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Supermassive Black Holes Can Abort Star Formation

Posted by Soulskill on from the glad-our-galaxy-is-pro-life dept.

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."

7 of 67 comments (clear)

  1. Will this radiation sweep over the rim by CRCulver · · Score: 4, Interesting

    "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.

    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?

  2. Good Slashdot post by mbone · · Score: 4, Interesting

    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.

    1. Re:Good Slashdot post by painandgreed · · Score: 3, Interesting

      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 cessation of star-making is pretty much the same as the cessation of life. Without stars there will be no supernovas. Without supernovas, there will be no elements higher than the occasional helium atom. Unless we come up with a way to make a life form out of pure hydrogen, the lack of stars pretty much means the lack of life.

    2. Re:Good Slashdot post by icegreentea · · Score: 2, Interesting

      It means that life that already started may not cease when supermassive black holes enter the super radiant (ha!) phase. The article mentions this phase lasts hundreds of millions of years. The estimated time of start of life on earth is like 4 billion years ago. So if the atmosphere of a life bearing planet can shield enough of the xrays, then life could well continue on a planet during the super radiant stage.

      It just means life (well, really stars) will end faster in those galaxies in the LONNGGG run.

    3. Re:Good Slashdot post by mbone · · Score: 2, Interesting

      So if the atmosphere of a life bearing planet can shield enough of the xrays, then life could well continue on a planet during the super radiant stage.

      Exactly. Or, even if not, life could reform.

      Given the number of galaxies that the Milky Way has eaten (which would restock the missing gas), and the "missing" 500 million years or so of life in the very early history of our planet, I would not be too shocked if this had happened to the Milky Way a while ago, say 4.3 to 4.2 billion years ago. Of course, there is no evidence of this.

      If this happened now, some life on Earth, such as bacteria buried kilometers down in the crust, would almost certainly survive it. As for us, well, there might be a mine-shelter gap...

  3. Re:Interesting... by painandgreed · · Score: 2, Interesting

    Are there any conflicts with the Einstein Field Equations as this would suggest?

    Doubtful, however this probably would allow for some guess at bounding values for several parts of the Drake Equation values*. Not only for star formation but the lack of star formation would mean less high elements which would mean less planets capable of supporting life (ie rocky planets). The lack of supernova also influences later star formation IIRC as the supernova shockwaves help jump start the next generation of star formation as well as provide elements higher than helium.

    *ya, ya, the Drake Equation is for our galaxy but we can apply it to other galaxies also.

  4. Re:What are these galaxies made of if not stars? by mbone · · Score: 3, Interesting

    What sort of timescale are we looking at for such a galaxy to exhaust it's stars and become invisible to us?

    Depends, but almost certainly >> the age of the Milky Way. After all, we have a bunch of globular clusters orbiting the galaxy, with no gas and all old stars, which are certainly still visible.