"Long before it's in the papers"
September 05, 2009

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Oldest known black hole reported found

Sept. 3, 2009
Courtesy University of Hawaii
and World Science staff

As­tro­no­mers have found a gi­ant gal­axy sur­round­ing what they de­scribe as the old­est and most dis­tant black hole known. 

The gal­axy is as large as the Milky Way gal­axy and har­bors a “su­per­mas­sive,” or giant, black hole es­ti­mat­ed to weigh the equiv­a­lent of at least a bil­lion Suns. 

A black hole is an ob­ject so com­pact that its gra­vity drags in any­thing that pass­es too close by, in­clud­ing light rays. Some black holes are formed from burned-out stars, but others are too large to be ex­plained in this way and their ori­gin is some­what mys­ter­ious. 

The newfound black hole and galaxy are meas­ured as lying 12.8 bil­lion light years from Earth. Since a light-year is the dis­tance light trav­els in a year, that would mean that from Earth we see the gal­axy as it was that many bil­lion years ago.

It’s “sur­pris­ing that such a gi­ant gal­axy ex­isted when the Un­iverse was only one six­teenth of its pre­s­ent age, and that it hosted a black hole one bil­lion times more mas­sive than the Sun. The gal­axy and black hole must have formed very rap­idly in the early un­iverse,” said Un­ivers­ity of Ha­waii as­tron­o­mer To­mot­sugu Goto, one of the re­search­ers.

The find­ing is con­sid­ered im­por­tant in un­lock­ing the se­cret of how ga­lax­ies evolved to­geth­er with the super­mas­sive black holes that most of them con­tain at their cores.

Un­til now, stu­dy­ing black-hole-containing host ga­lax­ies in the dis­tant un­iverse has been ex­tremely dif­fi­cult be­cause the blind­ing bright light from near the black hole makes it harder to see the al­ready faint light from the host gal­axy.

Un­like smaller black holes, which form when a large star dies, the or­i­gin of super­mas­sive black holes re­mains an un­solved prob­lem. A cur­rently pop­u­lar mod­el re­quires sev­eral mid-sized black holes to merge to form the gi­ant black hole. 

The newfound gal­axy pro­vides a res­er­voir of such in­ter­me­diate black holes, ac­cord­ing to Goto and col­leagues. Af­ter form­ing, super­mas­sive black holes of­ten con­tin­ue to grow be­cause their gra­vity draws in mat­ter from sur­round­ing ob­jects. The en­er­gy re­leased in this pro­cess ac­counts for the bright light that these black holes pro­duce.

To see the super­mas­sive black hole, the team of sci­en­tists used new cam­era equip­ment in­stalled in the Sub­aru tel­e­scope on Mauna Kea, Ha­waii, and de­vel­oped by Satoshi Miyazaki of the Na­tional As­tron­o­my Ob­serv­a­to­ry of Ja­pan and col­leagues.

“We have wit­nessed a super­mas­sive black hole and its host gal­axy form­ing to­geth­er. This discovery has opened a new win­dow for in­ves­ti­gat­ing gal­ax­y-black hole co-evolution at the dawn of the un­iverse,” said You­suke Ut­sumi, al­so of the Na­tional As­tron­o­my Ob­serv­a­to­ry.

The re­search is to be pub­lished in the on­line ver­sion of the jour­nal Monthly No­tices of the Roy­al As­tro­nom­i­cal So­ci­e­ty this month.

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Astronomers have found a giant galaxy surrounding what they describe as the oldest and most distant black hole ever found. The galaxy is as large as the Milky Way galaxy and harbors a “supermassive” black hole estimated to weigh the equivalent of at least a billion Suns. The whole complex is measured as 12.8 billion light years from Earth. Since a light-year is the distance light travels in a year, that would mean that from Earth we see the galaxy as it was that many billion years ago. It’s “surprising that such a giant galaxy existed when the Universe was only one sixteenth of its present age, and that it hosted a black hole one billion times more massive than the Sun. The galaxy and black hole must have formed very rapidly in the early universe,” said University of Hawaii astronomer Tomotsugu Goto, one of the researchers. The finding is considered important in unlocking the secret of how galaxies evolved together with the supermassive black holes that most of them contain at their cores. Until now, studying the host galaxies in the distant universe has been extremely difficult because the blinding bright light from the vicinity of the black hole makes it more difficult to see the already faint light from the host galaxy. Unlike smaller black holes, which form when a large star dies, the origin of supermassive black holes remains an unsolved problem. A currently popular model requires several mid-sized black holes to merge to form the giant black hole. The host galaxy discovered in this work provides a reservoir of such intermediate black holes, according to Goto and colleagues. After forming, supermassive black holes often continue to grow because their gravity draws in matter from surrounding objects. The energy released in this process accounts for the bright light that these black holes produce. To see the supermassive black hole, the team of scientists used new camera equipment installed in the Subaru telescope on Mauna Kea, Hawaii, and developed by Satoshi Miyazaki of the National Astronomy Observatory of Japan and colleagues. “We have witnessed a supermassive black hole and its host galaxy forming together. This discovery has opened a new window for investigating galaxy-black hole co-evolution at the dawn of the universe,” said Yousuke Utsumi, also of the National Astronomy Observatory. This research is to be published in the online version of the journal Monthly Notices of the Royal Astronomical Society this month.