A team of Australian scientists have discovered a group of galaxies thought to have existed only in the distant past.
The discovery reported in the journal Nature could improve sciences understanding of how galaxies and stars form.
It's also a feather in the cap of the paper's lead author Andy Green from Melbourne's Swinburne University, who is one of a handful of PhD students to have had their work appear on the cover of Nature.
Green says these galaxies are strange, lumpy and ancient looking.
"Similar primordial galaxies have been seen in Hubble Deep Field images looking back 13 billion years through space-time to when the universe was very young," he says. "We didn't think these sort of galaxies still existed, certainly not just a billion light years away."
Green says these galaxies look like disks, reminiscent of Andromeda or our own galaxy, the Milky Way.
"But they're physically turbulent places and are forming lots of stars, which is how they were discovered in the first place."
High stellar formation rates
Green and his team came across the galaxies whie looking for spectroscopic signatures for high star forming areas.
"We were comparing extreme galaxies today with the ancient Universe using the Sloan Digital Sky Survey, a kind of census of modern galaxies," he says.
"Such galaxies were thought to exist only in the distant past, when the Universe was very young".
Green says astronomers had previously thought extremely fast star formation took place in ancient galaxies fuelled by cold streams of gas continually falling in from outside the galaxy.
"It's a mechanism that only existed in the early Universe because much of this gas was thought to have been used up by now. But finding the same kind of galaxies in today's Universe means this mechanism can't be the only way rapid star formation is fuelled," he says.
"Instead it seems that when young stars form, they create turbulence in their surrounding gas."
"The more stars form in a galaxy, the more turbulence it has. And turbulence affects how fast stars form, so we're seeing stars regulating their own formation."
According to Green the discovery has raised some big questions.
"Where is the gas that makes these stars coming from? We don't think it's in reservoirs above the galactic disc. It might be coming from supernovae because there is a lot of supernova activity taking place in these galaxies," he says.
To get these answers, Green needs really big telescopes, and so plans to use the 10-metre Keck telescope in Hawaii to obtainan even closer look at these rare galaxies.
"We need a bigger telescope, [such as] the Giant Magellan Telescope to understand what's going on, but, until it's built, Keck is the best tool available," he says.