ASKAP radio array in Australia maps 1 million new galaxies in 300 hours of observation
With just a few weeks of observations, a revolutionary census of the observable Universe in radio wavelengths was conducted and a million new galaxies revealed.
The Australian Square Kilometre Array Pathfinder (ASKAP) is a 36 12-m antenna radio observatory, operated by the Commonwealth Scientific and Industrial Research Organisation (CSIRO). Before this all-sky survey, it has mainly been used to detect radio bursts: these reach the antennas at an ever-so slightly different time, which enables astronomers to determine their location. The origin of some of those bursts is unknown, theories range from alien civilizations to magnetar outbursts – a magnetar is a neutron star with a strong magnetic field. ASKAP has also detected the so called “Odd radio circles”, a recently discovered and yet unaccounted for phenomenon, depicted below.
Now for the first time, the whole power of the observatory has been used to look at about 83% of the whole observable Universe, in an effort known as the Rapid ASKAP Continuum Survey (RACS). This represents over 3 million galaxies, and the ASKAP mapping has revealed 1 million which hadn’t been observed before. As you can imagine, such an all-sky survey generates a lot of data. And by a lot, I mean 13.5 exabytes - a laptop typically has up to 64 gigabytes of memory, so this is of the order of 108 , i.e. a one followed by eight zeroes, times more. The data was processed by a CSIRO software in a supercomputing facility to yield a set of 903 images, each containing 70 billion pixels (when an HD camera contains a few hundred million). These were then combined together to form this “Google Maps” of galaxies, as the map has been nicknamed.
Made publicly available by the CSIRO, it will be an unmatched resource for astrophysicists around the world to understand the Universe’s structure and evolution in terms of both the quality and quantity of the data. Thanks to the latter, statistical analysis methods can be used, which was much more complicated with the less comprehensive results beforehand. In fact, previous all-sky surveys have taken years to complete and were about twice less precise, but what’s truly unique about this census is that it only took 300 hours of observation.
The Square Kilometre Array, which is due to be completed during this decade, will combine radio telescopes in South Africa and Australia and will be able to observe an even more incredible number of galaxies in a short period of time. According to CSIRO astronomer David McConnell, “We expect to find tens of millions of new galaxies in future surveys”.
Cover Image: CSIRO
Image credits:
1- ORC1, Bärbel Koribalski, based on ASKAP data
2- CSIRO
