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    Astronomers discover clues to when the stars first began to twinkle

    An artist’s depiction of the newly discovered supermassive black hole, the most distant black hole ever observed.
    Robin Dienel, Carnegie Institution for Science
    An artist’s depiction of the newly discovered supermassive black hole, the most distant black hole ever observed.

    Researchers say they have detected a mysterious supermassive black hole that technically should not exist — and, while studying it, have discovered when the stars first lit up the sky.

    The researchers have detected the most distant supermassive black hole ever observed. But based on the size of the Goliath and the age of the universe, it should not exist, said Robert Simcoe, a physics professor at MIT.

    “The universe was just not old enough to make a black hole that big,” Simcoe said in a statement from MIT. “It’s very puzzling.” Simcoe was a lead author of a paper on the discoveries, published Wednesday in the journal Nature. He was joined by another researcher from MIT and researchers from several other institutions.

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    The mass of the black hole is 800 million times that of the sun, the university said, and it sits in the center of a galactic object called a quasar. Quasars consist of a supermassive black hole and the swirling bits of matter it absorbs.

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    When the matter falls into the black hole, it heats up and allows the quasar to emit light, Simcoe said. That’s how astronomers detect black holes. And they measure their size by looking at the brightness of the quasar.

    The light from this quasar was emitted 690 million years after the Big Bang, relatively close to the beginning of everything. It took another 13 billion years to reach the earth, the researchers found.

    “Here we see this thing that’s very bright coming from very early in the universe,” Simcoe said.

    While the black hole itself remains a mystery, its existence provided the team with another discovery: information about when the stars first turned on, Simcoe said.

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    The black hole formed at a time the universe was changing from a neutral environment to an ionized environment, he said.

    “What transitions the universe from being neutral to ionized is starlight from the first galaxies,” he said.

    As more stars formed, they generated enough radiation to flip hydrogen from its neutral state to an ionized state.

    When the black hole formed more than 13 billion years ago, the universe was about half ionized and half neutral, Simcoe said. That indicated to researchers that the stars were just beginning to glow, he said.

    “In some sense, what we’ve done is determine with a high degree of accuracy when the first stars in the universe turned on,” he said.

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    Simcoe said he anticipated astronomers would be able to detect many more black holes of similar sizes and ages going forward, and he hoped they might one day be able to explain how the one researchers discovered grew so large in such a short amount of time.

    But for now, he’s happy to have answered one of the fundamental questions about the age of the universe: when the stars began to twinkle.

    “We think of them as being something that’s eternal, but really, there was a time when the universe was just dark matter,” he said.

    Alyssa Meyers can be reached at alyssa.meyers@globe.com. Follow her on Twitter @ameyers_.