Dark-matter 'deficient' galaxy found
The finding has prompted scientists to reconsider how galaxies form
Astronomers are scratching their heads after a research team discovered a galaxy that seems to be devoid of any dark matter. Located millions of light years away, galaxy NGC-1052-DF2 appears to consist entirely of ordinary matter which, if proven, goes against the theory that dark matter should be present wherever ordinary matter exists.
Most astronomers subscribe to the notion that roughly 27 per cent of the universe is made up of dark matter, while ordinary matter – the stuff we can see – accounts for five per cent. The discovery – or nondiscovery, if you like – that there is 400-times less dark matter than expected given the size of the galaxy raises the possibility it is a separate material elsewhere in the universe. It defies the idea that the interaction of stars and galaxies within dark matter produced the galaxies we see today.
“We thought that every galaxy had dark matter and that dark matter is how a galaxy begins,” explains Pieter van Dokkum, Yale’s Sol Goldman Family Professor of Astronomy. “So finding a galaxy without it is unexpected. It challenges the standard ideas of how we think galaxies work, and it shows that dark matter is real. It has its own separate existence apart from other components of galaxies.
This result also suggests that there may be more than one way to form a galaxy.”
The galaxy NGC 1052-DF2 is missing
most, if not all, of its dark matter