Radio astronomy took another step forward recently, with the completion of Phase III of the Murchison Widefield Array (MWA) in Western Australia. We’ve reported before on how the MWA has investigated everything from SETI signals to the light from the earliest stars. WIth this upgrade, the MWA will continue to operate with much needed improvements while the radio astronomy awaits the completion of the successor it helped enable – the Square Kilometer Array (SKA).
MWA isn’t made up of a traditional dish like most radio observatories, but a series of small dipole antennas spread across a patch of the Outback of Western Australia, on land owned by the Wajarri Yamaji indigenous tribe. In Phase II, it held 4,096 antennas over an area covering around a 20 km2 circle.
The Phase III upgrade expanded the number of antennas, the telescope’s overall footprint, and the data processing capabilities. It doubled the number of antennas, bringing the total to 8,192. In doing so, it essentially doubled the raw collection power of the telescope itself.
Video explaining how the MWA receives and analyzes its signal.
In order to add that many antennas, it also expanded the footprint for the array out to 30 km2. This increased the “baseline” of the array, allowing it to achieve higher resolution on far away objects.
With all that additional data coming in, the engineers on the project had to upgrade the telescope’s “brains”. They added a new “correlator” – essentially a supercomputer responsible for combining the signals from each antenna into a coherent image, called MWAX. The combination of this improved correlator and increased number of antennas essentially quadrupled the telescope’s data output, allowing it to glean even more insights.
One of the primary focus areas for this effort was the Epoch of Reionization, a period in the early universe where neutral hydrogen dominated, and which can be probed using radio signals. However, it should also provide additional insights into transients and heliophysics that MWA had already excelled at. More data is always better, and this improvement will certainly provide more of that.
Dipole antenna “patch” of the MWA at night. Credit – John Goldsmith
One particularly interesting mystery the upgrade hopes to solve is that of Odd Radio Circles (ORCs). These faint radio sources had never been seen before, and we’re still not quite sure what they actually are, but one particularly interesting pair that seemed to be energized by a nearby galaxy. Since scientists don’t yet have an explanation for them, the improved MWA hopes to collect more data on them and potentially discover their cause.
Perhaps most importantly, it is priming researchers in the area for the completion of the SKA. The first phase of that project, while will be hosted in both Western Australia and South Africa. The Western Australian version, known as SKA-Low, will host an astonishing 131,000 dipole antennas, dwarfing even the impressive number in the MWA.
That project isn’t expected to be complete for another four years though, so for now MWA is the best radio telescope going in the area. With its $5.4 million upgrade complete, it will have a few more years in the spotlight before being eclipsed by the successor its research has helped enable.
Learn More:
Curtin University – MWA enters Phase III: A new era for WA’s window on the Universe
UT – Astronomers Are About to Detect the Light from the Very First Stars in the Universe
UT – Giant Low-Frequency Scan Searches for Aliens in 2,800 Galaxies