A galaxy five billion light years away has been discovered using a hi-tech telescope array located in the remote outback of Western Australia.
Thanks to radio emission that the newly-discovered galaxy, dubbed PKS B1740-517, is spewing, the Australian Square Kilometre Array Pathfinder telescope (ASKAP) managed to pick up the structure’s signal. It’s due ASKAP’s extremely unique radio quietness that a research team led by James Allison at the Commonwealth Scientific and Industrial Research Organisation (CSIRO) were able to break open a window to an unexplored time in the universe’s past.
The radio signal emitted by the newfound galaxy, which took five billion years to reach us, was also discovered to contain an ‘imprint’ of hydrogen gas – something that’s quite difficult to detect by a telescope located at a site that’s buzzing with background radio noise. Astronomers are able to find the signature of hydrogen gas by hunting for dips in the radio signals that sensitive telescopes can pick up. “At many observatories, this dip would have been hidden by background radio noise, but our site is so radio quiet it stood out clearly,” says Allison.
The cold hydrogen gas that Allison and his team detected is the raw material required for forming stars and is found to be plentiful in a good proportion of galaxies. The newly found signal may be small, but according to Allison, has some fairly big implications: “This catch shows we’re going to bag a big haul of galaxies,” he says.
The ability to be able to detect such a small wisp of cosmic radio waves, emitted before our Solar System was even born, illustrates that ASKAP – a new facility – is currently the only array to be able to locate galaxies that other telescopes can’t. “We’ll be able to detect hydrogen gas deeper in space and, thanks to ASKAP’s wide field of view, also over a much larger volume than we could before,” explains Elaine Sadler of the University of Sydney and the ARC Centre of Excellence for All-sky Astrophysics (CAASTRO). “We’ll be hunting for galaxies that are five to eight billion years old, a timespan that represents a fifth of the universe’s history.”
Some ten billion years ago, galaxies were making stars around ten times faster than today. Sadler hopes that by looking at galaxies that are five to eight billion years old, we can begin to understand why the rate dropped. “We want to learn how much hydrogen galaxies had in this period for forming stars,” she adds. “Until now we’ve had few tools for doing that.”