Chandra image reveals black hole treasure trove

NASA said its Chandra X-ray Observatory has obtained an image that gives astronomers the best look yet at the growth of black holes over billions of years beginning soon after the Big Bang.

This is the deepest X-ray image ever obtained, collected with about eleven and a half weeks of Chandra observing time, the US space agency said in a statement.

The image comes from what is known as the Chandra Deep Field-South. The central region of the image contains the highest concentration of supermassive black holes ever seen.

"With this one amazing picture, we can explore the earliest days of black holes in the universe and see how they change over billions of years," said Pennsylvania State University's Niel Brandt, who led a team of astronomers studying the deep image.

About 70 per cent of the objects in the new image are supermassive black holes, which may range in mass from about 100,000 to 10 billion times the mass of the Sun.

Gas falling towards these black holes becomes much hotter as it approaches the event horizon, or point of no return, producing bright X-ray emission.

"It can be very difficult to detect black holes in the early Universe because they are so far away and they only produce radiation if they're actively pulling in matter," team member Bin Luo of Nanjing University in China noted.

"But by staring long enough with Chandra, we can find and study large numbers of growing black holes, some of which appear not long after the Big Bang," Luo added.

The new ultra-deep X-ray image allows scientists to explore ideas about how supermassive black holes grew about one to two billion years after the Big Bang.

Using these data, the researchers showed that these black holes in the early universe grow mostly in bursts, rather than via the slow accumulation of matter.

The scientists also found hints that the seeds for supermassive black holes may be "heavy" with masses about 10,000 to 100,000 times that of the Sun, rather than light seeds with about 100 times the Sun's mass.

This addresses an important mystery in astrophysics about how these objects can grow so quickly to reach masses of about a billion times the Sun in the early universe.

For the study, the team combined the Chandra X-ray data with very deep Hubble Space Telescope data over the same patch of sky.

These results were presented at the 229th meeting of the American Astronomical Society meeting in Grapevine, Texas.

--IANS

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