Are 10,000 Black Holes Orbiting Sgr A* --The Milky Way's Active Galactic Center
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September 08, 2011

Are 10,000 Black Holes Orbiting Sgr A* --The Milky Way's Active Galactic Center


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A swarm of 10,000 or more black holes may be orbiting the Milky Way's supermassive black hole, according to results from NASA's Chandra X-ray Observatory. This would represent the highest concentration of black holes anywhere in the Galaxy. These relatively small, stellar-mass black holes, along with neutron stars, appear to have migrated into the Galactic Center over the course of several billion years.

The discovery was made as part of the Chandra X-Ray Space Observatory's monitoring of the region around Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way.

Among the thousands of X-ray sources detected within 70 light years of Sgr A*, Muno and his colleagues searched for those most likely to be active black holes and neutron stars by selecting only the brightest sources that also exhibited large variations in their X-ray output.  "Although the region around Sgr A* is crowded with stars, we expected that there was only a 20 percent chance that we would find even one X-ray binary within a three-light-year radius," said Muno. "The observed high concentration of these sources implies that a huge number of black holes and neutron stars have gathered in the center of the Galaxy."

Mark Morris, also of UCLA had predicted a decade ago that a process called dynamical friction would cause stellar black holes to sink toward the center of the Galaxy. Black holes are formed as remnants of the explosions of massive stars and have masses of about 10 suns. As black holes orbit the center of the Galaxy at a distance of several light years, they pull on surrounding stars, which pull back on the black holes. The net effect is that black holes spiral inward, and the low-mass stars move out. From the estimated number of stars and black holes in the Galactic Center region, dynamical friction is expected to produce a dense swarm of 20,000 black holes within three light years of Sgr A*. A similar effect is at work for neutron stars, but to a lesser extent because they have a lower mass.

Once black holes are concentrated near Sgr A*, they will have numerous close encounters with normal stars there, some of which are in binary star systems. The intense gravity of a black hole can induce an ordinary star to "change partners" and pair up with the black hole while ejecting its companion. This process and a similar one for neutron stars are expected to produce several hundreds of black hole and neutron star binary systems.

The black holes and neutron stars in the cluster are expected to gradually be swallowed by the supermassive black hole, Sgr A*, at a rate of about one every million years. At this rate, about 10,000 black holes and neutron stars would have been captured in a few billion years, adding about 3 percent to the mass of the central supermassive black hole, which is currently estimated to contain the mass of 3.7 million suns.

In the meantime, the acceleration of low-mass stars by black holes will eject low-mass stars from the central region. This expulsion will reduce the likelihood that normal stars will be captured by the central supermassive black hole. This may explain why the central regions of some galaxies, including the Milky Way, are fairly quiet even though they contain a supermassive black hole

The images are part of an ongoing Chandra program that monitors a region around the Milky Way's supermassive black hole, Sagittarius A* (Sgr A*). Four bright, variable X-ray sources (circles) were discovered within 3 light years of Sgr A* (the bright source just above Source C). The lower panel illustrates the strong variability of one of these sources. This variability, which is present in all the sources, is indicative of an X-ray binary system where a black hole or neutron star is pulling matter from a nearby companion star.

The black hole at the center of our Milky Way Galaxy is a monster that contains about 4 million times more material than our sun. But compared to the giant black holes in the centers of other galaxies, our black hole is strangely quiet.

A team of Japanese astronomers may have helped solve the mystery. By using four satellites that catch X-rays from outer space, they found evidence that our black hole suddenly emitted a powerful outburst of X-ray light 300 years ago

"We have wondered why the Milky Way’s black hole appears to be a slumbering giant," says team leader Tatsuya Inui of Kyoto University in Japan. "But now we realize that the black hole was far more active in the past. Perhaps it’s just resting after a major outburst."

The black hole itself is known as Sagittarius A* (pronounced "A-star"), for its location in the constellation Sagittarius. Normally, the black hole is quiet, producing billions of times less energy than giant black holes in other galaxies. But according to Inui and his colleagues, the black hole must have produced an incredible burst of X-ray light three centuries ago. They made this discovery by noticing a strange effect known as "light echoes."

Light echoes are similar to the sound echoes we hear when sound waves reverberate in a room or valley. In the case of light echoes, the X-rays produced by the giant outburst have been racing outward across trillions of miles of space at the speed of light. Three hundred years later, they have traveled far enough that they reach a giant gas cloud known as Sagittarius B2. Once they penetrate this cloud, they heat up the gas, and cause it to glow brightly in X-rays. But once the X-rays pass through the cloud, it cools down, and its brightness fades back to normal. Sagittarius B2 acts like a giant mirror. The light echoes inside the cloud give astronomers a record of the black hole’s energy output 300 years earlier.

By using Japan’s Suzaku and ASCA X-ray satellites, NASA’s Chandra X-ray Observatory, and the European Space Agency’s XMM-Newton X-ray Observatory, Inui’s team could observe the behavior of the cloud.

"By observing how this cloud lit up and faded over 10 years, we could trace back the black hole’s activity 300 years ago," says team member Katsuji Koyama of Kyoto University. "The black hole was a million times brighter three centuries ago. It must have unleashed an incredibly powerful flare."

It takes light from the Milky Way Galaxy’s center about 26,000 years to reach Earth, so when astronomers observe the black hole and the gas cloud, they are actually seeing events that took place 26,000 years ago. At that time, Earth was still plunged in the last ice age, and humans were living in caves.

