The Supermassive Black Hole at Milky Way Center Brightens and Fades --New Observations Show Why

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The normally quiet neighborhood around the massive black hole at the center of our Milky Way Galaxy is being invaded by a gas cloud that is destined in just a few years to be ripped, shredded and largely eaten.

The image above shows a simulation of how a gas cloud that has been observed approaching the supermassive black hole at the center of the Mily Way may break apart over the next few years. This is the first time ever that the approach of such a doomed cloud to a supermassive black hole has been observed and it is expected to break up completely during 2013.

The remains of the gas cloud are shown in red and yellow, with the cloud's orbit marked in red. The stars orbiting the black hole are also shown along with blue lines marking their orbits. This view simulates the expected positions of the stars and gas cloud in the year 2021.

"When we look at the black holes in the centers of other galaxies, we see them get bright and then fade, but we never know what is actually happening," said Eliot Quataert, a theoretical astrophysicist and University of California, Berkeley professor of astronomy.

"This is an unprecedented opportunity to obtain unique observations and insight into the processes that go on as gas falls into a black hole, heats up and emits light. It's a neat window onto a black hole that's actually capturing gas as it spirals in."

"The next two years will be very interesting and should provide us with extremely valuable information on the behavior of matter around such massive objects, and its ultimate fate," said Reinhard Genzel, professor of physics at both UC Berkeley and the Max Planck Institute for Extraterrestrial Physics (MPE) in Garching, Germany.

The discovery by Genzel; Stefan Gillessen of the MPE; Quataert and colleagues from Germany, Chile and Illinois will be reported online Wednesday, Dec. 14, in advance of the Jan. 5 publication of the news in the British journal Nature.

Since 2008. Genzel, Gillessen, Quataert and their team have seen the gas cloud about three times the mass of Earth speeding up as it has fallen deeper into the gravitational whirlpool of the black hole. Its edges are already beginning to fray.

"It is not going to survive the experience," said first author Gillessen. He built the infrared detector on the European Southern Observatory's Very Large Telescope in Chile used to observe the movement of stars and gas in the center of the Milky Way, 27,000 light years from Earth.

By 2013, scientists should see outbursts of X-rays and radio waves as the cloud – composed mostly hydrogen and helium gas gets hotter and is torn asunder. The light emitted around the black hole could increase by a hundredfold to a thousandfold, Quataert calculated. The Chandra X-ray satellite has already scheduled its largest single chunk of observation time in 2012 near the Milky Way's central black hole.

Astronomers have long observed clouds of gas streaming toward the center of our Milky Way Galaxy, presumably destined to fall into the 4.3 million solar-mass black hole lurking there. But this black hole "has a surprisingly low amount of matter falling inward at the moment," Quataert said.

Since MPE astronomers began observing the black hole in 1992, they have seen only two stars as close as this gas cloud to the black hole. The crucial difference is that those stars "passed unharmed through their closest approach, (while) the gas cloud will be completely ripped apart by the tidal forces around the black hole," Gillessen said.

This particular cold cloud (about 550 Kelvin or 280 degrees Celsius) may have formed when gas pushed by stellar winds from two nearby stars collided, and is glowing under the strong ultraviolet radiation from surrounding hot stars. As the cloud skirts the gravitational influence of the black hole, it will come within about 40 billion kilometers 250 times the distance between Earth and the sun of the event horizon, the limit beyond which nothing, not even light, can escape.

Even at that distance, the gas will get stretched out, with probably half spiraling into the black hole and the rest flung outward.

As the cloud falls towards the black hole – its current velocity is about 2,350 kilometers per second, twice what it was seven years ago – it will interact with the hot gas present in the accretion flow around the black hole and become disrupted by turbulent interaction.

Thanks to the Very Large Telescope's years of observations of the black hole at many different wavelengths, the scientists were able simulate the time evolution of the cloud and predict that the temperature of the gas cloud should increase rapidly to several million Kelvin near the black hole, dramatically increasing X-ray emissions.


