An international team of astronomers has for the first time combined the power of 64 radio telescope dishes to detect faint signals of neutral hydrogen gas across cosmic scales.
The feat was achieved using the South African-based MeerKAT telescope, a precursor to the world’s largest radio observatory, the SKA Observatory (SKAO), which will probe the universe in unprecedented detail.
SKAO’s primary goal is to understand the evolution and content of the universe along with the mechanisms that drive its accelerating expansion. One way to achieve this is by observing the structure of the universe on the largest scales. At these scales, entire galaxies can be thought of as single points, and analysis of their distribution reveals clues about the nature of gravity and mysterious phenomena such as dark matter and dark energy.
Radio telescopes are a great tool for that as they can detect radiation at wavelengths of 21 centimeters from neutral hydrogen, the most abundant element in the universe. By analyzing 3D maps of hydrogen spanning millions of light years, we probe the overall distribution of matter in the universe.
SKAO, which is headquartered in Jodrell Bank, Cheshire, is currently under construction. However, there are already Pathfinder telescopes, such as the MeerKAT Array 64, to guide their design. Headquartered in the Karoo Desert and operated by the South African Radio Astronomy Observatory (Sarao), Meerkat will eventually become part of the full SKAO.
MeerKAT and SKAO will essentially act as interferometers, combining the dish array as a single giant telescope capable of imaging distant objects with high resolution. “However, the interferometer will not be sensitive enough to the largest, most exciting scales for cosmologists studying the universe,” explained co-lead author of the new research paper, Stephen Cannington. “So instead, we’re using the array as a group of 64 individual telescopes allowing them to map the gigantic sky volumes required for cosmology.”
The single-dish operating method was prompted by a team from the University of the Western Cape, with several observations already made using MeerKAT. This ambitious project includes many other institutions spanning four continents. In new research released by arXiv and submitted for publication, a team including astronomers from Manchester Cannington, Laura Walls and Keith Gring made the first-ever cosmic discovery using the single-dish technology.
The new discovery is a common aggregation pattern between MeerKAT maps and the locations of galaxies determined by the Anglo-Australian Optical Telescope. Since these galaxies are known to track the total matter of the universe, the strong statistical correlation between radio maps and galaxies shows that the MeerKAT telescope detects a large-scale cosmic structure. This is the first time this discovery has been made using a multi-plate array that operates as individual telescopes. The entire SKAO will rely on this technology, and thus this represents an important milestone in the roadmap for the state of cosmology with SKAO.
“This discovery was made using only a small amount of pilot survey data,” Cunnington revealed. “It is encouraging to imagine what will be achieved as MeerKAT continues to make increasingly larger observations.”
“I’ve been working for many years to predict the future ability of SKAO. Getting now to a point where we are developing the tools we need and demonstrating their success with real data is very exciting. And this is only the beginning of what we hope will be an ongoing demonstration of results that advance our understanding of the universe.”
Astronomers discover a galactic space laser
Steven Cunnington et al, High Density Mapping Using MeerKAT: Discovery of the Energy Spectrum in Cross Correlation with WiggleZ Galaxies, arXiv: 2206.01579 [astro-ph.CO]arxiv.org/abs/2206.01579
Presented by the University of Manchester
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