2003/12/14 by E. Thommes, Thommes, E., K. Meisenheimer +1
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics (astro-ph) #FOS: Physical sciences #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0312363
18 pages, 12 figures, submitted to Astronomy & Astrophysics
openalex publication_date 2003/12/14 · arxiv created 2004/11/19 · arxiv updated 2009/12/01 · openalex created_date 2024/04/11 · openalex updated_date 2026/07/28
We present model calculations for the expected surface density of Ly-α 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-α 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-α 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-α 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 Slim ≤ 10-20W/m2 the surface density of Ly-α emitters is expected to vary only weakly in the redshift range between z=3 and z=6 with values > 103 / deg2 / Δz = 0.1 reaching its maximum at z0 ≈ 4. At shallower detection limits, Slim ≥ 3× 10-20W/m2 the surface density of high-z Ly-α emitters is expected to be a steep function of redshift and detection limit. This explains the low success in finding bright Ly-α galaxies at z > 5. We demonstrate how the observed surface densities of Ly-α emitting PGs derived from recent surveys constrain the parameters of our models. Finally, we discuss the possibility that two Ly-α bright phases occur in the formation process of galaxies: An initial -- primeval -- phase in which dust is virtually non-existing, and a secondary later phase in which strong galactic winds as observed in some Lyman break galaxies facilitate the escape of Ly-α photons after dust has already been formed.