The Daily Galaxy via University of California - Berkeley

QUOTE: Paul Laviolette's work is extensive in areas such as cosmology, physics, astronomy, climatology and geology. His work has taken him into studying ancient cosmic cataclysmic cycles, Galactic Core Explosions, Black Holes, Gamma Ray Bursts, Subquantum Kinetics and the decoding of the Sphinx Stargate zodiac cryptogram. He received his Bachelor of Arts in physics from Johns Hopkins University, his Masters in Business Administration from the University of Chicago, and a PhD from Portland State University and is currently president of the Starburst Foundation. He's written: "Earth Under Fire: Humanity's Survival of the Ice Age", "Genesis of the Cosmos - The Ancient Science of Continuous Creation", "Secrets of Antigravity Propulsion: Tesla, UFO's and Classified Aerospace Technology", "The Talk of the Galaxy: An ET message for us?" and "Decoding the Message of the Pulsars". Paul joins us for one hour to introduce us to his work. We dive into "Earth Under Fire" first and talk about the ice age, galactic superwave theory, myths and legends about these events in the past. We move on to discuss "Intelligent Design of the Cosmos" and suppression of this kind of scientific work. We also spend time talking about his latest studies on Subquantum Kinetics. Topics Discussed: Earth Under Fire, CME, Cosmic Dust, Sun Encrusted, Sun Explosion, Time Capsule Message, Center of Our Galaxy, 25000 Thousand Year Cycle, Iridium, Nickel, Gold, Galactic Superwave Theory, Big Bang Theory Disproven, Decoding the Message of the Pulsars - Intelligent Communication from the Galaxy, Cosmic Rays, Galaxy Explode, Creating Dust, Extinction Event, Gamma Ray Burst, Bull, Knossos, Create, Minoan, Pleiades, T Tauri Stars, Solar Flares, Subquantum Kinetics, Magic and more.

14 December 2011 by Stephen Battersby

The sleeping giant at the centre of the Milky Way is about to wake up. A suicidal gas cloud is heading towards the galaxy's supermassive black hole, which will probably swallow the cloud, generating enormous flares of radiation that could help explain why the black hole is normally so placid.

The doomed cloud was a surprise to astronomers. "We have been looking at the galactic centre for 20 years, but mainly to observe the motion of stars," says Reinhard Genzel of the Max Planck Institute for Extraterrestrial Physics in Garching, Germany.

Genzel's colleague Stefan Gillessen spotted the cloud in images from the Very Large Telescope array in Chile, taken in March this year. It is an unusually dense cloud, not much bigger than our solar system and carrying about three times the mass of Earth.

Shredded cloud

The team realised that the cloud also appears in earlier images, giving them a sequence that reveals its path. It is moving at almost 2500 kilometres per second towards our galaxy's black hole, Sagittarius A*.

At present Sagittarius A* is strangely quiet, unlike quasars, the hyperactive black holes that emit huge amounts of radiation, fuelled by inflowing gas. Our black hole gets much less gas, and for some reason this starvation state makes it much less efficient than a quasar, producing only a thousandth as much radiation per kilogram of fuel.

While a star would just sail past our black hole unscathed, the loose mass of gas heading towards it is more vulnerable. It is already being stretched out by the black hole's gravity, and when it gets closer in 2013 it will plough into the halo of hot gas around the hole.

Unlucky timing

That should send shockwaves through the cloud to heat it to several million degrees, and according to the group's simulations the gaseous collision will shred the cloud into filaments. This turmoil may mean that much of the cloud ends up swirling right down into the black hole.

"By dumping more material in there, the cloud could drive the system into a higher efficiency regime," says Ginzel. There may be one huge flare of radiation or several over the coming decades.

There's no danger of the active black hole harming Earth. And though sadly not visible to the naked eye, this radiation will give astronomers clues as to why our black hole is normally so different from quasars.

"There is evidence that the galactic centre was more luminous within the last few thousand years, and we are unlucky in living at a time when it appears to be unusually dormant," says astrophysicist Martin Rees at the University of Cambridge, who was not part of the study.

Journal reference: Nature, DOI: 10.1038/nature10652

Researchers have spotted a giant gas cloud spiralling into the supermassive black hole at our galaxy’s centre.

Though it is known that black holes draw in everything nearby, it will be the first chance to see one consume such a cloud.

As it is torn apart, the turbulent area around the black hole will become unusually bright, giving astronomers a chance to learn more about it.

The cloud, which is described in Nature, should meet its end in 2013.

Researchers using the European Southern Observatory’s Very Large Telescope estimate that despite its size, the cloud has a total mass of only about three times that of Earth.

