%0 Journal Article
%T Discovery of Lyman Break Galaxies at z~7 from the ZFOURGE Survey
%A V. Tilvi
%A C. Papovich
%A K. -V. H. Tran
%A I. Labbe
%A L. R. Spitler
%A C. M. S. Straatman
%A S. E. Persson
%A A. Monson
%A K. Glazebrook
%A R. F. Quadri
%A P. van Dokkum
%A M. L. N. Ashby
%A S. M. Faber
%A G. G. Fazio
%A S. L. Finkelstein
%A H. C. Ferguson
%A N. A. Grogin
%A G. G. Kacprzak
%A D. D. Kelson
%A A. M. Koekemoer
%A D. Murphy
%A P. J. McCarthy
%A J. A. Newman
%A B. Salmon
%A S. P. Willner
%J Physics
%D 2013
%I arXiv
%R 10.1088/0004-637X/768/1/56
%X Star-forming galaxies at redshifts z>6 are likely responsible for the reionization of the universe, and it is important to study the nature of these galaxies. We present three candidates for z~7 Lyman-break galaxies (LBGs) from a 155 arcmin^2 area in the CANDELS/COSMOS field imaged by the deep FourStar Galaxy Evolution (zFourGE) survey. The FourStar medium-band filters provide the equivalent of R~10 spectroscopy, which cleanly distinguishes between z~7 LBGs and brown dwarf stars. The distinction between stars and galaxies based on an object's angular size can become unreliable even when using HST imaging; there exists at least one very compact z~7 candidate (FWHM~0.5-1 kpc) that is indistinguishable from a point source. The medium-band filters provide narrower redshift distributions compared with broad-band-derived redshifts. The UV luminosity function derived using the three z~7 candidates is consistent with previous studies, suggesting an evolution at the bright end (MUV -21.6 mag) from z~7 to z~5. Fitting the galaxies' spectral energy distributions, we predict Lyman-alpha equivalent widths for the two brightest LBGs, and find that the presence of a Lyman-alpha line affects the medium-band flux thereby changing the constraints on stellar masses and UV spectral slopes. This illustrates the limitations of deriving LBG properties using only broad-band photometry. The derived specific star-formation rates for the bright LBGs are ~13 per Gyr, slightly higher than the lower-luminosity LBGs, implying that the star-formation rate increases with stellar mass for these galaxies.
%U http://arxiv.org/abs/1304.4227v1