Looking Deeper Into the Big Bang – The Murchison Widefield Array

For the last 13.7 billion years the Universe has been expanding, but for the first 400 million years of its existence, our Universe looked nothing like it does today.

Immediately after the Big Bang, the Universe was a rapidly expanding hadean mixture of ionized gas. For the next 400 million years the Universe cooled steadily and electrons and proton began to combine to form hydrogen.

Sometime around 13.3 billion years ago, galaxies and quasars began to form in the Universe. This era, which lasted somewhere on the order of 1 billion years, is known as the Epoch of Reionization. Scientists have been interested in this period of the Universes’ history because it holds much of the information about the formation of the earliest galaxies and stars. However, looking that far back into the Universe’s past presents scientists with a problem. Visible light radiating from the Universe’s earliest objects has faded so completely that one of the only known ways to detect these objects is to look for their electro-magnetic signatures. To do this astronomers use radio telescopes.

A radio telescope is a directional radio antenna that monitors the radio frequency portion of the electro-magnetic spectrum. Similar to the visible light spectrum, the radio spectrum contains information that can be used to determine the chemical composition and relative position of objects that can no longer be seen in the visible spectrum.

If you were to take an 800km trip northwest of Perth, Australia you’d find yourself in the middle of the outback. In an area about the size of the Netherlands, the University of Western Australia, operates the Murchison Widefield Array (MWA) a large radio telescope. Tucked away from any possible radio interference, the MWA may uncover some of the Universe’s oldest secrets.

The MWA is described as “a radically new type of radio telescope, with no moving parts, and dependent on prodigious computer power to create exquisite real-time wide-field images of the radio sky…[T]he MWA will observe with unprecedented sensitivity to discover low-frequency radio phenomena that have never been seen before.” It’s been built by an international collaboration between partners in Australia, India, New Zealand and the U.S.

The MWA is comprised of 128 phased tiles of 16 crossed dipoles. The 128 tiles are spread across a region of 1.5km in the heart of the outback. According to Wikipedia each tile is “comprise[d of a] four by four regular grid of dual-polarisation dipole elements arranged on a 4m x 4m steel mesh ground plane… Signals from each dipole pass through a low noise amplifier (LNA) and are combined in an analogue beamformer to produce tile beams on the sky… The radio frequency (RF) signals for the tile-beams are transmitted to a receiver, each receiver being able to process the signals from a group of eight tiles.” This signal is then transmitted to the CSIRO Data Processing Facility where it is analyzed.

One of the goals of the MWA is to look deep into the Universes’ past to give scientists a better understanding of what was happening during the Epoch or Reionization. Currently the MWA is only operating at partially capacity but even at its current strength the MWA is delivering results that equal all previous efforts to map the early Universe. By 2013 the MWA will be at full capacity and researchers predict that it will produce results 10 times better than its current capabilities.