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.

Comments

Re:Maybe this is the "missing mass"?

[Sique]

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.

Re:Maybe this is the "missing mass"?

[Sique]

They have to be within the galaxies to explain their movement. The outer parts of a galaxy rotate with a speed that is only explainable if the part of the galaxy that is within the orbit of the outer parts is much heavier than just the mass we can detect by the emitted light. And it has to be distributed througout the galaxy as the effect is larger, if we go more far away from the center.

So neither supermassive black holes in the galaxy's center nor ejected supermassive black holes can explain the effect.

Re:Black hole in the astronomical desert

[Anonymous Coward]

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.

Re:Maybe this is the "missing mass"?

[Sique]

You don't need to simulate all bodies in a galaxy to determine an orbit close enough to see some aberrations. For simple calculations, you could just imagine all mass within an orbit to be concentrated in the central point of that orbit, the gravitational center. Isaac Newton already proved that every homogenous hollow sphere has the same gravitational properties to a body outside the sphere as if all mass of that hollow sphere was concentrated in the gravitational center. The gravitational effect of a homogenous hollow sphere to a body inside of it on the other hand is zero.

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.