Abstract

We identify four unusually bright (H-160,H-AB 25.5) galaxies from Hubble Space Telescope (HST) and Spitzer CANDELS data with probable redshifts z similar to 7-9. These identifications include the brightest-known galaxies to date at z greater than or similar to 7.5. As Y-band observations are not available over the full CANDELS program to perform a standard Lyman-break selection of z > 7 galaxies, we employ an alternate strategy using deep Spitzer/IRAC data. We identify z similar to 7.1-9.1 galaxies by selecting z greater than or similar to 6 galaxies from the HST CANDELS data that show quite red IRAC [3.6]-[4.5] colors, indicating strong [O III]+ H beta lines in the 4.5 mu m band. This selection strategy was validated using a modest sample for which we have deep Y-band coverage, and subsequently used to select the brightest z. 7 sources. Applying the IRAC criteria to all HST-selected optical dropout galaxies over the full similar to 900 arcmin(2) of the CANDELS survey revealed four unusually bright z similar to 7.1, 7.6, 7.9, and 8.6 candidates. The median [3.6]-[4.5] color of our selected z similar to 7.1-9.1 sample is consistent with rest-frame [O III]+ H beta EWs of similar to 1500 angstrom in the [4.5] band. Keck/MOSFIRE spectroscopy has been independently reported for two of our selected sources, showing Ly alpha at redshifts of 7.7302 +/- 0.0006 and 8.683(-0.004)(+0.001), respectively. We present similar Keck/MOSFIRE spectroscopy for a third selected galaxy with a probable 4.7 sigma Ly alpha line at z(spec) = 7.4770 +/- 0.0008. All three have H-160-band magnitudes of similar to 25 mag and are similar to 0.5 mag more luminous (M-1600 similar to -22.0) than any previously discovered z similar to 8 galaxy, with important implications for the UV luminosity function (LF). Our three brightest and highest redshift z > 7 galaxies all lie within the CANDELS-EGS field, providing a dramatic illustration of the potential impact of field-to-field variance.