Second Data Release of the COSMOS Lyman-alpha Mapping and Tomographic
  Observation: The First 3D Maps of the Large-Scale Cosmic Web at 2.05<z<2.55
  We present the second data release of the COSMOS Lyman-Alpha Mapping And
Tomography Observations (CLAMATO) Survey conducted with the LRIS spectrograph
on the Keck-I telescope. This project used \lyaf{} absorption in the spectra of
faint star forming galaxies and quasars at z~ 2-3 to trace neutral hydrogen in
the intergalactic medium. In particular, we use 377 objects over a footprint of
~0.2 deg^2 to reconstruct the absorption field at 2.05 < z < 2.55. We apply a
Wiener filtering technique to the observed data to reconstruct three
dimensional maps of the field over a volume of 4.1 x 10^5 (h^{-1} Mpc)^3. In
addition to the filtered flux maps, for the first time we infer the underlying
dark matter field through a forward modelling framework from a joint likelihood
of galaxy and \lyaf{} data, finding clear examples of cosmic voids, filaments,
and nodes. This work constitutes the highest redshift identification of the
large scale cosmic web. In addition to traditional figures, we present a number
of interactive three dimensional models to allow exploration of the data and
qualitative comparisons to known galaxy surveys. We find that our inferred
over-densities are consistent with those found from galaxy fields. We will make
all our reduced spectra, extracted Lyman-alpha forest pixel data, and
reconstructed tomographic maps available publicly upon publication.
