Universe’s ‘missing matter’ is finally found
Scientists clear up a mystery by locating the elusive third of ordinary matter created when the cosmos was born
Astrophysicists have finally pinned down the location of a huge amount of missing ordinary matter, going a long way to solving a mystery dating back some 20 years. Scientists at the University of Colorado Boulder say the missing matter is found in the space between galaxies. They made the discovery by observing a distant, ultra-bright black hole.
The study was inspired by a stark discrepancy between the amount of ordinary matter calculated to have been created during the Big Bang and the amount that could be seen with telescopes today. Up until the recent findings, only twothirds of ordinary matter, known as baryons, had ever been located, leaving a big question mark over the remaining third.
By pointing a series of satellites skywards, the scientists were able to monitor the radiation emanating from a distant quasar. First of all they used the Cosmic Origins Spectrograph on the Hubble Space Telescope to work out where the missing baryons may be located.
They then used the European Space Agency's X-ray Multi-Mirror Mission satellite for a closer inspection.
They found that the lost matter exists as thin, hot clouds of oxygen gas at temperatures of about a million degrees Celsius (about 1.8 million degrees Fahrenheit). It was just as Michael Shull, a co-author of the study at the university, had predicted in 2012. Back then they had reckoned on the missing 30 per cent being in a web-like pattern of space called the warm-hot intergalactic medium.
As expected, the news has been greeted with a lot of excitement. “We found the missing baryons,” says Shull. The findings will now need to be confirmed by monitoring more bright quasars. But the ability to record how radiation from a quasar passes through space and how it changes the light from that black hole is a stunning breakthrough.
It goes a long way to answering questions about how the universe began, but it also poses conundrums of its own. “How does [ordinary matter] get from the stars and the galaxies all the way out here into intergalactic space?” asks Charles Danforth, a research associate at the University of Colorado Boulder. “There's some ecology going on between the two regions and the details of that are poorly understood.”
The new study appears in Nature and it was led by Fabrizio Nicastro of the Italian Nazionale di Astrofisica – Osservatorio Astronomico di Roma and the Harvard-Smithsonian Center for Astrophysics. The baryons, however – which make up all of the physical objects in existence from black holes to the stars – are not to be confused with dark matter.
“We found the missing baryons”