Unusual signals have led scientists to previously unseen galaxies – and there may be many, many more waiting to be found.
Scientists have long been trying to learn more about the history of the early universe by looking deep into space. Distant galaxies allow us to see how close the universe was to its beginning, effectively allowing astronomers to look back in time.
Astronomers have been doing this using a variety of different observations, through the Hubble Space Telescope and telescopes on Earth. More recently, those observations have been further facilitated by observations through the Atacama Large Millimeter/submillimeter Array, or ALMA, which allows them to see distant galaxies at submillimeter wavelengths.
They are specifically looking at a group of 40 target galaxies that researchers have been able to see early in the universe. And it was in that research — known as the Rebels, or Reionization-Era Bright Emission Line Survey — that they found more than expected.
Picking through the data, the researchers found unusual signs. They observed that the dust emitted strongly – but even with very sensitive instruments, no ultraviolet light was coming from the places.
They found that the signal was actually coming from two previously unknown galaxies that were close to the two targets scientists were looking at as part of REBELS’s work.
They were missed because they were almost entirely covered by dust, the scientists said, adding that one of the most distant galaxies is covered in dust. And they were found almost by accident.
What’s more, there may be many more of those galaxies waiting to be discovered. “It is possible that we are missing one in every five galaxies by now in the early universe,” said Yoshinobu Fudamoto, who led the research.
A study detailing the findings, published in ‘Normal, dust-obscured galaxies in the era of reionization’ Nature.
Credit: www.independent.co.uk /