Milky Way Black Hole Could Reignite 117
sciencehabit sends us to Sciencemag.org for an account of a survey of nearby galaxies that points to the possibility that once-quiescent galactic nuclei could wake up and become active again. If the Milky Way's dormant black hole should become active, it could be bad news for life on Earth (and elsewhere in the neighborhood). The paper (PDF) is up on the arXiv.
Eye muss bee knew hear (Score:4, Informative)
I don't think we have anything to worry about. Nothing to see here (and if it happened, nobody to see it)
Re:Eye muss bee knew hear (Score:5, Informative)
That's not what the article says:
It's not understood what is causing the black holes to become newly active, because in most cases there is no evidence of collisions or mergers.
No evidence for "re-ignition" (Score:4, Informative)
Re:Axis of Rotation (Score:2, Informative)
Re:20 to 40%? Reignite? (Score:4, Informative)
Haven't you watched CSI: Stellar Cartography Unit?
Feed Me (Score:4, Informative)
Our galaxy's black hole, Sagittarius-A, is not considered active, although it does have some weak emissions, primarily at harmless infrared and radio wavelengths consistent with a very small accretion disc. The nearest star to the black hole is estimated to be about 70 times as far away from it as it would need to be for the gravitational forces to remove significant amounts of material from the star. It also has an orbital period of 15 years, so it would take a long time and a significant perturbance to fall significantly close. It doesn't seem likely at all that it would become active in the foreseeable future.
Re:Still not getting it ... (Score:3, Informative)
Quasars are an effect created by the supermassive black holes at the centre of each galaxy, these black holes consume tremendous amounts of mater (something like 10 sun masses a year) the more solar masses they consume the brighter they are. Obviously there is only so much material than can be pulled in by the supermassive black hole, eventually all the material is either ejected as high intensity engery (the quaser pulses we can observe) or consumed by the black hole.
The article mentions that astronomers have discovered galaxies with quasars which are old enough that the matter orbiting the black hole should have been used up. The current scientific hypothisis for old galaxies with quasars, is that the collision of two galaxies can generate new material which is pulled in by the supermassive black hole (thus supplying the matter to generate a quasar.) These older galaxies don't show any signs of recent collision and so the question of how the black holes in the centre are getting enough matter to generate a quasar needs to be asked. Since scientists don't know why there are quasars on these older galaxies they seem to be assuming that something else is causing new matter to be sucked into a galaxies supermassive black hole. The articles twist is this could potentially happen in our own galaxy, potentially killing us all.
Re:Eye muss bee knew hear (Score:3, Informative)
I don't think we have anything to worry about. Nothing to see here (and if it happened, nobody to see it)
While we are well out from the center, we'd be in periods of more danger from the radiation than those stars native to this galaxy, due to our cyclic motion going outside the galactic plane. More danger, yes, but whether the danger is significant and whether other side effects might dampen the effects, are factors not addressed.
In any case, reignition of an active galactic core is due to an increase in infalling matter, and that's obviously not necessarily due to galactic collision. We can't see the details of the matter near the core, so we can't tell whether there's clumps that can fall in en mass, or whether it's relatively smooth and unlikely to cause bursts of activity.