Volume 402, Number 1, April IV 2003
|Page(s)||79 - 85|
|Published online||07 April 2003|
Constraints to the evolution of Ly-α bright galaxies between z = 3 and z = 6*
Max–Planck–Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
2 Insitut für Theoretische Physik, Universität Heidelberg, 69111 Heidelberg, Germany
3 Department of Physics, Denys Wilkinson Bldg., University of Oxford, Keble Road, Oxford, OX1 3RH, UK
Corresponding author: C. Maier, firstname.lastname@example.org
Accepted: 4 February 2003
Galaxies at high redshift with a strong Ly-α emission line trace massive star formation in the absence of dust, and can therefore be regarded as a prime signature of the first major starburst in galaxies. We report results of the Ly-α search within the Calar Alto Deep Imaging Survey (CADIS). With the imaging Fabry-Perot interferometer, CADIS can detect emission lines in three waveband windows free of night-sky emission lines at 700 nm, 820 nm, and 920 nm. The typical flux detection limit for Ly-α emission redshifted into these windows, , corresponds to (unobscured) star formation rates of /yr at . Candidate Ly-α-emitting galaxies are selected from the total emission line sample, which contains more than 97% of objects at , by the absence of flux below the Lyman limit (B-band “dropouts”), and the non-detection of secondary emission lines in narrow band filters. We have detected 5 bright Ly-α-emitting galaxy candidates at , and 11 candidates at . For two of four observed Ly-α candidates, one candidate at , and the other at , the emission line detected with the Fabry-Perot interferometer has been verified spectroscopically at the VLT. When compared to Ly-α surveys at , even the upper limits set by our list of candidates show that bright Ly-α galaxies are significantly rarer at than the assumption of a non-evolving population would predict. Therefore we conclude that the Ly-α bright phase of primeval star formation episodes reached its peak at redshifts .
Key words: galaxies: evolution / galaxies: formation / galaxies: high-redshift
© ESO, 2003
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