new_black_hole_000321As if donning a pair of red-and-blue glasses to watch a 3-D image pop out from a flat piece of paper, astronomers from England and France recently used NASAs Chandra X-ray Observatory to uncover a rare type of black hole hiding in a distant region of the universe.
Invisible to optical (visible-light) telescopes, a rare black hole known as a Type-2 quasar recently popped into view when some of its energy traveled some 6 billion light-years and hit the
Chandra X-ray Observatory, currently in orbit around Earth. The find marks the first time astronomers have proof of the existence of a Type-2 quasar.The Chandra X-ray Observatory is proving to be a powerful new tool for astronomers studying quasars and black holes in deep space. "Chandra is the first telescope that can make sensitive measurements of [high-energy] X-rays," said Andrew Fabian, a researcher at the
Institute of Astronomy in Cambridge, England. 
"When astronomers do an audit of the total energy output in the universe, they'll have to take all these hidden quasars into their calculation -- or they'll get a very wrong answer."
Chandra's ability to detect high-energy X-rays (as opposed to lower-energy radiation) allowed Fabian and his colleagues to observe the first unambiguous signs of a Type-2 quasar. These quasars have eluded scientists until now because each is obscured by a dust blanket, which is impenetrable by lower energy waves such as visible light.
"From the outside, all you see is a pretty normal galaxy no quasar," said Ian Smail, an astrophysicist at the University of Durham. "However, the most energetic X-ray photons can escape from the quasars dust blanket. Therefore, if you look in the X-ray band, youll see the hidden quasar shining through."
Quasar black hole connection
Scientists suspect that all quasars -- sources of powerful energy -- are black holes surrounded with a visible disc of hot gas. Quasars are believed to get their energy from matter when it falls into a black hole, which can be as massive as several billion of our suns. "A black hole alone is not a quasar, but a black hole with matter falling into it is one," explained Fabian. "Under current ideas, the presence of a quasar implies the existence of a black hole at its center.
Many experts believe that the number of quasars and therefore black holes existing in the universe is much greater than the number estimated from observations thus far. Now, with the discovery of Type-2 quasars, scientists have the evidence they need to confirm their suspicions.
"This discovery tells us that there is a significant class of obscured quasars out there," Fabian said.
The left panel shows the Chandra X-ray Observatory image of a powerful point-like source of X-rays. The Hubble Space Telescope image (right panel) shows the spiral galaxy with which the X-ray source is associated.
The universes energy sources
The other important lesson astronomers are gleaning from this discovery is that black holes may be more numerous than previously thought -- a possibility that is altering scientists understanding of the universes energy depots.
Understanding Type-2 quasars and their respective black holes will also have major implications for piecing together the puzzle of galactic evolution.
"Many more quasars (and their supermassive black hole power sources) may be hidden in otherwise innocuous galaxies," Smail said. "When astronomers come to do an audit of the total energy output in the universe, they have to take all these hidden quasars into their calculation -- or theyll get a very wrong answer."
"This can change our perspective on what the main sources of power in the universe are," explained Fabian. "Quasars may go from being a rarity of little overall consequence to being more common and of wider import."
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