Dim galaxies shed light on dark matter
Our strange universe may be more bizarre than we thought.
‘We are on the verge of finding out what dark matter is’, Professor Carlos Frenk told the British Science Festival in Bradford. Frenk, director of Durham University’s Institute for Computational Cosmology, predicts that within the next few months, ‘Either dark matter will be discovered, or our model of the universe is not quite right.’
The ‘Lambda-cold dark matter theory’, (LCDM) currently predicts the behaviour of the cosmos. Visible material such as stars, planets and people makes up only 4 per cent of all matter, the rest being 21 per cent dark matter and 75 per cent dark energy, formed when the universe was a millionth of a second old.
Dark matter provides the gravity that structures the universe. Galaxies are born when clumps of dark matter attract ordinary gases that cool, coalesce and fragment, forming stars. The LCDM model predicts that galaxies have around ten times as much dark matter as visible material. The amount and position of the dark matter is predicted by modelling the gravity needed to power the orbits of these stars.
Frenk is studying the halo of small, dark galaxies at the edges of the Milky Way. These dwarf galaxies have surprisingly few stars. Frenk noticed something odd about these galaxies; ‘They just don’t have the structure which the theory predicts.’
He suggests two possibilities. ‘Either the birth of the dwarf galaxies was violent and damaged their dark matter haloes, or dark matter is not what we think it is.’
The Large Hadron Collider (LHC) at Cern in Switzerland has been designed to make ‘cold’ dark matter; these particles contain more than 100 protons. Frenk suggests that dark matter particles may be ‘warm’, a million times smaller. ’We can’t say what the LHC will find. If dark matter is warm, the particles they’re looking for won’t exist.’
‘If warm dark matter exists, we need new kinds of experiments to find it’, said Frenk. Now having to rethink his last 35 years as a cosmologist, his good humour leaves us in no doubt that the truth is out there.
‘We are on the verge of finding out what dark matter is’, Professor Carlos Frenk told the British Science Festival in Bradford. Frenk, director of Durham University’s Institute for Computational Cosmology, predicts that within the next few months, ‘Either dark matter will be discovered, or our model of the universe is not quite right.’
The ‘Lambda-cold dark matter theory’, (LCDM) currently predicts the behaviour of the cosmos. Visible material such as stars, planets and people makes up only 4 per cent of all matter, the rest being 21 per cent dark matter and 75 per cent dark energy, formed when the universe was a millionth of a second old.
Dark matter provides the gravity that structures the universe. Galaxies are born when clumps of dark matter attract ordinary gases that cool, coalesce and fragment, forming stars. The LCDM model predicts that galaxies have around ten times as much dark matter as visible material. The amount and position of the dark matter is predicted by modelling the gravity needed to power the orbits of these stars.
Frenk is studying the halo of small, dark galaxies at the edges of the Milky Way. These dwarf galaxies have surprisingly few stars. Frenk noticed something odd about these galaxies; ‘They just don’t have the structure which the theory predicts.’
He suggests two possibilities. ‘Either the birth of the dwarf galaxies was violent and damaged their dark matter haloes, or dark matter is not what we think it is.’
The Large Hadron Collider (LHC) at Cern in Switzerland has been designed to make ‘cold’ dark matter; these particles contain more than 100 protons. Frenk suggests that dark matter particles may be ‘warm’, a million times smaller. ’We can’t say what the LHC will find. If dark matter is warm, the particles they’re looking for won’t exist.’
‘If warm dark matter exists, we need new kinds of experiments to find it’, said Frenk. Now having to rethink his last 35 years as a cosmologist, his good humour leaves us in no doubt that the truth is out there.
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