Astronomers discover that our galaxy’s black hole is unpredictable and chaotic

An analysis of 15 years of data has not found a clear pattern in the activity of Sagittarius A, the black hole in the center of the Milky Way, making it unpredictable and chaotic.

Sagittarius A is a strong source of radio, X-rays, and gamma rays (visible light is blocked by intervening gas and dust). Astronomers have known for decades that Sagittarius A blinks every day, emitting bursts of radiation that are ten to one hundred times brighter than the stars.

To learn more about these mysterious flashes, a team of astronomers, led by Alexis Andrés, a Salvadoran student at the University of Amsterdam, looked for patterns in 15 years of data available from NASA’s Neil Gehrels Swift Observatory, an orbiting satellite. dedicated to the detection of gamma ray bursts. The findings are published in Monthly Notices of the Royal Astronomical Society.

The Swift Observatory has been observing gamma rays from the black hole since 2006. Analysis of the data showed high levels of activity between 2006 and 2008, with a sharp decline in activity over the next four years. After 2012,; the researchers had difficulty distinguishing a pattern.

In the next few years, the team of astronomers hope to collect enough data to be able to rule out whether the variations in the eruptions of Sagittarius A are due to the passage of gaseous clouds or stars, or if something else can explain the irregular activity observed in the central black hole. of our galaxy.

“The long data set from the Swift Observatory did not happen by accident,” Andres co-author and former supervisor Dr. Nathalie Degenaar, also at the University of Amsterdam, says in a statement. Your request for these specific Swift satellite measurements was granted while you were studying for your doctorate. “Since then, I have been requesting more observation time on a regular basis. It is a very special observation program that

Co-author Dr Jakob van den Eijnden of the University of Oxford comments on the team’s findings: “It is not yet clear how exactly the eruptions occur. It was previously thought that more eruptions followed after stars or gaseous clouds passed through the black hole but there is no evidence for that yet. And we still cannot confirm the hypothesis that the magnetic properties of the surrounding gas do not play a role either. “

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