The first people to see the light of the black hole in the night sky




Supermassive black hole at the center of our galaxy could break out around 2 million years ago, around the time when our ancestors learned to walk straight along the ground. The light appeared in the night sky and became a serious competitor to the moon in brightness and size. More like a mushroom in shape than a sphere, the glow of a supermassive black hole at the heart of our galaxy implemented.

This colorful story was told at a conference in Sydney, Australia, this week, and tied together two seemingly unrelated pieces of galactic puzzle.

Besides the good solutions for both puzzles, he offered us an unexpected version of how space could seem earthlings 2 million years ago.

“It is when Homo erectus was running on Earth” – emphasizes Joss Bland-Hawthorn, who heads a team of researchers of this issue.

Also, the story describes the supermassive black hole as unpredictable and capable of generating the brightest flash in the universe in the blink of an eye. That, in turn, brings the modern people to take the risk sometime in the future. Fortunately, we are far from such a flash.

Bursting bubbles

It may seem odd that we’re talking about a supermassive black hole as the source of the brightest light in the universe. But it is precisely for this reason that some of the centers of galaxies, known as “active galactic nuclei”, shine so bright. The bottom line is that, as the black hole sucks matter, the matter is going to drive around the hole, heats up and begins to glow. When large volumes of material are pulled together into a disc, the black hole emits a bright jet, ie a jet of particles perpendicular to the axis of the black hole.

The central black hole Milky Way, Sagittarius A *, are now behaving obediently, but no one knows for sure what caused the black hole turn into an active galactic nucleus. One of the options – our galaxy was not always quiet – appeared in 2010, when astronomers using the Fermi satellite caught some mysterious entity called the Fermi bubbles, located on 25,000 light years above and below the plane of the galaxy. Theories that explain bubbles, ranging from gamma rays emitted by the annihilation of dark matter, to supersonic winds generated by intense bursts of star formation.

In April, at a meeting at Stanford University in California, Bill Matthews and Fula Guo University of California at Santa Cruz said that the bubbles were caused by the explosion of Sagittarius A *. Simulation of scientists found that two intensive jet of high-energy particles, such as those that produce an active galactic nucleus, from the vicinity of the black hole could produce these bubbles. Outbreak, according to scientists, occurred between 1 and 3 million years ago and lasted for several hundred thousand years.

Bland-Hawthorn, who was present at the announcement, heard it, and immediately realized that such a surge can resolve another ancient secret. In 1996, astronomers discovered that the part of the Magellanic Stream – fast moving stream of mostly hydrogen, 240 000 light-years from the Milky Way – lights is 10-50 times brighter than the rest.

Light hydrogen

Can the answer to this question is the same explosion that gave birth to the Fermi bubbles? After all, the brightest part of the flow is below the center of the galaxy.

To investigate the Bland-Hawthorn joined with other astronomers, including Gregory Madsen from Cambridge University, who for years has studied Magellanic Stream.

“Our telescope collected indications that at some point a large amount of UV rays can illuminate the flow,” – says Madsen. The explosion of UV radiation may explain why some of the flow of light, as it would have torn the hydrogen atoms, and those subsequently regrouped, emitting light in the course of this action.

Based on data from other galaxies with supermassive black holes that are actively emit jets, the scientists developed a theory that if Sagittarius A * was as active, ionized ultraviolet light – and thus set fire – part Magellanic Stream.

They then calculated the time and energy of the explosion, based on the time it will take to ultraviolet light to get to the stream, the recession hydrogen emission intensity over time, and the time it takes the radiation to reach us. This work perfectly coincided with the work of Matthews and Go.

Terrible delight

Active galactic nucleus of our galaxy 2 million years ago, in theory allows two puzzles at the same time. Moreover, it may well support the development of supermassive black holes.

Many theorists say that an active galactic nucleus is obtained only when galaxies merge. But the Milky Way does not compete with any of galaxies over billions of years, so there is the possibility of AGN in different conditions.

This, in turn, is reduced to the most recent works by Greg Novak of the Paris Observatory in France and Jeremiah Ostrikera from Princeton University. They suggest that active galactic nucleus can be generated by galactic gas moving in after a strong cooling and unstable disks of gas and dust that are falling apart and falling into a black hole. This would make the outbreak of active nuclei are more chaotic and unpredictable.

Novak delighted with the final work.

“This means that a few million years ago – a moment in galactic terms – the Milky Way really have been a large outbreak of an active galactic nucleus. It’s amazing! “, – He said.

It is possible that Sagittarius A * can generate active nucleus again, says Bland-Hawthorn. This would have catastrophic consequences for all worlds near the galactic center. But modern humans as their ancestors would have seen a beautiful and strange looking. “You would be terribly excited,” – he said.

What types of saw a flash?

If the story is true, the Milky Way black hole erupted 2 million years ago, forming a bright spot the size of a moon in the southern hemisphere. Who or what have seen her?

Two million years ago, human evolution has come an important time, says anthropologist Chris Stringer of the Natural History Museum in London.

“It was the beginning of the genus Homo. Stone axes have already been invented, but the brain is just starting to grow. ”

Homo erectus appeared about 1.9 million years ago, so kind of a black hole would have caught it. Homo habilis, the most brainy our ancestor, too, would have looked with wide eyes. Even Australopithecus sediba, recently discovered in South Africa, could see an amazing event in the night sky.

Since the center of the galaxy is seen mainly in the southern latitudes, it would have seen the only living creatures that live south of 20 º above the equator. Most of our bipedal ancestors roamed in these latitudes.

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