Lyα emission galaxies at a redshift of z ≈ 5.7 in the FORS deep field

¹ Landessternwarte Heidelberg-Königstuhl, 69117 Heidelberg, Germany e-mail: tapken@mpia.de
² Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
³ Universitäts-Sternwarte München, Scheinerstr. 1, 81679, München, Germany
⁴ Max-Planck-Institut für extraterrestrische Physik, Giessenbachstr., 85741 Garching, Germany

Received: 17 January 2006
Accepted: 22 March 2006

Abstract

Context.We present the results of a search for  emission galaxies at in the FORS Deep Field.

Aims.The objective of this study is to improve the faint end of the luminosity function of high-redshift emitting galaxies and to derive properties of intrinsically faint emission galaxies in the young universe.

Methods.Using FORS2 at the ESO VLT and a set of special interference filters, we identified candidates for high-redshift  galaxies. We then used FORS2 in spectroscopic mode to verify the identifications and to study their spectral properties.

Results.The narrow-band photometry resulted in the detection of 15 likely  emission galaxies. Spectra with an adequate exposure time could be obtained for eight galaxies. In all these cases the presence of  emission at was confirmed spectroscopically. The line fluxes of the 15 candidates range between 3  10^-21 W m^-2 and 16  10^-21 W m^-2, which corresponds to star-formation rates uncorrected for dust absorption between 1 and 5   yr^-1. The luminosity function derived for our photometrically identified objects extends the published luminosity functions of intrinsically brighter  galaxies.

Conclusions.With this technique the study of high-redshift  emission galaxies can be extended to low intrinsic luminosities.