Monday, February 28, 2011

Dark matter theory challenged by gassy galaxies result

Gas-rich galaxy F549-1A controversial theory that challenges the existence of dark matter has been buoyed by studies of gas-rich galaxies.

Instead of invoking dark matter, the Modified Newtonian Dynamics theory says that the effects of gravity change in places where its pull is very low.

The new paper suggests that Mond better predicts the relationship between gassy galaxies' rotation speeds and masses.

However, critics maintain that dark matter theory is a better general description of the Universe we see.

The study, available online, will be published in Physical Review Letters.

The theory that first proposed dark matter was developed in large part to account for mass that, if everything else we think about gravity is correct, seemed to be missing in rotating galaxies.

Standard formulations of gravity have it that matter circling, for instance, spiral galaxies, should rotate more slowly with increasing distance from the centre of the galaxy - much as the outer planets in our Solar System orbit more slowly than their innermost counterparts.

But the matter in rotating galaxies seems consistently to rotate with roughly equal speed near their cores and at their edges.

In the standard dark matter theory, cosmologists proposed a massive yet invisible quantity of material in order to solve this "flat rotation curve" problem.

This dark matter is imagined to exist in a "halo" around galaxies, providing the extra gravitational pull necessary to speed up those outlying bodies. ...

via BBC News - Dark matter theory challenged by gassy galaxies result.

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