Photometric Selection of z~5 Lyman Break Galaxies in the ESO Remote Galaxy Survey

Abstract

We describe the selection of a sample of photometrically-defined Lyman break galaxies (LBGs) at z~5 using the multi-wavelength imaging data of the ESO Remote Galaxy Survey (ERGS). The data is drawn from ten widely-separated fields covering a total sky area of 275 arcmin squared. Starting with a simple colour (R-I>1.3) and magnitude (I<26.3) cut to isolate the Lyman break and then refining the sample by applying further optical and near-infrared photometric criteria we identify a sample of 253 LBG candidates. We carefully model the completeness of this sample and the factors that affect its reliability. There is considerable overlap between this sample and a spectroscopically-confirmed sample drawn from the same survey and this allows us to determine the reliability of the optical photometric selection (~60 per cent) and to show that the reliability can be significantly improved (to ~80 per cent) by applying near-infrared waveband criteria to exclude very red contaminants. Even this high level of reliability may compromise some statistical studies of LBG properties. We show that over 30 per cent of the highest reliability candidates have multiple UV-luminous components and/or disturbed morphology in HST imaging, though it is unclear whether this represents multiple interacting/merging sources or individual large sources with multiple UV bright regions. Using this sample we confirm that the normalisation of the bright end of the z=5 UV luminosity function (down to M*) is lower than the same at z=4 by a factor of 3. Using a Schechter fit we determine M*uv=-20.9+/-0.2. We discuss whether it is reasonable to expect the UV luminosity function to follow a Schechter function, given the UV emission is short-lived and stochastic, and does not necessarily trace the underlying mass of the galaxy.

15 pages, 13 figures, accepted for publication in MNRAS

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Cited by in corpus (16)

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• UV Luminosity Functions from 132 z~7 and z~8 Lyman-Break Galaxies in the ultra-deep HUDF09 and wide-area ERS WFC3/IR Observations
• Spectroscopic Confirmation of Three z-Dropout Galaxies at z = 6.844 - 7.213: Demographics of Lyman-Alpha Emission in z ~ 7 Galaxies
• Are z~5 QSOs found in the most massive high redshift over-densities?
• Observing the first galaxies
• Spectroscopy of z~5 Lyman Break Galaxies in the ESO Remote Galaxy Survey
• A resolved map of the infrared excess in a Lyman Break Galaxy at z=3
• Candidate Massive Galaxies at $z\sim 4$ in the Dark Energy Survey
• The detection of FIR emission from high redshift star-forming galaxies in the ECDF-S
• Establishing an analogue population for the most distant galaxies
• Limits on the Molecular Gas Content of z-5 LBGs
• Constraining the Thermal Dust Content of Lyman-Break Galaxies in an Overdense Field at z~5
• Limits on dust emission from z~5 LBGs and their local environments
• SED-inferred properties and morphology of Lyman-break galaxies at $z\sim 1$ in the CDF-S
• Detecting Massive Galaxies at High Redshift using the Dark Energy Survey
• Identifying clustering at high redshift through actively star-forming galaxies