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Although not the largest black hole ever found, J0100+2802 appears to confound current theories about the creation and evolution of black holes

Formed around 900 million years after the Big Bang—dating back to around six percent of the Universe’s current age—with a mass 12 billion times that of the Sun—six times greater than its largest-known contemporaries—astronomers have discovered the largest and most luminous black hole yet. Undermining modern scientific theories, its discovery challenges theories of the creation and evolution of black holes with questions remaining about how this black hole could have grown so huge in such a relatively brief period of time following the dawn of the Universe.

Supermassive black holes are believed to be lurking at the centre of most, if not all, large galaxies: the black hole at the heart of the Milky Way, for example, is thought to have a mass between four and five million times that of the Sun. Astronomers also suspect that quasars—the brightest objects in the Universe and intensely powerful galactic radiation sources—contain supermassive black holes that expel massive amounts of light as mass falls onto their accretion discs.

Astronomers have located 40 quasars that date back to when the Universe was less than 1 billion years old. However, a team of global scientists led by Xue-Bing Wu at Peking University have now reported the discovery of a supermassive black hole—at the centre of a quasar—12 billion times the mass of the Sun that dates back to when the Universe was only about 875 million years old. Until now, the most massive known black hole less than 1 billion years old was two billion solar masses.

Around 12.8 billion light-years from Earth, the black hole, known as SDSS J010013.02+280225.8 or J0100+2802 for short, is at the centre of a quasar that is not only the most massive quasar yet seen in the early Universe, but also the most luminous: about 429 trillion times brighter than the Sun and seven times brighter than the most distant quasar known.

Professor Xue-Bing Wu, who led the discovery and the study reported in the journal Nature, announced: “This quasar is very unique. We are so excited when we found that there is such a luminous and massive quasar only 0.9 billion years after the Big Bang.”

“Just like the brightest lighthouse in the distant Universe, its glowing light will help us to probe more about the early Universe,” Professor Wu added.

J0100+2802 was spotted, in 2013, using the Lijiang Telescope in Yunnan, China. Its quasar appeared as a bright, red, light source with a redshift—a measurement of the stretching of light to the red end of the spectrum by the expansion of the Universe—of 6.30. With a redshift higher than six, the yardstick used to define the early Universe boundary, the team performed further studies of the quasar’s spectrum to estimate the velocity of the infalling gas and J0100+2802’s massive solar mass.

When light from a quasar shines toward Earth, it passes through intergalactic gas that colours it. Analysis of how intergalactic gas influences the spectrum of light can enable scientists to deduce which elements make up the gas, providing insights into the star-formation processes that were at work shortly after the Big Bang. Scientists hope that the ultraluminous nature of this quasar will allow them to make unprecedented measurements of the temperature, ionisation state and metal content of the intergalactic medium at the epoch of reionisation: when gravity brought pieces of matter together and formed the first stars and galaxies.

However, astronomers still cannot explain how J0100+2802 could have formed so soon in the early Universe. To gain mass, black holes swallow the interstellar matter around them and merge with other large black holes. How such an enormous black hole formed in such a short period of time following the creation of the first stars and galaxies remains debated.

“This [discovery] is quite surprising because it presents serious challenges to theories of black hole growth in the early universe,” said Professor Wu.

Co-author Dr Yuri Beletsky, from the Carnegie Institution in Washington DC, added: “This quasar is a unique laboratory to study the way that a quasar’s black hole and host galaxy co-evolve.”

“Our findings indicate that in the early Universe, quasar black holes probably grew faster than their host galaxies, although more research is needed to confirm this idea.”

— Rebecca Davies, Editor (Science)

Image Courtesy: NASA Goddard Space Flight Centre (https://www.flickr.com/photos/gsfc/15084150039), Licensed under the Creative Commons Attribution 2.0 Generic | Flickr

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