2008ApJ...680L..97H

We report the discovery of a z∼9 Lyman break galaxy candidate, selected from the NICMOS Parallel Imaging Survey as a J-dropout with J₁₁₀-H₁₆₀=1.7. Spitzer/IRAC photometry reveals that the galaxy has a blue H₁₆₀-3.6 µm color and a spectral break between 3.6 and 4.5 µm. We interpret this break as the Balmer break and derive a best-fit photometric redshift of z∼9. We use Monte Carlo simulations to test the significance of this photometric redshift, and we show that there is a 96% probability of z≥7. We estimate that the lower limit to the comoving number density of such galaxies at z∼9 is φ>3.8x10^–6/Mpc3. If the high redshift of this galaxy is confirmed, this will indicate that the luminous end of the rest-frame UV luminosity function has not evolved substantially from z∼9 to z∼3. Still, some small degeneracy remains between this z∼9 model and models at z∼2-3; deep optical imaging (reaching I_AB∼29) can rule out the lower z models.