Everything But Light?
August 25, 2011 11:41 AM Subscribe
Looking at star Swift J1644+57 being eaten by a black hole, NASA animation shows jets of energy shooting out. I thought nothing could escape a black hole, not any form of energy . So how and where are the relativistic bursts of gamma and xrays going
Imagine a figure skater doing a pirouette, spinning faster and faster and faster, until she can no longer hold her arms in.
posted by Blazecock Pileon at 11:48 AM on August 25, 2011
posted by Blazecock Pileon at 11:48 AM on August 25, 2011
Best answer: The Stuff that you're seeing isn't escaping from within the event horizon, which is what we mean by "nothing escapes a black hole." It's escaping from really close to the event horizon. Sort of like if the entire city of Cincinatti fell into a pit, and we learned about it because we saw a huge swarm of people from the suburbs running away from it; it's not that anybody survived the Giant Random Pit in Ohio, but those who were just far enough away to not fall in, were able to get away.
posted by Tomorrowful at 11:48 AM on August 25, 2011 [9 favorites]
posted by Tomorrowful at 11:48 AM on August 25, 2011 [9 favorites]
As blue_beetle says, the event horizon is the border of the black hole. Once matter or energy crosses the event horizon, it cannot escape, because the escape speed is greater than the speed of light.
However, as a star falls into a black hole, it is torn apart by the black hole's gravity, and the resulting plasma can be swept up in the magnetic field of the black hole. This results (though a process that is not entirely understood) in jets of extremely hot plasma shooting out at the magnetic poles of the black hole. Because the plasma hasn't fallen into the black hole, and the escape speed outside the event horizon is less than the speed of light, the jets (which are actually moving near the speed of light!) can escape.
The plasma in the jets and the infalling plasma, emit the gamma and x-ray radiation that we observe with Swift.
posted by BrashTech at 11:52 AM on August 25, 2011
However, as a star falls into a black hole, it is torn apart by the black hole's gravity, and the resulting plasma can be swept up in the magnetic field of the black hole. This results (though a process that is not entirely understood) in jets of extremely hot plasma shooting out at the magnetic poles of the black hole. Because the plasma hasn't fallen into the black hole, and the escape speed outside the event horizon is less than the speed of light, the jets (which are actually moving near the speed of light!) can escape.
The plasma in the jets and the infalling plasma, emit the gamma and x-ray radiation that we observe with Swift.
posted by BrashTech at 11:52 AM on August 25, 2011
This is the animation in question.
posted by exhilaration at 11:52 AM on August 25, 2011 [2 favorites]
posted by exhilaration at 11:52 AM on August 25, 2011 [2 favorites]
FWIW - One of Stephen Hawking's greatest contributions to the field was in the concept of Hawking Radiation which maintains that things do indeed escape from inside the event horizon due to quantum tunneling of the contents inside.
But all the posters telling you that the jets come from effects arising from outside the event horizon are , of course, correct.
posted by Poet_Lariat at 12:27 PM on August 25, 2011
But all the posters telling you that the jets come from effects arising from outside the event horizon are , of course, correct.
posted by Poet_Lariat at 12:27 PM on August 25, 2011
No, the particles in Hawking radiation that escape do so from just outside the event horizon. Or at least they are hypothesized to do so: The process isn't exactly well understood at this point in time since we don't have a quantum theory of gravity.
The jets emitted by matter falling into a black hole are a well known phenomenon. The largest examples are probably those emitted by quasars, which are incredibly powerful.
posted by pharm at 2:50 PM on August 25, 2011
The jets emitted by matter falling into a black hole are a well known phenomenon. The largest examples are probably those emitted by quasars, which are incredibly powerful.
posted by pharm at 2:50 PM on August 25, 2011
Hawking radiation is far too dim to detect. Its only observable consequence is making black holes get smaller with time. (And a for a stellar mass black hole, it takes a very long time indeed for its size to change appreciably.)
posted by BrashTech at 7:15 PM on August 25, 2011
posted by BrashTech at 7:15 PM on August 25, 2011
Not to derail, but why is the light escaping the event horizon disc shaped? I imagine black holes to be a point with an effect in the shape of a sphere. The disc shape makes me think of a sink drain which would be almost (??) 2 dimensional?
posted by kookywon at 2:14 PM on August 26, 2011
posted by kookywon at 2:14 PM on August 26, 2011
Black holes are shaped like planets (spherical), but aren't zero dimensional. Stuff orbits them like stuff orbits a planet. They tend towards discs.
posted by blue_beetle at 3:01 PM on August 26, 2011
posted by blue_beetle at 3:01 PM on August 26, 2011
Assume they're basically planets, just smaller (and more massive). Gravity decreases at the square of the distance, meaning stable orbits are quite possible. It also means you can do things like gravitational slingshots, which in some cases will propel matter away from the black-hole at high speed without any other propulsion.
posted by blue_beetle at 3:04 PM on August 26, 2011
posted by blue_beetle at 3:04 PM on August 26, 2011
Also (almost forgot), like most stellar objects, black holes spin (aka rotate) meaning there would be an equator, where discs of matter tend to form.
posted by blue_beetle at 3:06 PM on August 26, 2011
posted by blue_beetle at 3:06 PM on August 26, 2011
This thread is closed to new comments.
posted by blue_beetle at 11:41 AM on August 25, 2011 [1 favorite]