One of the great triumphs of modern science is our understanding of the Universe as an evolving single entity in its own right.  At some point in its cosmic journey, the Universe evolved structures that are its current denizens:  stars, galaxies, black holes and so on.  The era when this happened in the Universe was sometime in its first billion years of existence.  We have detected a few of the "monsters" from around this epoch, but the shape and scope of this rise of structure has not been measured and understood.  Ours is a project to build a telescope that can see this period with some clarity and explain the rise of the first structures that shone in the Universe.  These shining structures energized the neutral gas that inhabited the space between them producing a cosmic phase change reionizing this intergalactic medium.  We have dubbed this period the Epoch of Reionization, or EOR.  The bulk of the neutral gas is hydrogen and so we have named our Telescope the Hydrogen Epoch of Reionization Array (HERA).  Details may be found in an eponymous recent paper in March 2017 issue of the Publications of the Astronomical Society of the Pacific (http://iopscience.iop.org/article/10.1088/1538-3873/129/974/045001/meta).

Hydrogen gas makes up the vast bulk of the tenuous material between the stars and galaxies.  In its neutral state hydrogen is measurable via a spectral line with a wavelength of 21cm.  This gives us an invaluable way to see a large part of the Universe.  The intergalactic medium was in this neutral state from about 380,000 years after the Big Bang (an event measured by observing the Cosmic Microwave Background) to the EOR -- a period we are trying to detect and characterize.  We measure it by observing the neutral gas via the 21-cm line as it is being "consumed" by reionization.  As we look back in time, the expanding nature of the Universe stretches this wavelength such that we now look for this line near the FM radio band.  Taking all of this together, we can measure and quantify the state of the Universe throughout this entire period of evolution.

Since we are looking in the radio band, we are building a radio telescope tuned to carefully measure electromagnetic energy in the radio band.  Since the signal is very weak, we need a big telescope.  Given our ability to accurately digitally handle the signals at this wavelength, it is actually much better for us to build many smaller telescopes and use them as a single large telescope.  Hence we have an "array" of telescopes.  Since humanity's day-to-day technology produces copious amounts of signals in this band, we are building HERA in the remote region of the Northern Cape of South Africa, in the Karoo Desert to get away from this "radio pollution".

This three-year project has funded the initial design and development of the technology for this array, and has funded the construction of the first 19 elements in the Karoo.  The key deliverables of this project were 1) to develop a dish design that is capable of supporting the target science, 2) to develop metrics by which to measure the performance of these dishes and to validate their appropriateness for this project, and 3) to prototype the most promising design in a small array to begin building the infrastructure an analysis needed for a larger project.  We have successfully completed all of these key outcomes, and with subsequent funding, we are building HERA out to 350 elements.  These antennas all sit next to one another, so we have a dense field of telescopes.  The attached images show a picture of the 19 elements funded under this program and an artist's conception of the full array when complete in 2019.

Last Modified: 12/18/2017
Modified by: Aaron R Parsons