NASA: Supermassive Black Holes at Heart of Ancient Galaxies

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Occasionally supermassive and always super-ominous, light-devouring black holes may be the most spectacular byproduct of our Newtonian universe, and now we know a little more about how long they’ve been out there and what they’re up to, thanks to NASA’s Chandra X-ray Observatory.

Astronomers pointed Chandra at a strip of sky for over six weeks, searching for black holes among 200 galaxies distant enough to represent the universe when it was between 800 million and 950 million years old.

What they found: throngs of hyperactive black holes.

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“Until now, we had no idea what the black holes in these early galaxies were doing, or if they even existed,” said Chandra/Einstein fellow Ezequiel Treister of the University of Hawaii, lead author of the study, which appears in the June 16th issue of Nature. “Now we know they are there, and they are growing like gangbusters.”

Black holes can form when exceptionally dense stars collapse from their own gravity to form an object—the black hole, or gravitational singularity—whose density is infinite. You know how the rest of the story goes: nothing can escape the pull of a singularity, not even light. Supermassive black holes are basically the super-sized versions, thought to inhabit the center of large galaxies, including our own Milky Way.

Scientists had predicted black holes formed during the universe’s earliest days, but because of gas and dust absorbing all visible radiation save for “the highest-energy X-rays,” we lacked observational evidence—until now.

By combining “the deepest X-ray image ever taken” via Chandra with infrared images from the Hubble Space Telescope, NASA found that “between 30 and 100 percent” of the galaxies scanned harbor actively growing supermassive black holes. Extrapolate throughout the rest of the universe and you’re talking upwards of 30 million supermassive black holes populating the early universe. Black hole growth observed by the team was also “a hundred times higher” than prior estimates.

“It appears we’ve found a whole new population of baby black holes,” said study co-author and Einstein Fellow Kevin Schawinski of Yale University. “We think these babies will grow by a factor of about a hundred or a thousand, eventually becoming like the giant black holes we see today almost 13 billion years later.”

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Another surprising study takeaway: Black holes don’t just grow in tandem with recent galaxies, they’ve apparently been doing so from the very beginning.

“Most astronomers think in the present-day universe, black holes and galaxies are somehow symbiotic in how they grow,” said Priya Natarajan, another study co-author and a professor in the Departments of Astronomy and Physics at Yale University. “We have shown that this codependent relationship has existed from very early times.”

Of course the latest scientific answers conjure new mysteries. What we still don’t know: according to Treister, what causes the relationship, and why it happens so quickly.

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