Black Hole, maybe?

[rigney]

Is there any real proof that black holes exist other than as axial points of galaxies?

[Nano]

Einsteins GR predicted them, and that theory has been verified a lot of times.

 

"Real proof" of a BH is a bit tricky since they hardly emit radiation. Maybe somebody else can fill me in whether Hawkins theory of escaping particles from the edge of the event horizon could one day be detected and linked to being emmited from a black hole?

 

The way astronomers detect them today is through gravity. When a BH passes our vision of a distant star, it will bend the light from all directions around it, making it look like several similar stars here from earth, when in fact there is only one.

[AlexandruLazar]

There are several detection methods in fact. The one you have pointed out is one; another common one is when you see that an interstellar gas cloud is happily and uneventfully gliding along, and then all of the sudden it stumbles upon something that attracts gas and dust with so much force that it compresses it to the point where it actually starts radiating far high in the X radiation spectrum. There are some oddballs, too; for instance, you see stars orbiting what should be a pair in a binary system, there is a clear radiation in the X radiation spectrum (due to gas being drawn from the other star), but you cannot trace it back to a companion object and the orbital parameters cannot be those of some other object (like a neutron star).

 

Really massive black holes have been thought to be located in some galactic nuclei only after black holes have been seen in other places.

[rigney]

Then they don't necessarily have to be the axis of a galaxy or a quasar? I'll read on it!

[Moontanman]

Stars in the middle of our galaxy can be shown moving so fast a movie of their movements has been made. they are moving too fast to be in orbit around anything but a black hole.

 

Stellar mass black holes have been detected by gravity lensing and by their effects on other objects. Theory suggests black holes should be fairly common.

 

I am pretty sure a quasar and a galaxy are the same thing, a quasar is a galaxy that has an actively feeding black hole and what we consider a normal Galaxy doesn't.

[Airbrush]

Interesting question about evidence for stellar black holes. There is enough to convince Stephen Hawking.

 

"In June 1990 Stephen Hawking conceeded a bet (made in 1974) with Kip Thorne. He agreed that the Cygnus X-1 system contained a black hole. For over 200 years since John Michell described "dark stars" (stars massive enough to stop even light escaping from their surfaces), and Einstein's General Theory of Relativity predicted them, black holes had been an astronomical enigma. However, even since Hawking conceeded the bet the inability to directly observe black holes left some astronomers still unconvinced. Slowly the case for the existence of black holes has been built by indirect observational evidence."

 

I thought they had observed binaries with an invisible partner. The only way to explain the visible star's movement is the gravity from a black hole. The motion of stars in the center of our Milky Way around Saggitarius A could only be an object of millions of solar masses to cause the stars to move that fast and in such small orbits.

 

"An enormous X-ray burst in the centre of the galaxy RX J1242-11 has been observed with the Chandra and XMM-Newton X-ray telescopes by an international team of astronomers. This outburst, one of the most extreme ever detected in a galaxy, was most likely caused by gas from a destroyed star that was heated to millions of degrees Celsius before being swallowed by a centrally located supermassive black hole. The energy liberated in the process was equivalent to a supernova explosion.

 

"Now, with all the data in hand, we have the smoking gun proof that this spectacular event has occurred," said coauthor Gunther Hasinger, of Max Planck Institute for Extraterrestrial Physics (MPE).

 

The black hole in the centre of the galaxy RX J1242-11 is estimated to have a mass of about 100 million solar masses. The astronomers believe about one percent of the star's mass was accreted, by the black hole. This small amount is consistent with predictions that the momentum and energy of the accretion process will cause most of the destroyed star's gas to be flung away from the black hole. "

 

http://astronomy.swin.edu.au/sao/astronomynews/astronews2004s1.xml

[Mr Skeptic]

Maybe somebody else can fill me in whether Hawkins theory of escaping particles from the edge of the event horizon could one day be detected and linked to being emmited from a black hole?

 

If by "one day" you mean "billions of years from now when the universe cools to the point where stellar sized black holes are warmer than the background radiation" then sure. Alternately, micro black holes are much hotter and those could be detected via Hawking radiation if we were to find one.

[Nano]

If by "one day" you mean "billions of years from now when the universe cools to the point where stellar sized black holes are warmer than the background radiation" then sure. Alternately, micro black holes are much hotter and those could be detected via Hawking radiation if we were to find one.

 

Remember that it is possible in theory to travel great distances in short time. If technology finds a way to exploit worm-holes, we might get much closer to a black hole. The radiation might also find it's way to us through worm holes.

[Mr Skeptic]

Remember that it is possible in theory to travel great distances in short time. If technology finds a way to exploit worm-holes, we might get much closer to a black hole. The radiation might also find it's way to us through worm holes.

 

But how would we tell the difference between a black hole and something that is simply really close to absolute zero?

[Nano]

But how would we tell the difference between a black hole and something that is simply really close to absolute zero?

 

I don't know, and that was also the reason why I said that someone else have fill me in (check the post) whether it is possible to distinguish it from radiaion emitted from elsewhere than a BH.. aarg.

 

Thanks for filling in