The black hole at the center of the Milky Way is...

An international team of researchers led by graduate student Alexis Andres An has discovered Black hole At the center of our galaxy, Sagittarius A*, it erupts not only irregularly from day to day but also over the long term. The team analyzed 15 years of data to come to this conclusion. Andres began research in 2019 when he was a summer student at the University of Amsterdam. In the years that followed, he continued his research, which will now be published in Monthly Notices of the Royal Astronomical Society.

Arc A* is a powerful source of radio, X-rays and gamma rays (visible light is blocked by interfering gases and dust). Astronomers have known for decades that Sagittarius A* flashes daily, emitting bursts of radiation ten to a hundred times brighter than the normal signals seen from a black hole.

This X-ray image of the galactic center merges all of Swift’s observations from 2006 to 2013. Sagittarius A* is in the center. Low-energy X-rays (300 to 1500 MeV) are shown in red. Greens are of medium power (1500 to 3000 volts). Blues music is high energy (3,000 to 10,000 MeV). Credit: NASA/Swift/In. deigner

To learn more about these mysterious eruptions, a team of astronomers led by Andres searched for patterns in 15 years of data made available by Andres. NASANeil Gehrells Swift Observatory, an Earth-orbiting satellite dedicated to detecting gamma ray bursts. The Swift Observatory has been observing gamma rays from the black hole since 2006. Analysis of the data showed high levels of activity from 2006 to 2008, with a sharp decline in activity over the next four years. After 2012, the frequency of eruptions increased again – researchers have struggled to discern the pattern.

Over the next few years, the team of astronomers hopes to gather enough data to be able to rule out whether the differences in the flares of Sagittarius A* are caused by passing gas clouds or stars, or something else. They may explain the irregular activity observed. From the central black hole of our galaxy.

“The long data set of the Swift Observatory did not happen by chance,” says co-author Andres and former supervisor, Dr. Nathalie DeGeneres, also at the University of Amsterdam. Her request to get these specific measurements from the Swift satellite was approved when she was a doctoral student. “Since then, I regularly request more observation time. It is a very special monitoring program that allows us to do a lot of research.

Co-author Oxford universityCommenting on the team’s findings: “How the eruptions occurred is still unclear. It was previously thought that more flares would follow after gas clouds or stars passed through the black hole, but there is no evidence for this yet. We cannot yet confirm the hypothesis that the magnetic properties of the surrounding gas also play a role.

Reference: “A Fast Study of long-term changes in X-ray glow properties of arc A” by A Andrés, J van den Eijnden, N Degenaar, P. A. Evans, K Chatterjee, M Reynolds, JM Miller, J Kennea, R Wijnands, S Markoff, D Altamirano, CO Heinke , A Bahramian and G Ponti, D Haggard, 9 Dec 2021, Available here. Monthly Notices of the Royal Astronomical Society.
DOI: 10.1093 / mnras / stab3407