An artist rendering of a black hole feasting on its surroundings. The central black hole is hidden from direct view by a thick layer of encircling gas and dust. (NASA/ESA)

Black holes — supermassive or otherwise — sound like the stuff of science fiction. They’re without question real, and scientists have now discovered five supermassive ones hidden previously from view by dust and gas. Other researchers found a black hole that grew faster and bigger than they expected it to, among the biggest ever discovered.

Contrary to popular belief, black holes aren’t empty; they’re so full, in fact, packed so densely, that even light isn’t able to escape. Hence its name. Scientists believe that almost every galaxy has at its center a black hole. A supermassive black hole is one that’s more than a million times as big as our sun — at a minimum.

Our Milky Way has a supermassive black hole at its core, 4 million times as large as the sun. (Not to worry, scientists say it’s dormant.) But using NASA’s and the in Hawaii, Benny Trakhtenbrot of ETH Zurich’s Institute for Astronomy and a team of researchers from around the world discovered one 7 billion with a B times as large as the sun. “It was slightly beyond 10 percent of the mass of the whole galaxy,” Trakhtenbrot told weather.com. “It’s a huge black hole in a very normal, typical galaxy in the universe.” Generally, a black hole measures about 1 percent the size of its host galaxy.

That supermassive black hole — which counters prevailing theories that these grow in parallel to their galaxies — is still expanding; the researchers wouldn’t have been able to see it otherwise. But its pace has slowed significantly, telling them that the black hole is likely nearing its final stages of development. Trakhtenbrot said there are likely other similar black holes we haven’t yet encountered.

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“This is but one system which managed to surprise us, but it’s still a single object,” he said. “We’re working hard to expand this to a larger sample of black holes … hoping to [get] a more complete picture of black holes in the early universe.” Research out of Durham University could help in that regard.

George Lansbury, of Durham, and colleagues aimed NASA’s Nuclear Spectroscopic Telescope Array at places they suspected supermassive black holes to exist, “candidates,” as they called them. High-energy X-rays confirmed that “rapidly feasted on surrounding material and emitted large amounts of radiation,” noted a news release.

“For the first time we have been able to clearly see these that are predicted to be there, but have previously been elusive,” Lansbury, the lead researcher, said in a statement. Despite confirming just five of these black holes, the scientist said he suspects many more exist. “When we extrapolate our results across the whole universe, then the predicted numbers are huge” — possibly millions, in fact.

It’s perplexing to think that something with the word “supermassive” in its name could stay concealed by covering so ephemeral and seemingly transparent as dust and gas. But until a few years ago, no telescope had the ability to detect high enough energy X-rays. Then along came the NuSTAR, which launched in 2012.

Whatever the means to their discovery, these black holes tell us there’s much more of the universe left to explore.

Trakhtenbrot and team published their research in Science. Lansbury’s research will run in The Astrophysical Journal.

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The ESO 3.6-meter telescope at La Silla observatory in Chile, during observations. (ESO/S. Brunier)