Rare discovery is 10 billion times larger than sun
(From space.com):
From:
http://www.msnbc.msn.com/id/5318411/By Tariq Malik
Updated: 4:19 p.m. ET June 28, 2004A team of astronomers have found a colossal black hole so ancient, they're not sure how it had enough time to grow to its current size, about 10 billion times the mass of the sun.
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Sitting at the heart of a distant galaxy, the black hole appears to be about 12.7 billion years old, which means it formed just one billion years after the universe began and is one of the oldest supermassive black holes ever known.
The black hole, researchers said, is big enough to hold 1,000 of our own Solar Systems and weighs about as much as all the stars in the Milky Way.
"The universe was awfully young at the time this was formed," said astronomer Roger Romani, a Stanford University associate professor whose team found the object. "It's a bit of a challenge to understand how this black hole got enough mass to reach its size."
Romani told SPACE.com that the black hole is unique because it dates back to just after a period researchers call the 'Dark Ages,' a time when the universe cooled down after the initial Big Bang 13.7 billion years ago. That cooling period lasted about one billion years, when the first black holes, stars and galaxies began to appear, he added. The research appeared June 10 on the online version of Astrophysical Journal Letters.
Invisible to the naked eye, black holes can only be detected by the radiation they spew and their gravitational influence on their stellar neighbors. Astronomers generally agree that black holes come in at least two types, stellar and supermassive. Stellar black holes form from collapsed, massive stars a few times the mass of the sun, while their supermassive counterparts can reach billions of solar masses.
A supermassive black hole a few million times the mass of the sun is thought to sit at the center of our own Milky Way galaxy, and some of the largest supermassives seen date have reached up to two billion solar masses, researchers said.
Weighing a black hole heavyweight
Determining a precise mass for the black hole found by Romani's team, dubbed Q0906+6930, is a bit tricky though since it's so far away.
"Very massive black holes like this are so rare, that one should really be a little suspicious at first," Romani said.
The black hole, called a blazar because it spews jets of radiation in roughly the direction of Earth, sits at the center of a galaxy about 12.7 billion light-years away in the constellation Ursa Major. One light-year is the distance light travels in one year, is about six trillion miles (10 trillion kilometers).
Because the blazar is so distant, there are no nearby neighbors to scan for potential gravitational effects, and much of its radiation is absorbed by gas and dust lying between it and the Earth, Romani said.
"It really is too far away to do a direct orbital measurement to help determine its mass," Romani said, adding that he and his colleagues had to estimate the mass based on a quantitative method that includes measuring particle velocity and the Doppler shift of its infrared emission lines. "The best thing to do is study it in a broader region of the spectrum, to get more emission lines."
Next year, researchers plan to scan the blazar's X-ray emissions with the Very Large Baseline Array and take other measurements to pin down a more accurate mass for the object, and eventual gamma-ray studies could refine that number even more.
A good catch
The blazar found by Romani and his colleagues is one of about 200 they have catalogued to date in preparation for the Gamma Ray Large Area Space Telescope (GLAST) planned for launch in 2007. The researchers are using a collection of optical, gamma-ray and radio observations for their study.
Since that mission is aimed at studying high-energy radiation sources like pulsars and spinning neutrons stars and others, researchers wanted to be able to filter out blazar interference before GLAST begins operations. But the discovery of blazar Q0906+6930, has yielded a few added scientific benefits.
"It suggests the blazar phenomena turned on much earlier than we thought," Romani said of the black hole. "So it really pushes on the formation scenarios we have for black holes."
Close study of the blazar's jet could also give astronomers a good picture of all the matter lying between Earth and the massive black hole since it has to pass through such material to reach astronomers' telescopes.
"So that's a way of using this weird, anomalous object to help our understanding of the universe," Romani said, adding that he and his colleagues plan to continue their blazar hunt until GLAST begins. "But I would be very surprised if there were a large number of these objects."
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