Astronomers Find Gas Cloud About To Fall Into Black Hole

First time accepted submitter pigrabbitbear writes "Black holes are basically celestial Cookie Monsters, gobbling anything and everything in sight. But because that appetite includes light itself, it's incredibly rare for us to actually see a black hole suck back an interstellar treat. Astronomers using the European Southern Observatory's Very Large Telescope have found just that: a mysterious, giant gas cloud that's rapidly been pulled into the maw of a supermassive black hole. The researchers, led by Reinhard Genzel of the Max-Planck Institute for Extraterrestrial Physics in Germany, discovered the cloud as part of a now 20-year ESO program tasked with tracking stars as they whirl around the supermassive black hole, known as Sgr A*, at the center of our galaxy."

Comments

What an honour.

[bejiitas_wrath]

To see this cosmic event happening before our eyes. I know that it has already happened and we are seeing the light from the event finally reaching our eyes or CCDS, but this is an awesome event to watch and shows how incredible the universe around us truly is.

It is humbling to think that it could be our solar system spiraling into the black hole, but we could save Earth if we had 6*6*6 levels of energy, we could keep Earth poised next to the black hole and watch everything else fall in. Until the Doctor opens the Satan pit that is...

Black Holes aren't hard to see because the suck up

[MichaelCrawford]

... light. They are hard to see because there aren't very many of them.

They are the residue left over by the death and subsequent collapse of particularly massive stars. Such stars can take other courses during their death throes, such as ejecting their mass all over the neighborhood in a supernova.

It is thought that at the center of our own galaxy and many other galaxies there are black holes that are the result of the particularly plentiful gas and dust there, but they are hard to see because they are surrounded by more of that gas and dust.

While we cannot see what is inside the event horizon of a black hole, we certainly can see what is just outside the even horizon. It's not just that there is an incredibly strong gravitational field there, but the gradient of that field is quite steep, that is, as one gets ever closer to the event horizon, the field gets increasingly stronger quite quickly.

The result is that any particle bound states such as atoms, molecules, atomic nuclei, or even nucleons such as neutrons and protons are torn apart because the particles that are closer to the event horizon are accellerated inward much faster than the more distant particles, despite the distance between all of the particles in that bound state being no more than the distance of an electron from the proton in a Hydrogen atom.

The result of all that tearing apart of bound particles, as well as the particles colliding with each other, charged particles interacting with the magnetic fields of rotating black holes and so on, is that the region just outside of the even horizon emits particularly intense, high energy, short wavelength X-Rays.

Those X-Rays are so bright that we can see them, if I understand correctly, being emitted from the material falling into black holes located in other galaxies.

I'm not really a software engineer; I only play one on the Internet. But I really am an astronomer.

"Cookie Monsters"

[Baloroth]

Really Slashdot? "Cookie Monsters"? "Interstellar treat"? Wow, I think I may have found a new low for a Slashdot summary.

Well, until tomorrow, anyways.

Re:Black Holes aren't hard to see because the suck

[Baloroth]

Wouldn't that mean black holes aren't necessarily rare, but only that black holes near gas clouds are rare? There could be millions of them in the interstellar void, but with no gas to form an accretion disk, they would be completely invisible. And lensing effects would be incredibly difficult to detect. In fact, I thought that we only really detected most black holes if they were part of a binary system (which gives plenty of matter for x-ray radiation).

And, of course, it is absolutely impossible to see something that emits no radiation (ignoring the possibility of Hawking radiation, which is too weak to see in most cases anyways), so technically black holes aren't hard to see: they are impossible to see. We can only infer it's presence through the effect it has on matter outside the black hole itself. The x-ray radiation is not technically from the black hole itself, but rather from the effect that it's gravitational field has on incoming matter.

I'm not an astrophysicist... but I'm working on changing that.

They know it's about to be pulled in?

[93 Escort Wagon]

So did these hot-shot researchers even consider warning the gas cloud? No, they just plan to sit back and watch it happen, the bastards!

Re:When?

[rrohbeck]

So what does "about to" mean in astronomical terms? Tomorrow? Next year? In a few million years?

Roughly two years: http://www.scientificamerican.com/article.cfm?id=black-hole-gas-blob

I expect that you are correct, however...

[MichaelCrawford]

... because most black holes are formed from the remains of particularly large stars, and such stars are formed from the gravitational collapse of large gas and dust clouds, one would expect most black holes to be close to regions where lots of stellar formation has taken place. Such places would quite likely still have lots of gas around.

However a black hole could have formed early in the history of the Universe. It is thought that if there are any really small black holes, they are left over from the Big Bang. Those black holes could indeed be in places where we could not detect them, and because they are not very massive, we could not see their effects on nearby matter.

