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A Strange Black Hole Is Shooting Out Wobbly Jets Because It's Dragging Spacetime:
Some 7,800 light-years away, in the constellation of Cygnus, lies a most peculiar black hole. It's called V404 Cygni, and in 2015, telescopes around the world stared in wonder as it woke from dormancy to devour material from a star over the course of a week.
That one event provided such a wealth of information that astronomers are still analysing it. And they have just discovered an amazing occurrence: relativistic jets wobbling so fast their change in direction can be seen in mere minutes.
[...] V404 Cygni is a binary microquasar system consisting of a black hole about nine times the mass of the Sun and a companion star, an early red giant slightly smaller than the Sun.
The black hole is slowly devouring the red giant; the material siphoned away from the star is orbiting the black hole in the form of an accretion disc, a bit like water circling a drain. The closest regions of the disc are incredibly dense and hot, and extremely radiant; and, as the black hole feeds, it shoots out powerful jets of plasma, presumably from its poles.
[...] "We think the disc of material and the black hole are misaligned," [astrophysicist James] Miller-Jones said. "This appears to be causing the inner part of the disc to wobble like a spinning top and fire jets out in different directions as it changes orientation."
[...] It's a bit like a spinning top that starts to wobble as it's slowing down, the researchers said. This change in the rotational axis of a spinning body is called precession. In this particular instance, we have a handy explanation for it courtesy of Albert Einstein.
In his theory of general relativity, Einstein predicted an effect called frame-dragging. As it spins, a rotating black hole's gravitational field is so intense that it essentially drags spacetime with it. (This is one of the effects scientists hoped to observe when they took a picture of PÅwehi.)
In the case of V404 Cygni, the accretion disc is about 10 million kilometres (6.2 million miles) across. The misalignment of the black hole's rotational axis with the accretion disc has warped the inner few thousand kilometres of said disc.
The frame-dragging effect then pulls the warped part of the disc along with the black hole's rotation, which sends the jet careening off in all directions. In addition, that inner section of the accretion disc is puffed up like a solid doughnut that also precesses.
"This is the only mechanism we can think of that can explain the rapid precession we see in V404 Cygni," Miller-Jones said.
[...] the team had to [take] 103 separate images with exposure times of just 70 seconds and [stitch] them together to create a movie - and sure enough, there were the wibbly wobbly spacetimey jets.
A video explaining the activity is available on Vimeo.
A rapidly changing jet orientation in the stellar-mass black-hole system V404 Cygni, Nature (DOI: doi:10.1038/s41586-019-1152-0)
(Score: 2) by DannyB on Thursday January 02 2020, @10:02PM (4 children)
Like complaining about a photo of a missing bunny rabbit. All I can see in the photo is the empty cage. No rabbit. So is it actually a photo of a missing bunny rabbit? Or actually a photo of a black hole?
The people who rely on government handouts and refuse to work should be kicked out of congress.
(Score: 2) by RS3 on Thursday January 02 2020, @11:03PM (3 children)
(Twilight Zone music playing in background...)
(Score: 2) by DannyB on Friday January 03 2020, @02:35PM (2 children)
I'm not sure if you missed the basic idea. A photo of an empty rabbit cage with an open door could be interpreted as, or described as, a photo of a missing bunny.
A photo of a big empty black spot that sent no photons to particular pixels in the image censor could be described as a photo of a black hole.
The people who rely on government handouts and refuse to work should be kicked out of congress.
(Score: 2) by FatPhil on Friday January 03 2020, @08:35PM
In other news - fortune tellers worldwide lose their crystal balls, when they become no longer able to see them.
In other news, we never saw any things anwyway, all we saw was photons now disconnected from the thing glitching a sensor inside our skulls.
In other news, epistemic and ontological philosophy are mostly tedious wank.
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 2) by maxwell demon on Saturday January 04 2020, @07:39AM
The difference between the open cage and the black hole is that there are known ways to produce the open cage without ever putting a bunny in. On the other hand, we are pretty sure that you cannotcreate the surroundings of a black hole without actually having a black hole inside.
Also note that there are murder convictions in cases where no one has watched the actual murder; often the evidence is far more indirect than the evidence of the black hole.
And no, it's not just the black pixels; there are more than enough places in the sky where you get black pixels without black holes. It is the details of the surrounding bright pixels, which behave exactly how they should if there is a black hole (and how they shouldn't if there isn't).
The Tao of math: The numbers you can count are not the real numbers.