According to a news release on Sept. 25 from researchers from the University of Sydney, the Milky Way’s supermassive black hole flamed so brightly that it outshone the moon two million years ago and they now believe they know the reason.
The area around the galaxy’s supermassive black hole and the black hole itself is known as Sagittarius A*. Scientists describe the supermassive black hole as a “dormant volcano”.
Like volcanos, black holes can erupt, actually flare-ups due to the absorption of stars and gas clouds by the black hole. Blasts of energy in the form of light can jet out of black holes and scientists warn that there are lots of meteors, stars and gas clouds circling our galactic centre.
In fact next year scientists predict that a massive gas cloud they have been monitoring will fall into into the black hole and light up the sky. This is exactly what happened two million years ago.
New research has proved what happened then and what will happen next year when a two large gas flares go near the hole.
"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," said Professor Joss Bland-Hawthorn, author of an article on the research to be published in the upcoming Astrophysical Journal.
The proof for the discoveries originates from a lacy filament of hydrogen gas known as the Magellanic Stream. It trails behind the Milky Way’s two tiny companion galaxies, the Large and Small Magellanic Clouds. In other words, the glow that follows the Milky Way are the remnants of flare-ups from the black hole.
“Since 1996, we’ve been aware of an odd glow from the Magellanic Stream, but didn’t understand the cause. Then this year, it finally dawned on me that it must be the mark, the fossil record, of a huge outburst of energy from the supermassive black hole at the centre of our galaxy,” said Martin Rees, Astronomer Royal.
According to Bland-Hawthorn, NASA’s Fermi satellite found two large bubbles of hot gas surging out from the center of the galaxy in 2010. The bubbles blanketed nearly a quarter of the sky.
Computer simulations of the Fermi bubbles revealed that they were brought about by a large explosion from the Milky Way’s supermassive black hole within the last few million years.
“I calculated that to explain the glow it must have happened two million years ago because the energy release shown by the Santa Cruz group perfectly matched, to our delight, that from the Magellanic Stream,” Bland-Hawthorn said.
One thing people may not know is that black holes spin which create the gravitational pull but the ultraheated rim of particles that remains around the hole help to start to burn the gas clouds that come close.
According to the researchers, there is a chance that the humongous explosion could happen again. In fact, a gas cloud known as G2 is expected to fall onto the black hole sometime next year. Greg Madsen, astronomer at the University of Cambridge reassures the public though.
"It will be much fainter and will pose no threat to Earth, but several powerful telescopes will be poised and ready to watch what happens."