It is the very small black holes that emit lots of Hawking radiation. The intensity of it increases with the gradient of the gravitational field. Large block holes have a less steep gradiant, smaller holes a steeper one. Very small black holes may have formed early in the history of the Universe, but by now would have evaporated due to emitting all that Hawking radiation.

Two black holes colliding would be quite cool

[MichaelCrawford]

Because if they did, quite likely they would emit some gravitational waves that we might be able to detect with optical interferometers here on earth.

Einstein's general relativity predicts such waves theoretically, but because gravity is such a weak force - consider that an object with the mass of the earth is required to make you feel your own mass bearing down on the soles of your feet - even the gravitational waves emitted by the objects in our own solar system are too weak to detect.

Gravitational waves are only emitted from asymmetric motions of large amounts of mass. The explosion of a supernova, while not perfectly symmetric, is close enough to symmetric that it doesn't emit detectable waves.

I would expect that two black holes orbiting close to each other at very high radial velocity, or just two very massive stars, would emit waves we would eventually be able to detect here on earth.

We have yet to find any exceptions to the theoretical predictions of Einstein's theory of general relativity, but there are a number of things that it predicts that we are as yet technologically unable to confirm either through experiment or astronomical observation.

A few years ago, someone measured the speed of gravity by observing the effect of Jupiter's gravitational field on the apparent position of a bright radio source, but their precision was so poor that if the speed of gravity is significantly different than the speed of light, their measurement was unable to distinguish it.

Re:Black Holes aren't hard to see because the suck

[oxdas]

I seem to remember back in my university days (its been a little while) studying that their was an inverse relationship between the size of a black hole the temporal and gravitational effects at the event horizon. In effect, if the black hole was massive enough (million of stars), it could be theoretically possible to cross the event horizon with my atomic structure intact. I always imagined what a fate it would be to fall into such a monster and watch eternity pass before my eyes. I am not an astronomer, however, so my memory on this matter could be faulty.

Life would not be possible near a black hole

[MichaelCrawford]

But I don't expect that many black holes would be big enough as to irradiate an entire galaxy to the point that life is impossible anywhere in that galaxy.

However, the very brightest celestial objects that we can see are the Quasars, or Quasi-Stellar objects. They are "Stellar" in that they appear to be pinpoint light sources, but their spectrum is heavily weighted to the bluer, higher energy end of the spectrum, and if I understand correctly do not appear to be radiating light as a result of just being hot. When an object emits thermal radiation, while that radiation is blueer (or 'X-ray-er') if it is particularly hot, the shape of the spectral intensity distribution takes an easily calculated form called the Planck Distribution.

There are lots of other ways to generate blue light other than thermally, but for many years, the incredible power of the Quasars was a mystery. The red shift of their spectrum that results from the expansion of the Universe between us and them is quite large, so clearly they are the farthest objects we can see, as well as the oldest, and must have formed not long after the beginning of the Universe.

It is thought now that the Quasars are very large black holes, such as those at the centers of some galaxies such as our own, but much much larger. I expect life would not be possible anywhere in their vicinity.

If a supernova goes off in any nearby galaxy, we can easily resolve it from its neighboring stars with average sized astronomical telescopes. Supernovas in more distant galaxies cannot be resolved, but they are at times as bright as the entire galaxy that they are contained within. If a supernova goes off within our own galaxy, at times we can easily see it at high noon on a bright, sunny day.

If any of our nearby celestial neighbors were to go off in a supernova, we would only get the bad news when all life on earth was wiped out almost instantly. We wouldn't just get 73h c4nc3r and die a few years later; the Earth's entire atmosphere would be blasted off into interstellar space.

The abundance of heavy elements not just on earth but throughout our solar systems makes us certain that the Sun is a second generation star, whose first generation star went off in a supernova, the intense pressure, heat and particle energy of which formed all those heavy elements that we find so useful for things like hard drive platters and Liquid Crystal Displays.

Re:Black Holes aren't hard to see because the suck

[AlanS2002]

Wouldn't that mean black holes aren't necessarily rare, but only that black holes near gas clouds are rare? There could be millions of them in the interstellar void, but with no gas to form an accretion disk, they would be completely invisible. And lensing effects would be incredibly difficult to detect. In fact, I thought that we only really detected most black holes if they were part of a binary system (which gives plenty of matter for x-ray radiation).

And, of course, it is absolutely impossible to see something that emits no radiation (ignoring the possibility of Hawking radiation, which is too weak to see in most cases anyways), so technically black holes aren't hard to see: they are impossible to see. We can only infer it's presence through the effect it has on matter outside the black hole itself. The x-ray radiation is not technically from the black hole itself, but rather from the effect that it's gravitational field has on incoming matter.

I'm not an astrophysicist... but I'm working on changing that.

This is similar to one alternate theory to the whole dark matter garbage, to explain the amount of mass thought to exist in the universe (most of which we can't account for). Except instead of millions this theory suggests billions of tiny (about the size of a small town) black holes.