We have discovered three robust candidate galaxies at redshift z~7 using deep near-infrared imaging from the ZFOURGE survey in the CANDELS/COSMOS field. The FourStar medium-band filters provide the equivalent of R∼10 spectroscopy, which cleanly distinguishes between z ∼ 7 galaxies and nearby brown dwarfs.
FourStar medium-band filters provides a powerful tool to distinguish between compact galaxies and nearby Tdwarfs. Left: spectral energy distribution of a compact z~7 candidate galaxy. Right: A nearby Tdwarf, mimicking colors of a z~7 galaxy, fitted with a T7 template spectrum.
UV luminosity function of galaxies at z~7. Our observations show a moderate evolution at the bright end of the luminosity function, consistent with previous studies.