winds as observed in some Lyman break galaxies facilitate the escape of Ly- $\alpha$ photons after dust has already been formed.


Key words: galaxies: formation -- surveys -- galaxies: high-redshift -- X-ray: stars




© ESO 2005


What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.
  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.