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Hot ionized gas is streaming out of the accretion disk of a supermassive black hole and slamming into its surroundings at a significant fraction of the speed of light. And this kind of ultra-fast outflow (UFO) might explain the nearly empty darkness that surrounds the center of many galaxies, astronomers now say.
These astronomers base their argument, published in the July issue of the journal Astronomy and Astrophysics, on a new observation of galaxy PG 1114+445 from the European Space Agency’s X-ray Multi-Mirror Mission (XMM-Newton) telescope. For the first time, the researchers were able to snap an image of UFOs pushing other material around at the heart of a galaxy.
Their observations showed that energy was being transferred from the UFO to other winds near the black hole, pushing that wind to incredible speeds. This is important, the researchers wrote, because it could explain a long-standing mystery about supermassive black holes: The bigger the supermassive black hole, the faster the inner stars in its host galaxy move. Gravity alone can’t explain this relationship, but if the larger black holes spew more intense outflows that shove out gas at higher speeds, they could also be sweeping away nearby stars and accelerating them to higher speeds.
(A figure from the paper shows how UFOs mix with surrounding matter to create entrained UFOs and shove things around in space)
To make this first-of-its-kind observation, the researchers imaged a UFO alongside two other types of outflows near the black hole: “warm absorbers,” which travel much more slowly and are less ionized, and rare “entrained UFOs,” which are the result of UFOs mixing with both the warm absorbers and loose matter floating between stars. Entrained UFOs are rare; this is only the sixth time one has ever been spotted, and only the first time one’s been spotted together with the other two kinds of outflows. The researchers said that the combined data tells a story about how UFOs interact with interstellar space.
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