On Contamination and Completeness in z>5 Lyman Break Galaxy Surveys

Abstract

A large population of z>5 Lyman break galaxies has been identified in recent years. However, the high redshift galaxies selected by different surveys are subject to a variety of selection effects - some overt, others more subtle. We present an analysis of sample completeness and contamination issues in high redshift surveys, focusing on surveys at z=5 and using a spectroscopically-confirmed low redshift sample from the DEEP2 survey in order to characterise contaminant galaxies. We find that most surveys underestimate their contamination from highly clustered galaxies at z=1 and stars. We consider the consequences of this for both the rest-frame ultraviolet luminosity function and the clustering signal from z=5 galaxies. We also find that sources with moderate strength Lyman-alpha emission lines can be omitted from dropout surveys due to their blue colours, again effecting the derived luminosity functions. We discuss the points of comparison between different samples, and the applicability of survey-specific results to the population at z>5 in general.

Accepted for publication in MNRAS

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• A JWST/NIRCam Study of Key Contributors to Reionization: The Star-forming and Ionizing Properties of UV-faint $z\sim 7-8$ Galaxies
• A Flat Photoionization Rate at 2<z<4.2: Evidence for a Stellar-Dominated UV Background and Against a Decline of Cosmic Star Formation Beyond z~3
• A VLT/FORS2 view at $z\sim 6$: Lyman-$\alpha$ emitter fraction and galaxy physical properties at the edge of the epoch of cosmic reionization
• A High Space Density of Luminous Lyman Alpha Emitters at z~6.5
• Large-scale environment of z~5.7 CIV absorption systems I: projected distribution of galaxies
• Characterization and modeling of contamination for Lyman break galaxy samples at high redshift
• Applications of Stellar Population Synthesis in the Distant Universe
• SkyHopper mission science case I: Identification of high redshift Gamma-Ray Bursts through space-based near-infrared afterglow observations
• A novel analysis of contamination in Lyman-break galaxy samples at $\mathbf{z}\sim 6-8$: spatial correlation with intermediate-redshift galaxies at $\mathbf{z}\sim 1.3-2$