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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 448150.0, MPI für Astronomie / Publikationen_mpia
The building the bridge survey for z = 3 Lyα emitting galaxies. II. Completion of the survey
Authors:Grove, L. F.; Fynbo, J. P. U.; Ledoux, C.; Limousin, M.; Møller, P.; Nilsson, K. K.; Thomsen, B.
Date of Publication (YYYY-MM-DD):2009
Title of Journal:Astronomy and Astrophysics
Journal Abbrev.:A & A
Start Page:689
End Page:702
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:Context: We have substantial information about the kinematics and abundances of galaxies at z ≈ 3 studied in absorption against the light of background QSOs. At the same time we have already studied 1000s of galaxies detected in emission mainly through the Lyman-break selection technique; however, we know very little about how to make the connection between the two data sets. Aims: We aim at bridging the gap between absorption-selected and emission-selected galaxies at z ≈ 3 by probing the faint end of the luminosity function of star-forming galaxies at z ≈ 3. Methods: Narrow-band surveys for Lyman-alpha (Lyalpha) emitters have proven to be an efficient probe of faint, star-forming galaxies in the high-redshift universe. We performed narrow-band imaging in three fields with intervening QSO absorbers (a damped Lyalpha absorber and two Lyman-limit systems) using the VLT. We target Lyalpha at redshifts 2.85, 3.15, and 3.20. Results: We find a consistent surface density of about 10 Lyalpha-emitters per square arcmin per unit redshift in all three fields down to our detection limit of about 3×1041 erg s-1. The luminosity function is consistent with what has been found by other surveys at similar redshifts. About 85% of the sources are fainter than the canonical limit of R = 25.5 for most Lyman-break galaxy surveys. In none of the three fields do we detect the emission counterparts of the QSO absorbers. In particular we do not detect the counterpart of the z = 2.85 damped Lyalpha absorber towards Q2138-4427. This implies that the DLA galaxy is either not a Lyalpha emitter or is fainter than our flux limit. Conclusions: Narrow-band surveys for Lyalpha emitters are excellent for probing the faint end of the luminosity function at z ≈ 3. There is a very high surface density of this class of objects; yet, we only detect galaxies with Lyalpha in emission, so the density of galaxies with similar broad band magnitudes will be substantially higher. This is consistent with a very steep slope of the faint end of the luminosity function as has been inferred by other studies. This faint population of galaxies is playing a central role in the early Universe. There is evidence that this popualtion is dominating the intergrated star-formation activity, responsible for the bulk of the ionising photons at z ≳ 3 and likely also responsible for the bulk of the enrichment of the intergalactic medium. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, under programs 67.A-0033, 267.A-5704, 69.A-0380, 70.A-0048, and 072.A-0073.
Free Keywords:cosmology: observations; galaxies: quasars: individual: BRI 1346; galaxies: quasars: individual: BRI 1202-0725; galaxies: quasars: individual: Q 2138-4427; galaxies: high-redshift
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:URL:http://adsabs.harvard.edu/abs/2009A%26A...497..689... [ID No:1]
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