2 minute read
The two low frequency precursors
Murchison Widefield Array
Made up of 8,192 antennas spread over more than 30 square kilometres on Wajarri Yamaji Country, the Murchison Widefield Array is the longest-running SKA precursor led by Curtin University on behalf of an international collaboration.
The MWA allows astronomers to explore the low-frequency Universe in extraordinary detail and has produced research that has paved the way for the SKA-Low telescope.
The GaLactic and Extragalactic All-Sky MWA survey, or GLEAM, is one of the largest sky surveys of all time, covering 90% of the southern sky. It created the first radio colour panorama of the Universe, combining observations across 20 frequencies to map the sky in unprecedented detail and served as a crucial stepping stone for calibrating the SKA-Low telescope.
The Hydrogen Epoch of Reionisation Array
BY DR JOSH DILLON, UNIVERSITY OF CALIFORNIA, BERKELEY
The Hydrogen Epoch of Reionisation Array (HERA), an SKA-Low precursor telescope located in South Africa’s Karoo, is an interferometer designed to detect hydrogen during the so-called Cosmic Dawn. This period saw the formation of the first stars, black holes, and galaxies, which ionised all the gas between galaxies within the first billion years after the Big Bang some 13 billion years ago.
Designed by engineers from the University of California, Berkeley, in the USA, and from SARAO, and constructed by local crews, HERA is one of the world’s largest radio telescopes, boasting over 50,000 m2 of collecting area. That size is enabled by HERA’s low observing frequency (50 to 250 MHz, or 1- to 6-m wavelengths), where ordinary wire mesh behaves like a mirror.
Early HERA results lead the world in sensitivity, already ruling out some proposed models of reionisation. The team is now analysing petabytes of HERA data – enough to make a first detection of the high-redshift 21-cm signal and inaugurate a new era in radio astronomy and cosmology.
