The gravitational area of a rotating black gap is highly effective and unusual. It’s so highly effective that it warps house and time again upon itself, and it’s so unusual that even easy ideas corresponding to movement and rotation are turned on their heads. Understanding how these ideas play out is difficult, however they assist astronomers perceive how black holes generate such great power. Take, for instance, the idea of body dragging.
Black holes type when matter collapses to be so dense that spacetime encloses it inside an occasion horizon. This implies black holes aren’t bodily objects in the best way they’re used to. They aren’t made from matter, however are slightly a gravitational imprint of the place matter was. The identical is true for the gravitational collapse of rotating matter. Once we speak about a rotating black gap, this doesn’t imply the occasion horizon is spinning like a prime, it signifies that spacetime close to the black gap is twisted right into a gravitational echo of the as soon as rotating matter. Which is the place issues get bizarre.
Suppose you have been to drop a ball right into a black gap. Not orbiting or rotating, only a easy drop straight down. Fairly than falling in a straight line towards the black gap, the trail of the ball will shift towards an orbital path because it falls, shifting across the black gap ever quicker because it will get nearer. This impact is called body dragging. A part of the “rotation” of the black gap is transferred to the ball, despite the fact that the ball is in free fall. The nearer the ball is to the black gap, the higher the impact.
A latest paper on the arXiv exhibits how this impact can switch power from a black gap’s magnetic area to close by matter. Black holes are sometimes surrounded by an accretion disk of ionized fuel and mud. As the fabric of the disk orbits the black gap, it could generate a robust magnetic area, which might superheat the fabric. Whereas a lot of the energy generated by this magnetic area is brought on by the orbital movement, body dragging can add an additional kick.
Basically, a black gap’s magnetic area is generated by the majority movement of the accretion disk. However thanks to border dragging, the interior portion of the disk strikes a bit quicker than it ought to, whereas the outer portion strikes a bit slower. This relative movement between them signifies that ionized matter strikes relative to the magnetic area, making a form of dynamo impact. Thanks to border dragging, the black gap creates extra electromagnetic power than you’d count on. Whereas this impact is small for stellar mass black holes, it’s giant sufficient for supermassive black holes that we would see the impact in quasars via gaps of their energy spectrum.
Reference: Okamoto, Isao, Toshio Uchida, and Yoogeun Tune. “Electromagnetic Power Extraction in Kerr Black Holes via Body-Dragging Magnetospheres.” arXiv preprint arXiv:2401.12684 (2024).
