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 red X-rays have low energy. Medium-energy green are between 1,500 and 3000 eV. Blue have high-energy (3,000 to 10,000 eV) in them. Credit: NASA/Swift.
The black hole at the center of the galaxy flares from day to day, but also in the long term. An analysis of 15 years of data by an international team of researchers led by a man from El Salvador revealed this. After finishing his summer internship at the University of Amsterdam in the summer of 2019, Andres began his research. The journal Monthly Notices of the Royal Astronomical Society will publish the research.
Astronomers have known for decades that Sagittarius A, the black hole in the center of the Milky Way, flashes every day and sometimes gets 10 to 100 times brighter than normal. An international team of astronomer searched for patterns in 15 years of data to find out more about Sagittarius A's flares. Since 2006 NASA's Swift satellite has been looking at the central black hole.
The area near the black hole was showing some signs from 2006 to 2008. Between 2008 and 2012 it was very quiet. Flares increased again after 2012
The researchers couldn't distinguish a pattern. "So how the flares occur is not clear," says co-author Jakob van den Eijnden. There is no evidence that more flares follow after a black hole is passed by. The magnetic properties of the surrounding gas can play a role.
The summer school is over.
The leader of the research was from El Salvador. He was an undergraduate student in the ASPIRE program at the University of Amsterdam. Talented students from countries with less academic development opportunities work on an astronomy project during the summer. After graduating from summer school, Andres returned to El Salvador and spent the next two years researching. The international research team was not able to travel because of the corona restrictions. In Mexico City, he has been studying for a master's degree in astronomy. He wants to become a professional astronomer in his home country.
The dataset is long.
The long dataset of the Swift observatory did not happen by accident, says co-author Nathalie Degenaar. She was the supervisor during the summer school. NASA granted Degenaar's request for the measurements while she was doing her PhD. I've been applying for prolongation regularly since then. It's a very special observing program that allows us to conduct a lot of research.
Over the next few years, the astronomer expects to gather enough data to be able to rule out a variety of reasons for the flares near Sagittarius A*.
Sagittarius A
The black hole at the center of the galaxy is located in the direction of the constellation Sagittarius as seen from Earth. The black hole's environment has been studied by Astronomers for years. Half of the prize in physics in 2020 went to researchers who had spent years tracking the stars that circle the black hole. An international team of astronomy, with a large share from the Netherlands, is trying to take a picture of the black hole using a telescope. The black hole in galaxy M87 is the first picture to be published in 2019.
Swift studied the X-ray flaring properties of Sagittarius A*. The Monthly Notices of the Royal Astronomical Society are accepted for publication.
There are monthly Notices of the Royal Astronomical Society.
There is a black hole in the center of the Milky Way that is unpredictable in the long term.
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