Black holes can easily be pigeonholed as massive, confusing cosmic phenomena with a voracious appetite, but new research shows these celestial enigmas have a certain level of finesse to their activities. Scientists studying a massive explosion that erupted from our Milky Way's supermassive black hole 2 million years ago found that black holes can switch between power levels, going from maximum output to a proverbial rest state in a relatively short period of time.
"It's been long suspected that our galactic center might have sporadically flared up in the past. These observations are a highly suggestive 'smoking gun,'" said Martin Rees, one of the astronomers involved in the University of Sydney-led study detailing the findings.
"The realization that these black holes can switch on and off within a million years, which given the universe is 14 billion years old means very rapidly, is a significant discovery," said lead author professor Joss Bland-Hawthorn.
Researchers puzzled over a strange glow in the Magellanic Stream, a hydrogen gas stream trailing our Milky Way's two companion galaxies, found that it correlated with a theorized cataclysmic event in Sagittarius A*, the region surrounding the supermassive black hole at the center of our galaxy. Radiation levels in Sagittarius A* indicate that there was a massive eruption 2 million years ago.
"In particular, in 2010 NASA's Fermi satellite discovered two huge bubbles of hot gas billowing out from the center of the galaxy, covering almost a quarter of the sky. When I saw this research I realized that this same event would also explain the mysterious glow that we see on the Magellanic Stream," Bland-Hawthorn said.
"For 20 years astronomers have suspected that such a significant outburst occurred, but now we know when this sleeping dragon, four million times the mass of the sun, awoke and breathed fire with 100 million times the power it has today."
You can read the full published study in The Astrophysical Journal.
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