Astronomy Colloquium

Cosmic reionization corresponds to the epoch when light from the first stars and black holes reionized the neutral InterGalactic Medium (IGM) that pervade the Universe following recombination. This epoch of 'first new light' in the Universe, remains the last epoch of cosmic structure formation to be tested and explored.  I will summarize the latest constraints on cosmic reionization, with a focus on observations of the Gunn-Peterson effect in the spectra of the highest z quasars (z > 6), and related techniques. I will then focus on the PAPER experiment to detect HI 21cm emission directly from the neutral IGM at low frequencies (120MHz to 180MHZ). PAPER has produced unprecedented wide field, low frequency images of the southern sky, and we have set the best (statistical) limits on the HI 21cm signal from reionization to date.  I will conclude by presenting plans for the Hydrogen Epoch of Reionization Array, a 568 element array in South Africa that will provide a detailed characterization of the HI 21cm power spectrum and its evolution, as well as the potential for direct imaging of the largest scale structures during reionization.