  We present an investigation into the first 500 Myr of galaxy evolution from
the Cosmic Evolution Early Release Science (CEERS) survey. CEERS, one of 13
JWST ERS programs, targets galaxy formation from z~0.5 to z>10 using several
imaging and spectroscopic modes. We make use of the first epoch of CEERS NIRCam
imaging, spanning 35.5 sq. arcmin, to search for candidate galaxies at z>9.
Following a detailed data reduction process implementing several custom steps
to produce high-quality reduced images, we perform multi-band photometry across
seven NIRCam broad and medium-band (and six Hubble broadband) filters focusing
on robust colors and accurate total fluxes. We measure photometric redshifts
and devise a robust set of selection criteria to identify a sample of 26 galaxy
candidates at z~9-16. These objects are compact with a median half-light radius
of ~0.5 kpc. We present an early estimate of the z~11 rest-frame ultraviolet
(UV) luminosity function, finding that the number density of galaxies at M_UV ~
-20 appears to evolve very little from z~9 to z~11. We also find that the
abundance (surface density [arcmin^-2]) of our candidates exceeds nearly all
theoretical predictions. We explore potential implications, including that at
z>10 star formation may be dominated by top-heavy initial mass functions, which
would result in an increased ratio of UV light per unit halo mass, though a
complete lack of dust attenuation and/or changing star-formation physics may
also play a role. While spectroscopic confirmation of these sources is urgently
required, our results suggest that the deeper views to come with JWST should
yield prolific samples of ultra-high-redshift galaxies with which to further
explore these conclusions.
