An international research team led by graduate student Alexis Andres found that
“>Black hole At the center of our galaxy, Sagittarius A*, it shines 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 his research in 2019 while a summer student at the University of Amsterdam. In the following years, 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 irritating 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 signal observed from a black hole.
To learn more about this mysterious beacon, a team of astronomers led by Andres looked for patterns in 15 years of data provided by Andres.
“> NASANeil Geirels Swift Observatory, 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 shows high levels of activity from 2006 to 2008, with a sharp decline in activity over the next four years. After 2012, the frequency of flares increased again – the researchers had a hard time distinguishing the patterns.
In the next few years, the team of astronomers hope to gather enough data to be able to rule out whether the flare difference from Sagittarius A* is due to a gas cloud or passing star, or if something else could explain the irregular activity observed from the central black hole. in our galaxy.
“The long data set from the Swift Observatory did not happen by accident,” said co-author and former supervisor of Andrés, Dr Nathalie Degenaar, also at the University of Amsterdam. His request for this particular measurement from the Swift satellite was approved when he was a doctoral student. “Since then, I have applied for more monitoring time on a regular basis. This is a very specialized monitoring program that allows us to do a lot of research.”
Co-authored by Dr. Jacob van den Igenden, or
Article: Oxford UniversityCommenting on the team’s findings: “How the flare occurs is still not completely clear. It was previously believed that more flares came after the gas cloud or star passed through the black hole, but there is no evidence for this yet. We haven’t been able to confirm the hypothesis that the magnetic properties of the surrounding gas also play a role.”
Reference: “A Fast Study of long-term changes in the combustion properties of X-ray arcs A” by A Andrés, J van den Eijnden, N Degenaar, PA 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