Z > 7 galaxies with red Spitzer/IRAC [3.6]-[4.5] colors in the full
  CANDELS data set: the brightest-known galaxies at Z ~ 7-9 and a probable
  spectroscopic confirmation at Z=7.48
  We identify 4 unusually bright (H < 25.5) galaxies from HST and Spitzer
CANDELS data with probable redshifts z ~ 7-9. These identifications include the
brightest-known galaxies to date at z > 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 ~ 7.1 - 9.1 galaxies by selecting z >~ 6
galaxies from the HST CANDELS data that show quite red IRAC [3.6]-[4.5] colors,
indicating strong [OIII]+Hbeta lines in the 4.5 micron 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
~900 arcmin**2 of the CANDELS survey revealed four unusually bright z ~ 7.1,
7.6, 7.9 and 8.6 candidates. The median [3.6]-[4.5] color of our selected z ~
7.1-9.1 sample is consistent with rest-frame [OIII]+Hbeta EWs of ~1500A, 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^+0.001_-0.004, respectively. We present similar Keck/MOSFIRE spectroscopy
for a third selected galaxy with a probable 4.7sigma Ly-alpha line at
z_spec=7.4770+/-0.0008. All three have H-band magnitudes of ~25 mag and are
~0.5 mag more luminous (M(UV) ~ -22.0) than any previously discovered z ~ 8
galaxy, with important implications for the UV LF. Our 3 brightest, 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.
