Black hole at center of Milky Way unpredictable and chaotic

Swift observations from 2006 through 2013 are merged into an X-ray image of the galactic center. The center of Sagittarius A* is there. The low-energy X-rays are red. Medium-energy green are between 1,500 and 3000 eV. Blue have high energy levels. Credit: NASA/Swift.

The black hole at the center of our universe, Sagittarius A*, flares from day to day but also in the long term, according to an international team of researchers. 15 years' worth of data was analyzed to come to this conclusion. When he was a summer student at the University of Amsterdam, Andres started the research. He continued his research for many years after that, and his work is now to be published in Monthly Notices of the Royal Astronomical Society.

Sagittarius A* is a strong source of radio, X-rays and gamma rays. Astronomers have known for decades that Sagittarius A* flashes every day, emitting bursts of radiation that are ten to a hundred times brighter than normal signals from the black hole.

To find out more about the flares, the team of Astronomers, led by Andrés, searched for patterns in 15 years of data from NASA's Neil Gehrels Swift Observatory. Since 2006 the Swift Observatory has been observing the rays from the black hole. The data showed high levels of activity from 2006 to 2008 but a decline in activity over the next four years. The researchers had a hard time distinguishing a pattern after the flares increased again.

In the next few years, the team of astronomer expect to gather enough data to be able to rule out either the passing of clouds or stars or something else as the cause of the flares from Sagittarius A*.

The long dataset of the Swift observatory did not just happen by accident, says co-author and previous supervisor to Andrés, Dr. Nathalie Degenaar. She was a student at the time she requested the Swift satellite measurements. I've been applying for more observing time. It's a very special observing program that allows us to conduct a lot of research.

Dr. van den Eijnden commented on the team's findings, saying that how the flares occur is unclear. There is no evidence that more flares follow after a black hole is passed by clouds or stars. The magnetic properties of the surrounding gas can play a role.

A Swift study of long-term changes in the X-ray flaring properties of Sagittarius A* was published in the Monthly Notices of the Royal Astronomical Society. There is a book titled "10093/mnras/stab3407".

There are monthly Notices of the Royal Astronomical Society.

There is a black hole at the center of the Milky Way.

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