Cassata, P. and Capak, P. and Scoville, N. (2015) The VIMOS Ultra-Deep Survey (VUDS): fast increase in the fraction of strong Lyman-α emitters from z = 2 to z = 6. Astronomy and Astrophysics, 573 . Art. No. A24. ISSN 0004-6361. http://resolver.caltech.edu/CaltechAUTHORS:20150324-120025853
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Aims. The aim of this work is to constrain the evolution of the fraction of strong Lyα emitters among UV selected star-forming galaxies at 2 <z< 6, and to measure the stellar escape fraction of Lyα photons over the same redshift range. Methods. We exploit the ultradeep spectroscopic observations with VIMOS on the VLT collected by the VIMOS Ultra-Deep Survey (VUDS) to build an unique, complete, and unbiased sample of ~4000 spectroscopically confirmed star-forming galaxies at 2 <z< 6. Our galaxy sample includes UV luminosities brighter than M^*_(FUV) at 2 <z< 6, and luminosities down to one magnitude fainter than M^*_(FUV) at 2 <z< 3.5. Results. We find that 80% of the star-forming galaxies in our sample have EW_0(Lyα) < 10 Å, and correspondingly f_(esc)(Lyα) < 1%. By comparing these results with the literature, we conclude that the bulk of the Lyα luminosity at 2 <z< 6 comes from galaxies that are fainter in the UV than those we sample in this work. The strong Lyα emitters constitute, at each redshift, the tail of the distribution of the galaxies with extreme EW_0(Lyα) and f_(esc)(Lyα). This tail of large EW_0(Lyα) and f_(esc)(Lyα) becomes more important as the redshift increases, and causes the fraction of strong Lyα with EW_0(Lyα) > 25 Å to increase from ~5% at z ~ 2 to ~30% at z ~ 6, with the increase being stronger beyond z ~ 4. We observe no difference, for the narrow range of UV luminosities explored in this work, between the fraction of strong Lyα emitters among galaxies fainter or brighter than M^*_(FUV), although the fraction for the faint galaxies evolves faster, at 2 <z< 3.5, than for the bright ones. We do observe an anticorrelation between E(B − V) and f_(esc)(Lyα): generally galaxies with high fesc(Lyα) also have small amounts of dust (and vice versa). However, when the dust content is low (E(B − V) < 0.05) we observe a very broad range of f_(esc)(Lyα), ranging from 10-3 to 1. This implies that the dust alone is not the only regulator of the amount of escaping Lyα photons.
|Additional Information:||© 2014 ESO. Received 17 March 2014. Accepted 15 September 2014. Published online 09 December 2014. Based on data obtained with the European Southern Observatory Very Large Telescope, Paranal, Chile, under Large Program 185.A-0791. We thank ESO staff for their continuous support for the VUDS survey, particularly the Paranal staff conducting the observations and Marina Rejkuba and the ESO user support group in Garching. This work is supported by funding from the European Research Council Advanced Grant ERC-2010-AdG-268107-EARLY and by INAF Grants PRIN 2010, PRIN 2012 and PICS 2013. A.C., O.C., M.T. and V.S. acknowledge the grant MIUR PRIN 2010–2011. D.M. gratefully acknowledges LAM hospitality during the initial phases of the project. This work is based on data products made available at the CESAM data center, Laboratoire d’Astrophysique de Marseille. This work partly uses observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l’Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at TERAPIX and the Canadian Astronomy Data Centre as part of the Canada-France-Hawaii Telescope Legacy Survey, a collaborative project of NRC and CNRS.|
|Subject Keywords:||galaxies: evolution, galaxies: formation, galaxies: high-redshift, galaxies: fundamental parameters, cosmology: observations|
|Official Citation:||The VIMOS Ultra-Deep Survey (VUDS): fast increase in the fraction of strong Lyman-α emitters from z = 2 to z = 6 P. Cassata, L. A. M. Tasca, O. Le Fèvre, B. C. Lemaux, B. Garilli, V. Le Brun, D. Maccagni, L. Pentericci, R. Thomas, E. Vanzella, G. Zamorani, E. Zucca, R. Amorin, S. Bardelli, P. Capak, L. P. Cassarà, M. Castellano, A. Cimatti, J. G. Cuby, O. Cucciati, S. de la Torre, A. Durkalec, A. Fontana, M. Giavalisco, A. Grazian, N. P. Hathi, O. Ilbert, C. Moreau, S. Paltani, B. Ribeiro, M. Salvato, D. Schaerer, M. Scodeggio, V. Sommariva, M. Talia, Y. Taniguchi, L. Tresse, D. Vergani, P. W. Wang, S. Charlot, T. Contini, S. Fotopoulou, A. M. Koekemoer, C. López-Sanjuan, Y. Mellier and N. Scoville A&A 573 A24 (2015) DOI: http://dx.doi.org/10.1051/0004-6361/201423824|
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|Deposited By:||Ruth Sustaita|
|Deposited On:||24 Mar 2015 19:32|
|Last Modified:||13 Jul 2015 15:02|
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