MESMER: MeerKAT Search for Molecules in the Epoch of Reionization
  [Abridged] Observations of molecular gas at all redshifts are critical for
measuring the cosmic evolution in molecular gas density and understanding the
star-formation history of the Universe. The 12CO molecule (J=1-0 transition =
115.27 GHz) is the best proxy for extragalactic H2, which is the gas reservoir
from which star formation occurs, and has been detected out to z~6. Typically,
redshifted high-J lines are observed at mm-wavelengths, the most commonly
targeted systems exhibiting high SFRs (e.g. submm galaxies), and far-IR-bright
QSOs. While the most luminous objects are the most readily observed, detections
of more typical galaxies with modest SFRs are essential for completing the
picture. ALMA will be revolutionary in terms of increasing the detection rate
and pushing the sensitivity limit down to include such galaxies, however the
limited FoV when observing at such high frequencies makes it difficult to use
ALMA for studies of the large-scale structure traced out by molecular gas in
galaxies. This article introduces a strategy for a systematic search for
molecular gas during the EoR (z~7 and above), capitalizing on the fact that the
J=1-0 transition of 12CO enters the upper bands of cm-wave instruments at
high-z. The FoV advantage gained by observing at such frequencies, coupled with
modern broadband correlators allows significant cosmological volumes to be
probed on reasonable timescales. In this article we present an overview of our
future observing programme which has been awarded 6,500 hours as one of the
Large Survey Projects for MeerKAT, the forthcoming South African SKA pathfinder
instrument. Its large FoV and correlator bandwidth, and high-sensitivity
provide unprecedented survey speed for such work. An existing astrophysical
simulation is coupled with instrumental considerations to demonstrate the
feasibility of such observations and predict detection rates.
