DISCOVERY OF LYMAN BREAK GALAXIES AT z similar to 7 FROM THE zFourGE SURVEY Academic Article uri icon


  • 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 arcmin2 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 Hubble Space Telescope 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 broadband-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 (M UV -21.6 mag) from z 7 to z 5. Fitting the galaxies' spectral energy distributions, we predict Ly equivalent widths for the two brightest LBGs, and find that the presence of a Ly 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 broadband photometry. The derived specific star-formation rates for the bright LBGs are 13 Gyr-1, slightly higher than the lower-luminosity LBGs, implying that the star-formation rate increases with stellar mass for these galaxies. 2013. The American Astronomical Society. All rights reserved.

published proceedings


altmetric score

  • 0.5

author list (cited authors)

  • Tilvi, V., Papovich, C., Tran, K., Labbe, I., Spitler, L. R., Straatman, C., ... Willner, S. P.

citation count

  • 42

complete list of authors

  • Tilvi, V||Papovich, C||Tran, K-VH||Labbe, I||Spitler, LR||Straatman, CMS||Persson, SE||Monson, A||Glazebrook, K||Quadri, RF||van Dokkum, P||Ashby, MLN||Faber, SM||Fazio, GG||Finkelstein, SL||Ferguson, HC||Grogin, NA||Kacprzak, GG||Kelson, DD||Koekemoer, AM||Murphy, D||McCarthy, PJ||Newman, JA||Salmon, B||Willner, SP

publication date

  • April 2013