A Limit on the Number Density of Bright z~7 Galaxies

TL;DR

This study constrains the abundance of bright galaxies at redshift around 7 by analyzing deep multiwavelength survey data, emphasizing the importance of infrared observations for accurate classification.

Contribution

It provides new upper limits on the number density of bright z~7 galaxies using a large, multi-field survey and highlights the necessity of infrared data for contaminant rejection.

Findings

Limits are consistent with existing z=6 luminosity functions.

Infrared data is crucial for classifying high-redshift galaxy candidates.

No significant excess of bright z~7 galaxies was found.

Abstract

We present a survey of bright optical dropout sources in two deep, multiwavelength surveys comprising eleven widely-separated fields, aimed at constraining the galaxy luminosity function at z~7 for sources at 5-10L*(z=6). Our combined survey area is 225 arcmin^2 to a depth of J=24.2 (AB, 3 sigma) and 135 arcmin^2 to J=25.3 (AB, 4 sigma). We find that infrared data longwards of 2 microns is essential for classifying optical dropout sources, and in particular for identifying cool Galactic star contaminants. Our limits on the number density of high redshift sources are consistent with current estimates of the Lyman break galaxy luminosity function at z=6.