Supermassive Black Hole in the Center of the Galaxy Erupted 2 Million Years Ago
The supermassive black hole located at the center of the Milky Way galaxy erupted in a massive explosion 2 million years ago, according to a new study published in The Astrophysical Journal.
The black hole's presence has been known for decades, with the region surrounding it, known as Sagittarius A*, emitting radio waves, infrared, X-rays and gamma rays.
However, for years evidence has been building of a past cataclysmic event, expressed in the powerful outflow of material from the region.
"All this points to a huge explosion at the [center] of our Galaxy," team member Philip Maloney of the University of Colorado, said in a statement.
The "smoking gun," came in the form of the Magellanic Stream -- a lacy filament of gas largely comprised of hydrogen trailing behind the Milky Way's neighbors, the Large and Small Magellanic Clouds.
"For twenty years we've seen this odd glow from the Magellanic Stream," said Joss Bland-Hawthorn, a researcher from the University of Sydney and study leader. "We didn't understand the cause. Then suddenly we [realized] it must be the mark, the fossil record, of a huge outburst of energy from the center of our Galaxy."
Illuminated by the outpouring of material from Sagittarius A*, the stream's ultraviolet light splits hydrogen atoms into protons and electrons that, upon reuniting, cause the electrons to give off "H-alpha" emissions, a specific wavelength of light.
The brightest portion of the glow, the researchers found, in the region nearest the Galactic Center.
As Bland-Hawthorn points out, the Milky Way's stars don't produce the ultraviolet light that would account for such a bright glow, nor did they in the past.
"The Galactic [Center] never formed stars at a high enough rate."
As to whether such an explosion could ever happen again, Bland Hawthorn said: "There are lots of stars and gas clouds that could fall onto the hot disk around the black hole. There's a gas cloud called G2 that we think will fall in next year. It's small, but we're looking forward to the fireworks!"