Astronomers will combine 64 radio telescope dishes in order to observe elusive cosmic structures in deep space.
An international team of astronomers has combined 64 radio telescope dishes to detect the faint signatures of neutral hydrogen gas across the entire cosmological scale for the first time.
This feat has been accomplished with the MeerKAT telescope based in South Africa, the precursor to the SKA Observatory (SKAO), the world’s largest radio observatory.
SKAO aims to gain an understanding of the evolution and content of the Universe as well as the mechanisms driving its accelerated expansion. We can do this by studying the structure of the Universe on the largest scale.
Galaxies can be viewed as singular points at these scales. An analysis of their distribution can provide clues to gravitational science and the mysterious nature of dark matter and energy.
A radio telescope is a great instrument for this as it can detect radiation at 21cm wavelengths, which is generated by neutral hydrogen, the most abundant element in the Universe. The total distribution of matter in the Universe is mapped by analyzing 3D maps of hydrogen spanning millions of light-years.
The SKAO is currently under construction at its headquarters in Jodrell Bank, Cheshire. The 64-dish array MeerKAT, for example, is already serving as a pathfinder telescope for its design. MeerKAT will eventually become part of the South African Radio Astronomy Observatory (SKAO) based in the Karoo Desert.
Both MeerKAT and SKAO are intended to be operated as interferometers, whereby the array of dishes will act as one giant telescope capable of taking high-resolution images of distant objects.
“However, the interferometer will not be sensitive enough to the largest scales most interesting for cosmologists studying the Universe.” explained the co-lead author of the new research paper, Steven Cunnington.
“Therefore, we instead use the array as a collection of 64 individual telescopes, which allows them to map the giant volumes of sky required for cosmology.”
Several observations have already been conducted with MeerKAT in a single-dish mode by a team at the University of the Western Cape.
Many other institutions are involved in this ambitious project. Researchers Steven Cunnington, Laura Wolz, and Keith Grainge from the University of Manchester recently released new research on arXiv and submitted for publication. In the paper, they present the first-ever cosmological detection using this technique.
A shared clustering pattern has been found between MeerKAT’s maps and galaxies that have been located by the optical Anglo-Australian Telescope. As galaxies are known to trace the overall matter of the Universe, we can conclude that the MeerKAT telescope is detecting large-scale cosmic structures by measuring the strong statistical correlation between the radio maps and the galaxies.
It is the first time a multi-dish array has been used as individual telescopes to make such an observation. The full SKAO will rely on this technique, and this represents an extremely meaningful milestone in the cosmology science case that will be incorporated into the SKAO.
“This detection was made with just a small amount of pilot survey data,” revealed Steven Cunnington. “It’s encouraging to imagine what will be achieved as MeerKAT continues to make increasingly larger observations.
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