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Supermassive blackholes are giants from birth

At the heart of virtually every galaxy, including the Milky Way, is a supermassive blackhole that’s anywhere from hundreds of thousands to billions of times more massive than the sun. How these cosmic bodies start off is still a subject of debate. Do they start off small and steadily grow by merging with other black holes or are they really big since inception? A new study seems to incline towards the latter.

This is a rendering of what a supermassive black hole seed should look like. Two candidate seeds as captured by Chandra (left) and Hubble (right) are featured in the inset boxes. Credit: NASA/CXC/M.Weiss

This is a rendering of what a supermassive black hole seed should look like. Two candidate seeds as captured by Chandra (left) and Hubble (right) are featured in the inset boxes. Credit: NASA/CXC/M.Weiss

Andrea Ferrara, of Scuola Normale Superiore in Pisa, Italy and colleagues scoured the night’s sky for supermassive blackhole “seeds” using data from the Hubble, Chandra X-ray and Spitzer infrared space telescopes.

A simple black hole that’s, say, a couple hundred to a couple thousand times more massive than the sun typically form when a massive star collapses upon itself.  A supermassive blackhole might start as a lonely black hole that grows to gargantuan proportions by ‘eating’ other black holes. Alternatively, it can grow by pulling gas from its surroundings.



Using computer models, the team led by Ferrara identified two probable supermassive black hole seeds that matched the predicted red-shift. Each contains about 100,000 solar masses and formed 1 billion years after the Big Bang. Their analysis suggests that supermassive black holes “form directly from the collapse of a giant gas cloud, skipping any intermediate steps”. This is at least true for those ancient supermassive black holes which formed more than 12 billion years ago.

“There is a lot of controversy over which path these black holes take,”said Ferrara. “Our work suggests we are narrowing in on an answer, where the black holes start big and grow at the normal rate, rather than starting small and growing at a very fast rate.”

The findings are preliminary, so expect more work to investigate whether these objects are indeed black hole seeds. Regarding their origins, any definite conclusion will require a lot more than just two objects to make.


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