They have plotted the cloud’s squashed, oval-shaped path and estimate it has doubled its speed in the last seven years – to 2,350km per second.

It should spiral in to within about 40 billion kilometres of the black hole in the middle of 2013.

Our local supermassive black hole, dubbed Sagittarius A*, lies about 27,000 light-years away, and has a mass about four million times that of our Sun.

As the name implies, beyond a certain threshold point – the event horizon – nothing can escape its pull, not even light itself.

But outside that regime is a swirling mass of material, not unlike water circling a drain. In astronomical terms, is a relatively quiet zone about which little is known.

That looks set to change, though, as the gas cloud approaches.

Spaghetti tester

It does not comprise enough matter to hold itself together under its own gravity, as a star might, so the cloud will begin to elongate as it meets its doom.

“The idea of an astronaut close to a black hole being stretched out to resemble spaghetti is familiar from science fiction,” said lead author of the study Stefan Gillessen, from Max Planck Institute for Extraterrestrial Physics in Germany.

“But we can now see this happening for real to the newly discovered cloud. It is not going to survive the experience.”

It is likely that about half of the cloud will be swallowed up, with the remainder flung back out into space.

But this violent process will literally shed light on the closest example we have of an enigmatic celestial object.

The acceleration of the cloud’s constituent material will create a shower of X-rays that will help astronomers learn more about our local black hole.

As astronomer Mark Morris of the University of California Los Angeles put it in an accompanying article in Nature, “many telescopes are likely to be watching”.

http://www.bbc.co.uk - http://www.eso.org

Black hole extravaganza in 1080p. From ESOcast. Not long ago, watching something being ripped apart as it falls towards a giant black hole would be science fiction. This is now reality. Observers under dark skies, far from the bright city lights, can marvel at the splendor of the Milky Way, arching in an imposing band across the sky. Zooming in towards the center of our galaxy, about 25000 light years away, you can see that it is composed of myriads of stars.

This is a pretty impressive sight, but much is hidden from view by interstellar dust, and astronomers need to look using a different wavelength, the infrared, that can penetrate the dust clouds. With large telescopes, astronomers can then see in detail the swarm of stars circling the supermassive black hole, in the same way that the Earth orbits the Sun.

The Galactic Center harbors the closest supermassive black hole known, and the one that is also the largest in terms of its angular diameter on the sky, making it the best choice for a detailed study of black holes.

This black hole's mass is a hefty four million times that of the Sun, earning it the title of supermassive black hole. Although it is huge, this black hole is currently supplied with little material and is not shining brightly. But this is about to change.

Using ESO's Very Large Telescope, a team of astronomers has discovered a new object that is heading almost straight towards the black hole at vertiginous speed. The object is not a star, but a cloud of gas.

"The cloud consists mainly of hydrogen gas, gas which we see anyhow in the galactic center all over the place. This particular cloud weighs more or less three times the mass of Earth. So it's a rather small and tiny blob only, but it glows very brightly in the light of the stars which are surrounding it ."

As the astronomers watch, the cloud has been picking up pace as it gets closer to the giant black hole. Its speed has doubled in the last seven years and it is now speeding towards the black hole at more than 8 million kilometers per hour.

The astronomers have already seen the cloud's outer layers becoming more and more disrupted over the last few years as it approaches the black hole. But the exciting part is yet to come.

"The Black hole, imagine it sitting here, has a tremendous gravitational force and the cloud, as it comes in, it will be elongated and stretched, it will become essentially like spaghetti. It will be elongated and falling into the black hole."

"The next few years will be really fantastic and exciting because we are probing the territory. Here this cloud comes and gets disrupted, but now it will begin to interact with the hot gas right around the black hole. We have never seen this before."

No one knows what will happen next. The cloud will probably heat up and may start to emit powerful X- rays as it gets disrupted. In the end the material will eventually disappear by falling into the black hole. For the scientists, this event is truly a unique chance to probe the hot gas around the black hole.

"But this process of how material gets into the black hole really is not clear to us we don't understand it in any detail. And here in the galactic center we have an opportunity so to speak to have a probe of this process. How material really gets added to the black hole, and what the physical processes are, how the interactions happen in this very central region. That's a fantastic opportunity."

This is indeed science fiction becoming science fact.