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Monster Black Holes May Lurk All Around Us (yahoo.com)
Taco Cowboy quotes a report from Yahoo News: Astronomers have stumbled upon a supermassive black hole in an unexpected corner of the Universe, implying these galactic monsters are much more common than once thought, a study said Wednesday. The giant, with an estimated mass 17 billion times that of our Sun, was discovered in a relative desert, astronomers from the University of California, Berkeley, wrote in the journal Nature. "While finding a gigantic black hole in a massive galaxy in a crowded area of the Universe is to be expected -- like running across a skyscraper in Manhattan -- it seemed less likely they could be found in the Universe's small towns," said a university statement. Big, star-rich galaxies where supermassive black holes had previously been found, are very rare. Smaller ones like the NGC 1600 galaxy housing the newly-discovered whopper, are much more common, but were not previously thought to be appropriate host. "So the question now is: 'Is this the tip of an iceberg?'" said study co-author Chung-Pei Ma. "Maybe there are a lot more monster black holes out there that don't live in a skyscraper in Manhattan, but in a tall building somewhere in the Midwestern plains." The largest supermassive black hole spotted to date tipped the scales at about 21 billion solar masses, said the study authors.
That's quite not the case. The Dark Matter affects how galaxies rotate.The movement of the outer parts of a large galaxy are in a way as if the galaxy was much heavier than we would expect just from the radiation coming from that galaxy. So we already know that galaxies contain more (gravitationally detectable) matter than we see (elektromagnetically detectable), and that additional matter doesn't emit any light, hence we call it Dark Matter. A supermassive black hole in a small galaxy will not too much affect the rotation of a large galaxy nearby. Thus supermassive black holes in small galaxies won't explain the effects that forced us to postulate the existence of Dark Matter.
So neither supermassive black holes in the galaxy's center nor ejected supermassive black holes can explain the effect.
When will people stop thinking of black holes as giant vacuum cleaner? They're not. What they are is gigantic masses concentrated in a relatively small space creating big gravity. Other objects massive enough (i.e. stars) spin around them, exactly like planets spin around the sun but don't fall into it.
There is 0 evidence that what we call a "black hole" is an actual real class of objects that really exist.
Black holes is a prediction of our theory which matches observations so far. A recent example is the black hole merger causing the gravitational waves detected at LIGO.
Unless we find a different theory which matches observations better and which says that black holes are in fact not black holes but something else, we will think of these objects as black holes.
Theory suggests that black holes cannot form because they would require infinite time to collapse.
This is plain wrong. The collapse happens in a very short time, in the proper frame of reference.
See for example http://physics.stackexchange.c... for more details.
To calculate the time a celestial body needs to orbit a galaxy, you thus calculate it as if the whole mass inside the orbit was concentrated at the center of the galaxy, and you just ignore all mass that is outside of the orbit. Thus, the distance to the center and the rotational speed of any given star in a galaxy gives you an estimation of the mass of the galaxy until the star's orbit, if you know the mass of the star itself. If you do this for several stars at different orbits, you get an idea how the mass in the galaxy is distributed. Of course, this calculation is just a rough approximation, as you have to account for General Relativity effects for better results.
But still, this rough approximation already shows, that especially for the stars in the outer regions of a galaxy, the mass of the galaxy part within their orbit has to be about five times more heavy than what the estimation from the emitted light would indicate.
When will people stop thinking of black holes as giant vacuum cleaner? They're not. What they are is gigantic masses concentrated in a relatively small space creating big gravity. Other objects massive enough (i.e. stars) spin around them, exactly like planets spin around the sun but don't fall into it.
As the center of gravity gains mass, formerly stable orbits become unstable and the orbiting bodies fall into the gravity well. This can result in chain reaction which seemingly acts like a giant vacuum cleaner.
Other objects massive enough (i.e. stars) spin around them, exactly like planets spin around the sun but don't fall into it.
Orbits are not a function of mass, anything from an electron to a small black hole can orbit around a supermassive black hole and have the exact same orbit.
exactly like planets spin around the sun but don't fall into it
Except the proto-planets that did get sucked up in the Sun while our solar system was being formed.