Highly Energetic Explosion Occurred in Milky Way’s Center 3.5 Million Years Ago | Astronomy – Sci-News.com
About 3.5 million years ago, a Seyfert flare from Sagittarius A*, a supermassive black hole in the center of the Milky Way Galaxy, created two enormous ionization cones that sliced through our Galaxy, beginning with a relatively small diameter close to the black hole, and expanding vastly as they exited the Galaxy.
An artist’s impression of the massive bursts of ionizing radiation exploding from the center of the Milky Way and impacting the Magellanic Stream. Image credit: James Josephides / ASTRO 3D.
“The flare must have been a bit like a lighthouse beam,” said Professor Joss Bland-Hawthorn, from the University of Sydney and the ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D).
“Imagine darkness, and then someone switches on a lighthouse beacon for a brief period of time.”
Using data from the NASA/ESA Hubble Space Telescope, Professor Bland-Hawthorn and colleagues calculated that the massive explosion took place little more than three million years ago.
“In Galactic terms, that is astonishingly recent,” they noted.
“On Earth at that point, the asteroid that triggered the extinction of the dinosaurs was already 63 million years in the past, and humanity’s ancient ancestors, the Australopithecines, were afoot in Africa.”
“This is a dramatic event that happened a few million years ago in the Milky Way’s history,” added Professor Lisa Kewley, Director of ASTRO 3D.
“A massive blast of energy and radiation came right out of the Galactic center and into the surrounding material. This shows that the center of the Milky Way is a much more dynamic place than we had previously thought. It is lucky we’re not residing there!”
According to the team, the Seyfert flare lasted for perhaps 300,000 years and was so powerful that it impacted on the Magellanic Stream, a long trail of gas extending from nearby Large and Small Magellanic Clouds.
“These results dramatically change our understanding of the Milky Way,” said Dr. Magda Guglielmo, from the University of Sydney.
“We always thought about our Galaxy as an inactive galaxy, with a not so bright center. These new results instead open the possibility of a complete reinterpretation of its evolution and nature.”
“The flare event that occurred 3.5 million years ago was so powerful that it had consequences on the surrounding of our Galaxy. We are the witness to the awakening of the sleeping beauty.”
The research will be published in the Astrophysical Journal.
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Joss Bland-Hawthorn et al. 2019. The Large-Scale Ionization Cones in the Galaxy. ApJ, in press;
