Astronomers connect 64 telescopes to observe the structure of the universe

space telescope

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An international team of astronomers has for the first time combined the power of 64 radio telescope dishes to detect the faint signatures of neutral hydrogen gas across cosmological scales.

The feat was accomplished with the South African-based MeerKAT telescope, a precursor to the world’s largest radio observatory, the SKA Observatory (SKAO), which will study the Universe in unprecedented detail.

A major goal of the SKAO is to understand the evolution and content of the universe and the mechanisms driving its accelerated expansion. One way to do this is to observe the structure of the universe at the largest scales. At these scales, entire galaxies can be viewed as discrete points, and analysis of their distribution provides clues to the nature of gravity and mysterious phenomena such as dark matter and dark energy.

Radio telescopes are a fantastic tool for this because they can detect radiation with wavelengths of 21 cm produced by neutral hydrogen, the most abundant element in the universe. By analyzing 3D maps of hydrogen spanning millions of light years, we study the overall distribution of matter in the universe.

Headquartered at Jodrell Bank, Cheshire, SKAO is currently under construction. However, Pathfinder telescopes already exist, such as the MeerKAT 64-dish array, to guide its design. MeerKAT is located in the Karoo Desert and is operated by the South African Radio Astronomy Observatory (SARAO). MeerKAT will eventually be part of the overall SKAO.

MeerKAT and SKAO will function primarily as interferometers, combining the array of dishes into a giant telescope capable of imaging distant objects with high resolution. “However, the interferometer will not be sensitive enough at the largest scales that are of interest to cosmologists studying the universe,” said co-lead author of the new research, Steven Cunnington. “So we’re using the array instead as a collection of 64 individual telescopes, allowing them to map the vast volumes of sky needed for cosmology.”

The single-dish mode of operation was advanced by a team from the University of the Western Cape, with several observations already made using MeerKAT. Many other institutions on four continents are involved in this ambitious project. In the new research, published and submitted for publication on arXiv, a team including Manchester-based astronomers Cunnington, Laura Wolz and Keith Grainge present the first-ever cosmological detection using this single-dish technique.

The new discovery is a common clustering pattern between MeerKAT’s maps and galaxy positions determined by the Anglo-Australian Optical Telescope. Because these galaxies are known to track all matter in the Universe, the strong statistical correlation between the radio maps and the galaxies indicates that the MeerKAT telescope is capturing large-scale cosmic structures. This is the first time such a detection has been performed using a multi-dish array acting as individual telescopes. The entire SKAO will be based on this technique and this therefore marks an important milestone in the roadmap for the cosmology science case with the SKAO.

“This discovery was made with 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 extensive observations.”

“I have been working on predicting the future performance of the SKAO for many years. To get to a stage now where we are developing the tools we need and demonstrating their success with real data is incredibly exciting. This marks just the beginning of what we hope will be an ongoing showcase of results that advance our understanding of the universe.”

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More information:
Steven Cunnington et al., HI intensity mapping with MeerKAT: power spectrum detection in cross-correlation with WiggleZ galaxies, arXiv:2206.01579 [astro-ph.CO]

Provided by the University of Manchester

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