A Systematic Search for Lensed High-Redshift Galaxies in HST Images of
  MACS Clusters
  We present the results of a 135-arcmin$^2$ search for high-redshift galaxies
lensed by 29 clusters from the MAssive Cluster and extended MAssive Cluster
Surveys (MACS and eMACS). We use relatively shallow images obtained with the
Hubble Space Telescope in four passbands, namely, F606W, F814W, F110W, and
F140W. We identify 130 F814W dropouts as candidates for galaxies at $z \le 6$.
In order to fit the available broad-band photometry to galaxy spectral energy
distribution (SED) templates, we develop a prior for the level of dust
extinction at various redshifts. We also investigate the systematic biases
incurred by the use of SED-fit software. The fits we obtain yield an estimate
of 20 Lyman-break galaxies with photometric redshifts from $z \sim 7$ to 9. In
addition, our survey has identified over 100 candidates with a significant
probability of being lower-redshift ($z \sim 2$) interlopers. We conclude that
even as few as four broad-band filters -- when combined with fitting the SEDs
-- are capable of isolating promising objects. Such surveys thus allow one both
to probe the bright end ($M_{1500} \le -19$) of the high-redshift UV luminosity
function and to identify candidate massive evolved galaxies at lower redshifts.
