Scientists say black holes are monstrously bigger than we thought

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Jun 26, 2015

A while back, we brought you news of a supermassive black hole that was 17 billion times more massive than our sun, making it among the biggest black holes ever found. We didn't think they could get much bigger than that, but new research suggests they can, and there may be more of these monsters than we ever thought.

"Ultramassive black holes -- that is, black holes with masses exceeding 10 billion solar masses -- are probably not rare; several and even dozens of these colossal black holes may exist," said Julie Hlavacek-Larrondo, an astrophysicist at Stanford University who served as lead author of a new study on black holes.

Using data from the NASA Chandra X-ray Observatory, along with other sources, Hlavacek-Larrondo and her team analyzed 18 of the brightest galaxy clusters (which are believed to contain the biggest black holes) we can see and found that at least 10 of the black holes at the centers of these galaxies are 10-40 billion times the mass of our sun. That's quite a few ultramassive black holes that we once thought were far less massive. So if these are actually that much bigger, just how big can these things get?

"Some of our black hole mass predictions are just lower limits, so they could be higher," Hlavacek-Larrondo said. "Just how big do I think they can get? I would bet that a least one 100-billion-solar-mass black hole exists among our objects, which really is ultra-big."

That's an absolutely whopping piece of astronomical news, but if the black holes really are this big, and were the whole time we were looking at them, how did we miss this?

Well, often the way we estimate the size of black holes is by simply observing how nearby objects (stars and the like) seem to be reacting to them, but by using Chandra to look at X-ray activity around the black holes, the researchers were able to get a better estimate. Basically, black holes generate X-rays when they consume gases in the surrounding area, and the Chandra Observatory can measure that X-ray output. By comparing the Chandra data with known relationships between the size of a black hole and the X-rays it gives off, Hlavacek-Larrondo and her team were able to get new estimates of the size of these black holes.

"These results may mean we don't really understand how the very biggest black holes coexist with their host galaxies," said study co-author Andrew Fabian of England's Cambridge University. "It looks like the behavior of these huge black holes has to differ from that of their less massive cousins in an important way."

The findings could change the way we think about how black holes affect the galaxies they reside in, as well as what we know about black hole growth and evolution. Researchers are hoping that the James Webb Space Telescope, a Hubble successor due to launch in 2018, will shed new light on these findings. For now, let's just ponder the implications of black holes that are up to 10 times bigger than we thought they were.

(Via Huffington Post)