64 radio telescopes come together to act as a single giant observatory

Located in the Northern Cape of South Africa, the MoreKAT telescope consists of 64 powerful radio antennas dedicated to investigating the mysteries of the universe. This facility is a precursor of the future Square kilometer array observatory (SKAO), which will consist of MeerKAT and the Hydrogen era of reionization array (HERA) in South Africa and the Australian SKA Pathfinder (QUESTION) and Murchison Radio Astronomy Observatory in Australia. A primary goal of the SKAO is to gain insight into the matter content of the universe and which mechanisms drive evolution and expansion.

The best way to do this is to observe the structure of the Universe on the largest scale, where astronomers can observe the distribution of galaxies, the nature of gravity and the role of dark matter and dark energy. To this end, an international team of astronomers combined the power of MeetKAT’s 64 radio telescopes to detect faint signatures of neutral hydrogen gas on cosmological scales. The resulting accuracy and sensitivity demonstrate what the SKAO will be able to achieve in the near future.

The findings of the international team are detailed in a recent article that: appeared online and was submitted for publication by the Monthly Notices from the Royal Astronomical Society† The team was led by Steven Cunnington of the Jodrell Bank Center for Astrophysics and including members of the South African Radio Astronomy Observatory (SARAO), the Shanghai Astronomical Observatorythe Istituto Nazionale di Fisica Nucleare (INFN), the Instituto de Astrofisica and Ciências do Espaçolthe NAOC-UKZN Computational Astrophysics Centerand several research institutes and universities.

A ‘radio-colored’ view of the sky above the Murchison Widefield Array radio telescope. Credit: Natasha Hurley-Walker (ICRAR/Curtin), GLEAM Team; ICRAR/Dr. John Goldsmith/Celestial Visions

Radio telescopes are extremely valuable when it comes to cosmology, the study of the origin, evolution and future of the universe. Radio telescopes in particular can detect radiation with a wavelength of 21 cm, a part of the radio spectrum generated by neutral hydrogen. As the most abundant element in the universe today, analyzing it in three dimensions allows astronomers to map the overall distribution of matter in the universe. It also penetrated the cosmos a few hundred thousand years after the Big Bang, when the first stars and galaxies were just beginning to form.

Due to the lack of visible light during this period, astronomers know it as the “Cosmic Dark Ages‘, which was expelled by the earliest galaxies about 1 billion years after the Big Bang. The study of neutral hydrogen at a wavelength of 21 cm will therefore allow astronomers to break through the veil of the “dark ages” and look at the galaxies we observe today. first come together† To achieve this feat, astronomers need radio antennas that combine immense power and sensitivity that can consistently track large areas of the night sky over time.

This is the purpose behind the SKAO, a next-generation array headquartered in Jodrell Bank in Cheshire, England. While it is still under construction, observatories such as MeerKAT are known as “precursor facilities” guiding the design of the SKAO. Combining the 64 arrays in a single-dish mode, MeerKAT will now act as an interferometer, combining several arrays of light from distant sources, acting as one giant telescope capable of producing images at much higher resolution. As Cunnington explained in a recent release from the University of Manchester:

“However, the interferometer will not be sensitive enough for the largest scales of most interest to cosmologists studying the universe. So instead, we’re using the array as a collection of 64 individual telescopes, allowing them to map the massive volumes of sky needed for cosmology.”

Composite image of the SKA combining all elements in South Africa and Australia. Credit: SKAO

As they point out in their paper, the new single-dish mode allowed the international team to create radio intensity maps on a cluster of galaxies recently studied by the WiggleZ research into dark energy – an optical survey of galaxies conducted by the Anglo-Australian Telescope between 2006 and 2011. Combining the data, they found a strong statistical correlation between the radio maps and the positions of the studied galaxies, demonstrating the MeerKAT’s ability to detect the large-scale cosmic structure and analyze the overall matter of the Universe. trace.

These findings were not only the first time such detections had been made using a multi-dish array (acting as separate telescopes), but also represent an important milestone in the development of the SKAO. As Cunnington revealed:

“This detection has been done with only a small amount of pilot survey data. It is encouraging to imagine what will be achieved as MeerKAT continues to make larger and larger observations. For years I have worked to predict the future capacity of the SKAO. To now reach a stage where we develop the tools we need and demonstrate their success with real data is incredibly exciting, and this marks just the beginning of what we hope will be a continuous showcase of results that advance our understanding of the Universe. .”

Read further: The University of Manchester

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