Astronomers don’t know why Sagittarius A* produced such a powerful flare three centuries ago. One possibility, says Koyama, is that a giant star exploded. The blast wave from the explosion plowed up gas and swept it into the black hole, leading to a temporary feeding frenzy that awoke the black hole from its slumber and produced the giant flare.

The Daily Galaxy via chandra.harvard.edu

Comments

THE MANY BLACK HOLES IN THE COSMOLOGY THEORIES

Quote 1: "A swarm of 10,000 or more black holes may be orbiting the Milky Way's super massive black hole . . .".

Ad: Accordingly to the standing theories, the larger hole should have absorbed all the minor ones. Where are the logics?

Quote 2: "These relatively small, stellar-mass black holes, along with neutron stars, appear to have migrated into the Galactic Center over the course of several billion years".

Ad: When combining "stellar-mass black holes" to the strange gravity models and to neutron stars, the cosmologists get it all very wrong.

Neutron stars are per definition neutral because they have no mass - and with no mass, they cannot possibly be connected to the strange and illogical mass-gravity theory, which again is connected to the also very strange theories of "black holes".

- The possibility of an opposite migration should be considered:

New stars are born in the centre of our galaxy. And the very shape of the Milky Way barred galaxy indicates that larger spheres of gas and matter are funneled OUT from the centre into the bars and abruptly in a 90 degree turn in the barred structure are moving further OUT in the galactic arms.

Quote 3: "As black holes orbit the center of the Galaxy at a distance of several light years, they pull on surrounding stars, which pull back on the black holes. The net effect is that black holes spiral inward, and the low-mass stars move out".

Ad: The general movement in the centre just shows a swirling structure in which everything are moving around on the vortex sides.

Stating that: "The net effect is that black holes spiral inward, and the low-mass stars move out" - is just illogical nonsense. The net effect is of course spiraling OUTWARDS and the stars and everything else are moving OUTWARDS.

The cosmologists are completely stuck in their strange gravity models which results in all kind of strange and contra dictionary statements.

There is NO pulling anywhere, only the very strong swirling centrifugal effect that results in the OUTWARDS moving stars. Just as my explanation states above.

- Nothing should be able to escape from the black holes they say, but here stars are leaving the so called black hole in spite of their strange gravity theories. Just as in my explanation states above.

When excludingly working with the illusive (and not excisting gravity force) in stead of using the known facts of the other 3 basic forces, the cosmologists NEVER will get it right.

All in all, this article mostly and formost reveals the many black holes in the minds of modern cosmologists and astrophysicists.

Ivar Nielsen
Natural Philosopher


Mr. Natural Philosopher, you just lost all credibility by saying that neutron stars have no mass. I stopped reading your rant after that nonsense.

yep, the crackpots and full-of-shite types seem to flock to the comments on this site to spew their garbage

@Agent Smith,

Would you like to explain yourself closer on this matter?

Ivar Nielsen
Natural Philosopher

"Neutron stars are per definition neutral because they have no mass..."

" Natural Philosopher "

... my brain hurts

Neutron stars are, in fact, extremely massive. They are almost as massive as the (ordinary) stars from which they are produced when they collapse in on themselves - a little of the mass of the original star is lost in a massive (very large and violent) explosion. A hint - just because a neutron is electically neutral, this does not mean it doesn't have a mass...

SHAME ON ME – OR NOT?

I´m sorry for confusing "neutron" for "neutrino" in my hurry to reply to this article.

It was the content in this quote that got me confused:

"The net effect is that black holes spiral inward, and the low-mass stars move out. From the estimated number of stars and black holes in the Galactic Center region, dynamical friction is expected to produce a dense swarm of 20,000 black holes within three light years of Sgr A*. A similar effect is at work for neutron stars, but to a lesser extent because they have a lower mass”.

- Here they talk of "low mass" stars that move out from the galactic centre, and:

"A similar effect is at work for neutron stars, but to a lesser extent because they have a lower mass".

- This is a severe contradiction if neutron stars really should be very heavy indeed, after a supposed supernova explosion collapse.

- Apparently the cosmologists themselves cannot agree if a neutron star have a lot of mass or not - so it´s very easy to be confused.

And maybe I´m right after all in my confusion? Are neutron stars heavy or not that heavy?

- I still don´t agree with the gravity-formation theories of neutron stars - or for that matter with the formation theories of our Solar System or of our galaxy.

Ivar Nielsen
Natural Philosopher

Ivar, Where do you come up with this stuff? You could host your own Republican rally with this spew.

@Q,
Thanks, but it would then be a Liberal rally . . .

Really, I´m just trying to get some logics out of the illogic spew that modern cosmologist pour out in our face.

Kindest Ivar

@Ivar

Have you ever considered reading a book on this subject? Just because something seems reasonable to you does not make it so. The death sequence of stars is well documented in many books on the subject. Or for that matter you can probably find the information on the net. In a nutshell: Dying stars produce white dwarfs - tiny stars packed the protons and neutrons. They weigh almost as much as the parent star but in a much smaller space. Bigger stars produce white dwarfs of much high mass. The higher mass causes the matter inside the dwarf to crush together into degenerate matter - which has no electrical charge. The stars, more massive than white dwarfs - are called neutron stars. They are likely much smaller in diameter than white dwarfs. Then stars even bigger than that result in white dwarfs that are even more massive, and they collapse into black holes.

White dwarfs = small and massive
Neutron stars = smaller and much more massive
Black holes = so massive that they collapse into a singularity, i.e. a dimensionless point.

I hope that this helps to clear up your confusion.All the best


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