The Precision Array to Probe the Epoch of Reionization

Cosmic reionization is the 'final frontier' in studies of cosmic
structure formation, corresponding to the epoch when light from the
first stars and black holes act to reionize the neutral intergalactic
medium, a few hundred million years after the Big Bang. I will present
a summary of the concept of reionization, and exciting recent results
that set the first constraints on the epoch of reionization. The
latest studies of spectra of the most distant quasars suggest a
substantial rise in the neutral fraction at z ~ 7. While
revolutionary, current measures of cosmic reionization have serious
limitations. The most direct probe of the neutral IGM during
reionization is through the 21cm emission line of hydrogen. I will
present the design and recent results from the Precision Array to
Probe the Epoch of Reionization. PAPER comprises two low frequency
dipole arrays (120 to 180 MHz) to study the HI 21cm signal from the
neutral IGM during reionization. Our design philosophy is to maintain
a simple telescope response in frequency and angle to mitigate the
substantial systematic problems that these measurements entail (strong
continuum foregrounds, very wide fields, large fractional bandwidths,
and strong terrestrial interference). I will present the first all-sky
images from our working arrays in the Karoo and Green Bank, details on
the processing involved, and plans for expansion to the full science
array.