Massive dark matter in ‘failed’ galaxies detected

Melbourne, July 20 (IANS) Certain “failed” galaxies in a cluster roughly 300 million light years from Earth could contain as much as 100 times more dark matter than visible matter, says an Australian study.

The galaxies appear to have stopped making new stars when they first fell into the cluster between seven and ten billion years ago and have been dead ever since, said lead researcher Cameron Yozin from the University of Western Australia.

The research used powerful computer simulations to study galaxies that have fallen into the Coma Cluster, one of the largest structures in the universe where thousands of galaxies are bound together by gravity.

“The galaxies could have fallen into the cluster as early as seven billion years ago, which, if our current theories of galaxies evolution are correct, suggests they must have lots of dark matter protecting the visible matter from being ripped apart by the cluster,” Yozin said.

The findings were reported in the journal Monthly Notices of the Royal Astronomical Society.

Dark matter cannot be seen directly but the mysterious substance is thought to make up about 84 percent of the matter in the universe.

Yozin said the galaxies he studied in the Coma Cluster are about the same size as our own Milky Way but contain only one percent of the stars.

“Galaxies originally form when large clouds of hydrogen gas collapse and are converted to stars – if you remove that gas, the galaxy cannot grow further.”

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