Illuminating our Early Universe with HERA, the Hydrogen Epoch of Reionization Array

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The objective of this program is to build a large array of low frequency radio antennas to study neutral hydrogen emission emitted at a frequency of 1420 MHz. This emission originated during the "epoch of reionization," when the universe transitioned from being predominantly neutral gas to being highly ionized. HERA, the Hydrogen Epoch of Reionization Array, will consist of 240 14-m parabolic dishes operating at observing frequencies from 50 to 250 MHz at the South African Square Kilometer Array site. HERA will be sensitive to hydrogen at great distances, shifted downward in radio frequency by the expansion of the universe. Broader impacts of the work include training of undergraduate and graduate students, and increased participation of underrepresented minorities in STEM research. The program for underrepresented minorities has two elements: an annual 10-week summer research program involving undergraduates and graduate students from the US and South Africa working on HERA science, and a series of training workshops for high school teachers with the involvement of the undergraduates.The HERA project will attempt to make the first detection of the distribution of the neutral Intergalactic Medium (IGM) between redshifts z=6-12 at the end of the epoch of reionization, possibly extending to z=30 if the required sensitivity at a frequency of 50 MHz is achieved. This will enable the three dimensional power-spectrum of the 21cm hydrogen line from the primordial IGM to be established. Eventually HERA is expected to image the bubbles of ionized gas expanding out from newly formed galaxies and quasars.