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An international team of astronomers have unexpectedly found hundreds of expanding "supermassive" (1) black holes buried deep inside galaxies billions of light years from earth.
The astounding discovery is the first direct evidence that most - perhaps all - huge (2) galaxies in the far reaches of the universe generated cavernous black holes during their youth, when about 3.5 billion years old. Scientists generally agree that (3) the universe as we perceive it came into being about 14 billion years ago.
Astronomers have long assumed there were far more so-called "active" black holes than had been observed, but were unable to find any trace of them.
These supermassive entities are known as high-energy quasars, a form of black hole that is surrounded by a thick halo of gas and dust which shoot off X-rays as they are sucked into the void.
The X-rays, which can be detected as a general glow in space even when the quasars themselves cannot be seen, are what tipped off the scientists that they had stumbled across something extraordinary.
Two telescopes were needed to see the black holes. One is NASA's Spitzer space telescope, which picks up infrared light, and the other is the Chandra telescope, which relays X-ray data.
The newfound quasars will help answer fundamental questions about how massive galaxies evolve. Astronomers now know, for example, that most of these galaxies steadily generate stars and black holes simultaneously until the latter become too big and impede star formation. ■AFP
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