An international team of astronomers have used ultra-sensitive radio images to reveal thousands of star-forming galaxies in the early universe.
he scientists compiled the images using the International Low Frequency Array (LOFAR) telescope, a trans-European network of radio antennas.
It works by combining the signals from more than 70,000 antenna, located in stations across the Netherlands and in partner European countries including the UK.
Star formation is usually enshrouded in dust, which obscures our view when we look with optical telescopes, but radio waves penetrate the dustIsabella Prandoni, team member
By observing the same regions of sky repeatedly and combining the data to make a single very-long exposure image, the team detected the faint radio glow of stars exploding as supernovae, in tens of thousands of galaxies out to the most distant parts of the universe.
To produce the images, more than four petabytes of raw data – equivalent to about a million DVDs – were taken and processed.
Philip Best from the University of Edinburgh, who led the deep survey, said: “When we look at the sky with a radio telescope, the brightest objects we see are produced by massive black holes at the centre of galaxies.
“However, our images are so deep that most of the objects in it are galaxies like our own Milky Way, which emit faint radio waves that trace their ongoing star-formation.
“The combination of the high sensitivity of LOFAR and the wide area of sky covered by our survey – about 300 times the size of the full moon – has enabled us to detect tens of thousands of galaxies like the Milky Way, far out into the distant universe.
“The light from these galaxies has been travelling for billions of years to reach the Earth – this means that we see the galaxies as they were billions of years ago, back when they were forming most of their stars.”
Team member Isabella Prandoni, from the Italian National Institute for Astrophysics in Bologna, added: “Star formation is usually enshrouded in dust, which obscures our view when we look with optical telescopes. But radio waves penetrate the dust, so with LOFAR we obtain a complete picture of their star-formation.”
LOFAR is operated by ASTRON, the Netherlands Institute for Radio Astronomy.
The UK is a partner country in the project, alongside Ireland, France, Germany, Italy, Latvia, the Netherlands, Poland and Sweden.