Black hole shock: Powerful 'UFO' blasts can reshape galaxies, NASA astronomers reveal

A collaboration between NASA and the European Space Agency (ESA) has revealed how supermassive black holes form their host galaxies with powerful winds that sweep away interstellar matter. NASA researchers analysed eight years of the ESA’s XMM-Newton X-ray observations of the black hole at the core of an galaxy PG 1114+445. This showed Ultra-Fast Outflows (UFOs) of gas emitted from the black hole interacted with the galaxy’s interstellar matter. And although these outflows have been spotted before, the new study is the first to clearly identify three phases of their interaction with the host galaxy.

The study’s lead author Dr Roberto Serafinelli, of the National Institute of Astrophysics in Milan, said: “These winds might explain some surprising correlations that scientists have known about for years but couldn’t explain.

“For example, we see a correlation between the masses of supermassive black holes and the velocity dispersion of stars in the inner parts of their host galaxies.

“But there is no way this could be due to the gravitational effect of the black hole.

“Our study for the first time shows how these black hole winds impact the galaxy on a larger scale, possibly providing the missing link.”

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Astronomers have previously detected two types of cosmic winds in the X-ray spectra emitted by the active galactic nuclei, the dense central regions of galaxies known to contain supermassive black holes.

The so-called UFOs are composed of highly-ionised gas, blowing at 40 percent the speed of light and are observable in the vicinity of the central black hole.

Slower outflows, referred to as warm absorbers, travel at much lower speeds of hundreds of kilometres a second and have similar physical characteristics.

These include particle density and ionisation of the surrounding interstellar matter.

These slower outflows are more likely to be detected at greater distances from the galaxy centres.

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In the new study, the scientists describe a third type of outflow that combines characteristics of the previous two: the speed of a UFO and the physical properties of a warm absorber.

Dr Serafinelli added: ”We believe that this is the point when the UFO touches the interstellar matter and sweeps it away like a snowplough.

“We call this an ‘entrained ultra-fast outflow’ because the UFO at this stage is penetrating the interstellar matter. It is similar to wind pushing boats in the sea.”

This entraining happens at a distance of tens to hundreds light years away from the black hole.

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The UFO gradually pushes the interstellar matter away from the central parts of the galaxy, clearing it from gas and slowing down the accretion of matter around the supermassive black hole.

While models have predicted this type of interaction before, the current study is the first to present actual observations of the three phases.

Co-author Francesco Tombesi of NASA’s Goddard Space Flight Centre, said: ”In the XMM-Newton data, we can see material at larger distances from the centre of the galaxy that hasn’t been disturbed yet by the inner UFO.

“We can also see clouds closer to the black hole, near the core of the galaxy, where the UFO has started interacting with the interstellar matter.”

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