Like most galaxies, the Milky Way has a supermassive black hole in its
center. For the most part, however, that black hole is dormant – meaning
that it isn’t emitting large amounts of radiation. That’s because that
radition, in the form of X-rays, gamma rays, radio waves, is emitted
when large objects – like giant gas clouds or stars – are brought into
the black hole’s gravitational field. Matter falling into the black hole
is subjected to exceedingly large gravitational forces, and the result
is a blaze of light and radiation that is very visible to telescopes.
However, a team of scientists has uncovered evidence that two million years ago – when humanity’s earliest ancestors newly stepped on the world – the supermassive black hole in the center of our galaxy, Sagittarius A*, erupted in an explosion of high-energy radiation called a “Seyfert flare.” During that time, the radiation from the black hole was about 100 million times more powerful than it is today. Our ancestors may have even see the huge burst of light themselves, but this was hundreds of thousands of years before any kind of human was taking notes.
Astronomers have seen signs that there was such a Seyfert flare for the past few years, in the form of antimatter radiation and other clues. However, this new research enables astronomers to closely date when that explosion could have happened.
The key the astronomers found was actually discovered 20 years old, in the form of a strange glow that astronomers had noticed in the Magellanic Stream. The Magellanic Stream is composed of large clouds of gas – mostly hydrogen – that stretch for light years in the wake of the Milky Way’s two companion Galaxies, the Large and Small Magellanic Clouds. The Stream is about 2 billion years old.
“We didn’t understand the cause. Then suddenly we realised it must be the mark, the fossil record, of a huge outburst of energy from the centre of our Galaxy,” remarked researcher Joss Bland-Hawthorn in a press release.
As the radiation traveled from the explosion at the heart of our galaxy, it eventually hit the Magellanic Stream, where the high energy hitting the gas clouds caused them to light up, the same way cosmic radiation causes auroras here on Earth.
Having arrived at that thought, the astronomers then crunched the numbers, using complicated geometries to figure out the direction of a potential eruption. Then they determined how long it would take the radiation to get to the Magellanic Stream, then how long it would take for the light from that explosion to then be visible here on Earth. Based on those calculations, the eruption most likely occurred about 2 million years ago.
The team also considered a number of other alternative sources for the glow, and found that they were far less likely due to the amount of energies involved. Additionally, these findings are consistent with the other signs of an eruption of Sagittarius A* that have been discovered in recent years.
“All this points to a huge explosion at the centre of our Galaxy,” said researcher Philip Maloney.
Read more : http://www.forbes.com/sites/alexknapp/2013/09/25/the-milky-ways-supermassive-black-hole-erupted-two-million-years-ago
However, a team of scientists has uncovered evidence that two million years ago – when humanity’s earliest ancestors newly stepped on the world – the supermassive black hole in the center of our galaxy, Sagittarius A*, erupted in an explosion of high-energy radiation called a “Seyfert flare.” During that time, the radiation from the black hole was about 100 million times more powerful than it is today. Our ancestors may have even see the huge burst of light themselves, but this was hundreds of thousands of years before any kind of human was taking notes.
Astronomers have seen signs that there was such a Seyfert flare for the past few years, in the form of antimatter radiation and other clues. However, this new research enables astronomers to closely date when that explosion could have happened.
The key the astronomers found was actually discovered 20 years old, in the form of a strange glow that astronomers had noticed in the Magellanic Stream. The Magellanic Stream is composed of large clouds of gas – mostly hydrogen – that stretch for light years in the wake of the Milky Way’s two companion Galaxies, the Large and Small Magellanic Clouds. The Stream is about 2 billion years old.
“We didn’t understand the cause. Then suddenly we realised it must be the mark, the fossil record, of a huge outburst of energy from the centre of our Galaxy,” remarked researcher Joss Bland-Hawthorn in a press release.
As the radiation traveled from the explosion at the heart of our galaxy, it eventually hit the Magellanic Stream, where the high energy hitting the gas clouds caused them to light up, the same way cosmic radiation causes auroras here on Earth.
Having arrived at that thought, the astronomers then crunched the numbers, using complicated geometries to figure out the direction of a potential eruption. Then they determined how long it would take the radiation to get to the Magellanic Stream, then how long it would take for the light from that explosion to then be visible here on Earth. Based on those calculations, the eruption most likely occurred about 2 million years ago.
The team also considered a number of other alternative sources for the glow, and found that they were far less likely due to the amount of energies involved. Additionally, these findings are consistent with the other signs of an eruption of Sagittarius A* that have been discovered in recent years.
“All this points to a huge explosion at the centre of our Galaxy,” said researcher Philip Maloney.
Read more : http://www.forbes.com/sites/alexknapp/2013/09/25/the-milky-ways-supermassive-black-hole-erupted-two-million-years-ago
.jpg)
0 comments:
Post a Comment