Slashdot Mirror
Supermassive Black Holes Can Abort Star Formation
cremeglace writes "Astrophysicists have found that when a supermassive black hole quickly devours gas and dust, it can generate enough radiation to abort all the embryonic stars in the surrounding galaxy. It's not clear what this means for life's ability to take hold in such a bleak environment, but the research shows that the process might have determined the fates of many of the large galaxies in the universe."
This reminds me of Larry Niven's short story "At the Core" (collected in Crashlander ) where an expedition to the galactic core finds that the density of stars in the area causes a chain of supernovas, whose radiation will eventually sweep over the outskirts of the galaxy and destroy life on Earth. Now that galactic cores are somewhat better understood, what's the current idea of how our neighbourhood could be affected by events in the center?
How long before Palin comes out against this? I am guessing it would go a little something like: 'Now the 'liberal elites' want us to think that God performs abortions?!'. Then she will follow up with various sentence fragments taken from a 'quote of the day' calendar.
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As if we needed any more proof that black holes suck.
I've abandoned my search for truth; now I'm just looking for some useful delusions.
For once, the Slashdot post is better than the original article.
The cessation of star-making is not the same as the cessation of life. It might be good for life. It might be bad. All we really know right now is that this has not happened to the Milky Way galaxy, so we have a sample of one where it did not occur.
The other thing missing in the original article is that galaxies are active things, and can and frequently do "eat" other galaxies - which brings new gas into the galaxy, and thus could restart star making (or make the black hole active again, or both).
Here is an astrophysics prediction : this galaxies will have a high Mass to Light ratio, since gas and dust will be expelled, but not dark matter.
What are these galaxies made of if not stars?
Gas, lots and lots of gas.
It's actually what stars are made of, along with the vast majority of planets. When stars super-nova, then they create dust, which can then become earth-like rocky planets. In baby galaxies and in galaxies with an active super-massive black hole, gas is being sucked in to the black hole so fast that it glows, It's like an ultra-massive star with a super-massive black hole core. The radiation from these black holes comes from the gas surrounding it falling in, not from the black hole itself. This radiation can potentially kick start other stars further out to form.
Basically what the article is saying, is that a black hole can become so large, that if it activates again (new gas is introduced in some way, or it has simply had so much to consume that if finally hit the right size) that it can kill any young stars in the galaxy. That doesn't mean the older stars will be eliminated, because once a star reaches a certain size its own pressure maintains the reaction without external influence. It's the ones that are still collecting gas and are too small to maintain their own reaction that can be snuffed out.
Furthermore, the gravity of a black hole, even a supermassive, has limits. Our solar system, for example, is well outside the range of the Milky Way's supermassive black hole - we are held in orbit by proximity to the mass of stars further from the center of the galaxy. So what you will end up with is not giant, invisible galaxies, but galaxies with a giant hole in the middle (like all galaxies with a non-active supermassive) and zero new star formation. It would take close to the heat death of the universe for them to become dark, and most galaxies will be nearly dark by then anyway.
Security is mostly a superstition... Avoiding danger is no safer in the long run than outright exposure. - Helen Keller
They are, but life typically forms around second or third gen stars. Before then, most of the matter in a galaxy is hyrdogen with a little helium thrown in. Only after a big round of massive stars + the associated supernovas do you start getting heavy elements in the proceeding star systems.
The upside though is that according to the article, only 33% of the galaxies observed displayed this phenomenon. That's still a massive (the majority) number of galaxies that are just fine. Most importantly including our own. If we EVER achieve interstellar travel that'll be great, but interGALACTIC travel is almost certainly never going to happen (hell, even in Star Trek's far out there perfect future intergalactic travel is not feasible), so it doesn't really matter that much to us aside from scientific knowledge. Our galaxy is one of the good ones. Besides, the majority of galaxies appear to be dwarf galaxies, which would be unaffected by this.
"People who think they know everything are very annoying to those of us who do."-Mark Twain