Dark matter 'highway' funnels gas into galactic pileup - space - 04 May 2009 - New Scientist

Description

The first tantalising signs of gas within a filament of dark matter have been glimpsed at the site of a cataclysmic collision between galaxy clusters. If future observations confirm the preliminary detection, it would provide an important test of computer simulations that show how large-scale cosmic structures form.

The simulations suggest that matter is distributed in a cosmic web, with material flowing along filamentary structures and pooling where the filaments intersect. Dark matter is thought to act as the scaffolding for this web, and researchers say as much as 40% of all dark matter in the universe may lie in the filaments.

But although observations have found that galaxies and galaxy clusters do indeed lie in filaments, so far no gas or dark matter have been confirmed in the highway-like structures.

"It's only logical that the gas and the dark matter trace the same structure, but quantitatively, we do not know whether the simulations and the observations match," says Harald Ebeling of the University of Hawaii.

Observing the gas in a filament could help gauge how much dark matter lies in the filament and thereby test theoretical models, he says, but "the gas in a filament has never been unambiguously detected".

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