Universe’s biggest galaxies may have fed on dark matter to grow quick

April 7th, 2009 - 12:38 pm ICT by ANI  

London, April 7 (ANI): In a new research, scientists have determined that some of the biggest galaxies in the early universe seem to have grown quicker than thought possible and may have bulked up on streams of gas flowing along filaments of dark matter.

Monster galaxies have long been thought to take a long time to form, growing slowly by gobbling up smaller galaxies like a giant amoeba absorbing food.

According to a report in New Scientist, a new research performed using the Subaru telescope in Hawaii, has suggested that overeating in this way cannot explain why some of the brightest galaxies at the heart of five clusters dating from relatively soon after the big bang - more than 8 billion years ago - grew so large.

Models suggest that if they snacked only on other galaxies, those ancient leviathans should have been just a fifth as massive as the biggest galaxies in similar clusters today that have had longer to eat their smaller neighbours.

But instead the ancient galaxies appear to be roughly 90 per cent as massive as their present-day counterparts.

“It could be the tip of the iceberg. It might mean the simulations (of the early universe) need to be significantly altered,” said Chris Collins of Liverpool John Moores University in Birkenhead, UK.

“Either simulations of large galaxies gobbling up smaller ones have misjudged some physical principles, like star formation and the behaviour of gas, or the rapid growth was fed by a completely different diet,” said Collins.

There is a limit on how quickly galaxies can draw in gas needed to fuel star formation, since pulling it in too fast raises its temperature to create a shock-wave-like barrier that prevents more gas from entering.

However, simulations published earlier this year suggest early galaxies could feed more quickly if they were situated on filaments of dark matter that act like pipes, allowing gas to flow rapidly into a galaxy while staying cool.

These filaments may already have been spotted in mystery blobs of hydrogen recently found surrounding other galaxies, according to Collins.

Finding such features in the dust around these large galaxies could be additional evidence that dark matter may be responsible.

According to Kenneth Rines of Western Washington University in Bellingham, Washington, “Overall, the results are every intriguing. They show the history of these monster galaxies is more complex than we expected.” (ANI)

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