Goofy Black Hole Suggests We Don’t Understand How Cosmic Juggernauts Work

We thought black holes rotated in the same plane as their orbit. One that’s tilted at least 40 degrees suggests our understanding of their behavior needs updating.

Space out

February 24, 2022

Artist’s impression of the binary X-ray system containing a black hole (small black dot in the center of the accretion disk) and a companion star

Rob Hynes

A black hole rotating at a steep tilt towards the plane of its orbit suggests that we need to rethink our understanding of how they work.

Most masses in space, including black holes, spin in the same plane as they spin around nearby objects, ttypically because these nearby objects formed from the same cloud of dust or gas. If an object is tilted relative to its orbit, it may imply that something unusual happened during its formation or history.

Now Juri Poutanen of the University of Turku, Finland, and his colleagues have realized that a black hole about 10,000 light-years from Earth is tilted at least 40 degrees from the plane in which it is rotating. with its binary partner, a star with about half the mass of the sun.

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The black hole, named MAXI J1820+070, emits a faint signal of polarized light, which the researchers used to establish its orbital plane. They then used the orientation of the black hole’s radiation jets to calculate a lower bound on the black hole’s tilt. “The only explanation we have found is that the black hole’s rotation and the orbital rotation are misaligned,” Poutanen says.

This tilt could explain the observation of strange signals – called quasi-periodic oscillations (QPO) – which come from black holes. QPOs are intensity peaks at certain frequencies. A popular model suggests that these signals are the result of misaligned spins and orbits, as is the case for MAXI J1820+070, which also produces QPOs.

While it’s unclear exactly how this black hole acquired such an inclination, it’s likely that it came from instabilities when its parent supernova collapsed, Poutanen says. “During the asymmetrical collapse, you produce a kick, which means you produce [momentum]for example with neutrinos, which are ejected in one direction more than in another.

Astronomers often assume that the orbital plane and spin axis are aligned when calculating the mass and spin of black holes from observations. But if this assumption is not reliable, these calculations could be incorrect.

“If the tilt is 40 degrees or more, the results you get may be completely or significantly wrong,” says Ferdinando Patat of the European Southern Observatory.

Journal reference: ScienceDOI: 10.1126/science.abl4679

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Maria D. Ervin