Thursday, February 26, 2015

Black hole much bigger than Sun found: Scientists - Times of India

LONDON: Astronomers have found the largest black hole till date — as big as 12 billion times bigger than the sun and 420 trillion times more luminous than our sun.

An international team of astronomers have found a huge and ancient black hole which was powering the brightest object early in the universe.


The black hole's mass is 12.8 billion light years away — the most luminous object ever seen in such ancient space.


It's also from just 900 million years after the big bang. The hole was found at the centre of a quasar that pumped out a million billion times the energy of our Sun.


Team member Dr Fuyan Bian from the Research School of Astronomy and Astrophysics at the Australian National University (ANU) said the discovery challenges theories of how black holes form and grow in the early universe.


The team said that the brightness and size are surprising in a black hole from so close to the dawn of time.


In a new study published in on Wednesday, researchers described "a cosmic light that defies convention. It was even detectable with a relatively small telescope, though researchers in China did have to ask for help from astronomers in Chile and the United States to get a higher-resolution look".


"Forming such a large black hole so quickly is hard to interpret with current theories," the team said.


A quasar is an extremely bright cloud of material in the process of being sucked into a black hole. As the material accelerates towards the black hole it heats up, emitting an extraordinary amount of light which actually pushes away material falling behind it.


This process, known as radiation pressure, is thought to limit the growth rate of black holes, Dr Bian said.


"However this black hole at the centre of the quasar gained enormous mass in a short period of time," Dr Bian said.


The team led by Xue-Bing Wu at Peking University, China, selected the quasar from the Sloan Digital Sky Survey of over 500 million objects in the northern skies, because of its distinctive red colour. They then followed up with three other telescopes to study the object in detail.


Dr Bian expects more surprising objects will be discovered during the Skymapper survey of the southern skies, currently being run by the ANU.


"Skymapper will find more of these exciting objects. Because they are so luminous we can see further back in time and can use them to explore the early universe," Dr Bian said.



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