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It seems the more we learn about black holes, the more there is to find out. In this case, what in the universe could have put one on its side?

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This episode of SciShow is sponsored by Endel, an app that creates personalized soundscapes to help you focus, relax, and sleep. The first 100 people to download Endel using the link in the description will get a free week of audio experiences.

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Here at SciShow Space, we just cannot escape the pull of a good black hole story. We've talked before about extremely big black holes, fast-spinning black holes, planets around black holes. But our favorite weird black hole, at least for now, was described by a team of astronomers led by a Finnish university. They found a black hole about 10.000 light years away, that was spinning on its side.

This discovery was so unexpected that it might turn our understanding of black holes on its head.

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But first let's be clear by what we mean when we say that the black hole is on its side. Here we are comparing its axis of rotation, or how it spins on its own axis, with its axis of orbit, or how it moves around something else. Because in this black hole's case, there are more than 40 degrees out of whack with each other. See, like many black holes, this one has a partner star it's in mutual orbit with.

The pair make a binary system. The researchers could tell that, because it has a large disk of glowing, hot gas around it called an accretion disk, which comes from material that the black hole is consuming from its stellar partner.

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And, also like most black holes, this one is spinning. We know that because it was observed emitting an outburst of material in what's known as a jet. Jets are immense bursts of energy from astrophysical objects, emitted in very tight beams. And what's interesting about black hole jets is that they seem to fire from their poles.

They happened when the charged particles and intense energy in the accretion disk generate massive magnetic fields. These magnetic fields are then dragged by the black hole's spin and funnel material from the disk to the poles of the black hole and then out into space. So by looking at the direction a jet is shooting in, you can tell the black hole's axis of rotation.

So usually when a thing in space is both spinning and in orbit around something else, the axes of rotation are pretty aligned. Meaning, it spins along roughly the same plane that it orbits on. And that makes sense, as things in orbit, as things in orbit tend to form from the same disk of spinning gas, and gravity has a tendency to tug things into alignment that way.

In our solar system, for instance, seven of the eight planets, have axial tilts under thirty degrees; their orbit and rotation are pretty lined up. Earth's tilt is around twenty-three degrees, and the sun itself orbits only seven degrees off the orbital axis of the planets. There is one very famous exception.

Uranus is over ninety degrees out of alignment. It's rotating almost perfectly on its side relative to the axis of orbit. And while the exact cause of that is unknown, astronomers agree that something funky must have happened to it in the past, like a large collision.

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Which brings us back to this black hole. Something weird must have happened because its rotational axis is at least 40 degrees out of alignment with its orbital one. But unlike Uranus, this things is eight times heavier than the sun. So it doesn't just get knocked around by anything.

To learn all of this, the Finnish team worked out the black hole's axis of rotation by studying in detail the jets it emitted in 2018. But then, they also looked at the binary system between bursts of jets, when the partner star was more visible. From that, they could also study its light, look at how red- and blue-shifted it was to work out its velocity, and then use that to infer its axis of orbit around the black hole.

Then they looked at the polarization of the light from the accretion disk, and that gave them information about the direction the light was emitted from. That last piece allowed them to work out how the binary system was oriented in the night sky relative to us-- the last piece of the puzzle in working out the axis of rotation. With all of that, they inferred that the misalignement between the two axes was at least forty degrees, possibly even as much as sixty degrees.

That's not Uranus levels of flopped over on its side, but it's pretty short of upright. And the researchers are still kind of in the dark about just what the heck could have caused such a huge misalignment.

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But there is evidence that large 'kicks' to black holes could be pretty common in their formation, possibly during the initial supernova that created them. And something like that seems to be the case here. After all, misalignments like that should decrease as time goes on. As the black hole continues accreting material, its gravity should eventuall drag everything into alignment.

But while researchers try to pin down what caused this big misalignment, they'll also be busy updating some astrophysical models. Before now, most models about how black holes form and interact assumed that these misalignments were always small. But this new discovery calls that into question.

For instance, the misalignment could cause significant wobbling in the orbit of the two objects, and that could affect how they emit gravitational waves. So if we want to get better at spotting gravitational waves, we will need to assume that there could be large misalignments when simulating these systems. In other words, we'll need to start looking at black holes from a whole new angle.

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