r1034414 11862143 Supermassive Black Holes to Blame for Missing Hydrogen

The mystery of why hydrogen (the main ingredient of starts) is undetectable in the most distant regions of the universe may have been solved by Australian physicists. It looks like supermassive black holes lurking in the heart of distant galaxies could be to blame for the 'missing' hydrogen in the early universe.

The mystery of why hydrogen (the main ingredient of starts) is undetectable in the most distant regions of the universe may have been solved by Australian physicists. It looks like supermassive black holes lurking in the heart of distant galaxies could be to blame for the 'missing' hydrogen in the early universe.

According to findings published in the Astrophysical Journal, the discovery by Dr Stephen Curran of the University of Sydney and Dr Matthew Whiting of the CSIRO (Australia's Commonwealth Scientific and Industrial Research Organisation), explains why there doesn't appear to be enough hydrogen in the ancient universe to make all the stars we see today.
 
Curran and Whiting were studying radio signals caused by monster black holes feeding in some of the earliest galaxies, 11 billion light years away.
 
"These are some of the oldest objects in the universe," says Curran.
 
Stars form from clouds of cold hydrogen at temperatures of just a few degrees above absolute zero (-273°C), collapsing through their own gravity.
 
"If you've got a galaxy then you've got hydrogen," says Curran.
 
"By studying these hydrogen signatures, we can determine the size and rotation of galaxies."
 
But some of the galaxies Curran and Whiting looked at appeared to contain less hydrogen than expected.
 
"We looked at ten ancient galaxies and were surprised to find no signs of hydrogen in any," says Curran.
 
"There should have been more cold hydrogen gas in these ancient distant galaxies than there is today."
 
black hole Supermassive Black Holes to Blame for Missing Hydrogen
Artist's impression of a supermassive black hole. Source: NASA
 
As Curran and Whiting looked at other galaxy surveys, they found a critical level beyond which cold hydrogen could not be detected. It was found that in galaxies of certain luminosity, extreme levels of UV radiation given off by the supermassive black hole at its cores, generate enough energy to ionise all the hydrogen gas. This ionised hydrogen can't be detected by radio telescopes.
 
Of this, Curran said "We didn't know all the gas in the galaxy was being ionised. We thought it was just around the black hole's accretion disk."
 
"But it's the lot; ripping all the hydrogen into protons and electrons, preventing us from detecting it."
 
According to Curran, the Square Kilometre Array (SKA) radio telescope to be built in Australia, New Zealand and South Africa will provide a boost for their research.
 
"Not even the SKA can detect the hot ionised hydrogen in these active galaxies," says Curran.
 
"But it will let us look for other galaxies in the early universe which do have the cold hydrogen gas we're seeking."
 
Source: University of Sydney