Yes, I know it’s just barely over two weeks away from the Second American Tea Party. However, my mind needs a break. A brief distraction from the momentary glimpses of sheer panic and oppression that the image of The Messiah brings.
From Ars Technica (by far my favorite site on the web):
Supermassive black holes are often accompanied by two things: an accretion disk of matter in its death throws and a pair of relativistic jets that eject some of this matter in a last-minute pardon prior to its removal from the universe. While black holes are known for capturing every bit of matter or energy that gets too close, it has also been theorized that they will eventually stop growing. It is believed that these two phenomena—matter being devoured at the edge of the disk while being pushed away by the jets—form a sort of self-regulating system that keeps these monsters in check.
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Through these observations, the pair concludes that these emission lines originate in an accretion disk wind. For a wind to occur, some driving force must exist behind it, giving it a push. The obvious candidate in such a situation would be radiation pressure, but astrophysical calculations show that radiation pressure alone would to insufficient to impart enough momentum to drive this wind. The remaining push can, however, come from X-Ray heating and thermal pressure. Sample calculations confirm that a thermal driving force, assisted by radiation pressure, can successfully produce this mighty wind.
The researchers calculated that the wind is capable of carrying away approximately 10-8 solar masses worth of material each year. The rate at which the wind drives mass away from the black hole is interesting, because it is approximately the same rate of mass driven away via the relativistic jets. This is doubly interesting because it suggests that the black hole is able to maintain a balance of mass coming in and mass going out, regardless of the mechanism by which mass leaves the system—jet or wind.
The authors conclude by stating that these observations give “a strong indication that like their supermassive counterparts, stellar-mass black holes can regulate their accretion rate by feedback into their environments.” They also reiterate the importance of the finding that the high intensity of the radiation field from the disk is able to re-direct the accretion flow away from the relativistic jet, and into the outward bound wind: “our results point to fundamental new insights into the long-term disk-jet coupling around accreting black holes and hint at tantalizing evidence of the mechanism by which stellar-mass black holes regulate their own growth.” This reassures us that the equations that describe gravity do indeed work at the vastly different length and time scales that exist between stellar mass and supermassive black holes.
Yes, this does mean of course that we can’t “volunteer” Nancy Pelosi for the first manned space mission into a black hole. After all, do we really want her solar wind coming back?