Rapid changes observed in black hole winds

For the first time, astronomers have been able to observe the chemical and temperature changes in black hole winds occuring over a matter of hours.

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Artist's view of a supermassive black hole with X-ray emissions coming from its inner region (pink) and ultrafast winds (light purple) streaming from the surrounding disc.
Credits: ESA

Ultrafast winds flowing from a supermassive black hole have been observed for the first time heating up and cooling down within a matter of hours.

The observations, made using NASA's NuSTAR and ESA's XMM-Newton telescope, have revealed how these winds may affect the environment in which supermassive black holes reside.

Many galaxies, such as our own Milky Way, have a supermassive black hole at their centre. These objects are millions to billions of times more massive than the Sun, and they suck in cosmic material from a disc of gas and dust that surrounds them. This feeding creates an energy outflow that can be seen as X-ray emissions by using powerful space telescopes.

Sometimes the black hole may feed on so much material that it releases a strong wind of hot gas into space, which can disrupt the formation of stars and reshape the host galaxy.

 


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Scientists observed the supermassive black hole at the centre of galaxy IRAS 13224-3809 and its powerful winds over a period of 17 days in a row.

“We often only have one observation of a particular object, then several months or even years later we observe it again and see if there’s been a change,” says Michael Parker of the Institute of Astronomy at the University of Cambridge, lead author of the study. “Thanks to this long observation campaign, we observed changes in the winds on a timescale of less than an hour for the first time.”

The observations revealed winds coming from the black hole at 71,000 km per second, which is 0.24 times the speed of light. Changes were observed as an increase in the temperature and chemical makeup of the gas as the X-ray emissions increased.

“The chemical fingerprints of the wind changed with the strength of the X-rays in less than an hour, hundreds of times faster than ever seen before,” says Andrew Fabian, principal investigator of the project. “It allows us to link the X-ray emission arising from the infalling material into the black hole, to the variability of the outflowing wind farther away.”

By studying the changes in the wind and how they came about, the team hope to learn more about how supermassive black holes affect the structure of the galaxies in which they reside.


 

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