American astronomers have detected a signal from the first stars to have emerged in the early universe about 180 million years after the Big Bang — using a small radio telescope at a CSIRO observatory in Western Australia.
Dr. Judd Bowman of Arizona State University has been running his ‘Experiment to Detect the Global EoR (Epoch of Reionization) Signature (EDGES)’ for 12 years.
He began making the observations from CSIRO’s Murchison Radio-astronomy Observatory (MRO) nine years ago, after seeking the best place on the planet for this work. He recently discovered an incredibly faint radio signal, coming from 13.6 billion years back in the universe’s history, and published the report of his discovery in Nature on March 1.
“Finding this miniscule signal has opened a new window on the early universe,” he said.
Antony Schinckel, CSIRO’s Head of Square Kilometre Array (SKA), who set up the MRO obervatory site, was less modest about the achievement.
“Finding this signal is an absolute triumph, a triumph made possible by the extreme attention to detail by Judd’s team, combined with the exceptional radio quietness of the CSIRO site,” he said.
“This is one of the most technically challenging radio astronomy experiments ever attempted. The lead authors include two of the best radio astronomy experimentalists in the world and they have gone to great lengths to design and calibrate their equipment in order to have convincing evidence for a real signal.”
The signal detected by Dr. Bowman and his team with the EDGES spectrometer fell in the region of the spectrum used by FM radio stations, meaning it was impossible to detect from most Earth-based sites.
The MRO observatory is located in a naturally extremely ‘radio-quiet’ location. This characteristic is additionally protected by a legislated ‘radio quiet’ zone up to 260 kilometres across, intended to prevent human-made activities that generate interfering radio signals to a minimum.
CSIRO developed the MRO observatory for its Australian Square Kilometre Array Pathfinder (ASKAP) telescope and also hosts a low-frequency telescope, the Murchison Widefield Array , developed by an international collaboration which is led by Curtin University.
These telescopes also take advantage of the radio-quiet nature of the site and are important precursors to the Square Kilometre Array itself. It is now the Australian site for the low-frequency telescope of the future Square Kilometre Array, SKA1 Low.