Milky Way’s Black Hole Gave Off a Burst 300 Years Ago

by Fraser Cain on April 15, 2008

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Our Milky Way’s black hole is quiet – too quiet – some astronomers might say. But according to a team of Japanese astronomers, the supermassive black hole at the heart of our galaxy might be just as active as those in other galaxies, it’s just taking a little break. Their evidence? The echoes from a massive outburst that occurred 300 years ago.

The astronomers found evidence of the outburst using ESA’s XMM-Newton space telescope, as well as NASA and Japanese X-ray satellites. And it helps solve the mystery about why the Milky Way’s black hole is so quiet. Even though it contains 4 million times the mass of our Sun, it emits a fraction of the radiation coming from other galactic black holes.

“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 team gathered their observations from 1994 to 2005. They watched how clouds of gas near the central black hole brightened and dimmed in X-ray light as pulses of radiation swept past. These are echoes, visible long after the black hole has gone quiet again.

One large gas cloud is known as Sagittarius B2, and it’s located 300 light-years away from the central black hole. In other words, radiation reflecting off of Sagittarius B2 must have come from the black hole 300 years previously.

By watching the region for more than 10 years, the astronomers were able to watch an event wash across the cloud. Approximately 300 years ago, the black hole unleashed a flare that made it a million times brighter than it is today.

It’s hard to explain how the black hole could vary in its radiation output so greatly. It’s possible that a supernova in the region plowed gas and dust into the vicinity of the black hole. This led to a temporary feeding frenzy that awoke the black hole and produced the great flare.

Original Source: ESA News Release

About 

Fraser Cain is the publisher of Universe Today. He's also the co-host of Astronomy Cast with Dr. Pamela Gay.

Matthias April 15, 2008 at 12:35 PM

This might even explain the current quietness, I guess: if the outburst was violent enough, it may have cleared the hole’s neighbourhood of gas and dust.

Andy C April 15, 2008 at 3:10 PM

300 years ago? Wouldn’t it be more accurate to say 26,300 years ago?

pro April 15, 2008 at 3:25 PM

For us it is 300 years.
Adding the (uncertain) distance just confuses the issue.

DaveM April 16, 2008 at 4:39 AM

Perhaps all galaxies the size of the Milky way were highly active Quasars at the start of their life. The infant black hole at its hub feeding on nearby stars until the area immediately surrounding it lies relatively empty.

I wonder what the view from earth would be like if the milky way was a quasar galaxy?

John in Missouri April 16, 2008 at 6:40 AM

On the contrary, saying “300 years ago” for an object in the center of our galaxy very definitely did confuse me. I encourage future authors to qualify such statements to ensure that such confusion can be resolved. “Something like “evidence of a burst appeared three hundred years ago” would do the trick.

Peter K April 16, 2008 at 7:10 AM

John, doesn’t evidence…appeared 300 years ago, mean that it was Galileo’s protege doing the observation? More helpful would be to abolish “ago” and just say 300 years out from the centre of the galaxy (at c).

pradipta April 16, 2008 at 7:50 AM

Since the ancestral time, world space research is progressing on wrong concept because we unknown about space mirror which is a great mystery and creator of lots of mysteries viz. milk ways, galaxies, nebulas, supernovas, white dwarfs, black holes etcs. Hence without study of space mirror the space research has no future.

It can not explain in short. Therefore it invites to visit http://www.spacemirrormystery.com to know the logic and original truth.

Mirror reflects frontier. Mirror functions like a wall. There is nothing ahead of mirror but reflection makes lively atmosphere into mirror. If two mirrors face each other in parallel position the concerned area between mirrors is converted to a biggest atmosphere because the concerned area reflected unlimitedly as front side and backside into each mirror frequently. Space mirror is based on above rule and we are unknown about space mirror. From sun the objects of area 225 million kilometer to 300 million kilometer of solar system reflects unlimitedly, we find a very deep space and through giant telescopes we watch mystery after mystery. Telescope enlarges view not closes near view. Following may clear the concept “A visitor of a desert often find mirage. If he moves mirage also moves. He can never reach near the mirage. If he tries he can see enlarge view of mirage as smoky atmosphere through a telescopic instrument”.

Giant telescope like Hubble and others may be the milestone of our technology but it can not help the real space research.

pro April 16, 2008 at 10:55 PM

The point is, if Galileo’s protege actually was observing (with the right means to do the observation, because I think this event was visible only in IR), he/she would actually see the outburst.
So for us, the event happened 300 years ago and what we are seeing now are the echoes of it, reflections of the blast from interstellar stuff that is 300 ly away from our galactic BH. This distance is known to much better precision than our distance from the centre of the MW. …
There should not be any confusion for anyone….

Joe M. August 26, 2008 at 4:13 AM

Well, at least we don’t have to worry that we will get a GRB?

anonim September 12, 2008 at 1:22 AM

First I don’t believe black holes exist!

They assume that in every center of a galaxy must exist a black hole. After that they start searching for some patterns they believe a black hole must have and if they found some of that patterns they say “look, we have a black holes”.

This is not science, this is crazy.

What about plasma in a universe? Why they don’t say nothing about it?

They are not capable of fully understand our closest “black hole”, Sun, but they are sure about what they saw at a very high distance.
For example they can’t explain why the temperature inside the sun (measured in sun spots) is lower than in sun’s corona. Because, according to main stream sun model, inside the sun are thermonuclear reactions …

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