Astronomers recreate super speedy rings surrounding black holes in lab

Recreating the plasma disc

An accretion disc is made up of superheated gas that swirls at incredible speeds around the event horizon of a black hole — a boundary that marks the outer edge of the black hole from which not even light can escape.

The iconic photograph of M87* shows an accretion disk with a blurred halo of the orange glow surrounding a supermassive black hole.

The team used the Mega Ampere Generator for Plasma Implosion Experiments machine (MAGPIE) to simulate the disc spin of a black hole. 

The MAGPIE machine created rings by accelerating eight plasma jets and then colliding them, resulting in the formation of a spinning column — similar to what happens around a black hole. The plasma ring closer to the spinning column's center rotated much faster than the one closer to its edge, as known in the actual accretion discs.

The authors hope that this experiment will shed light on one of the most perplexing aspects of accretion disks: how does a black hole grow if material remains in a stable orbit around the event horizon rather than falling into it?

As per the official release, one leading hypothesis is based on the “instabilities in magnetic fields in the plasma cause friction, causing it to lose energy and fall into the black hole.” 

Future experiments using this facility may ultimately be able to better decode this mystery. 

Dr. Valenzuela-Villaseca concluded: “We are just as the start of being able to look at these accretion discs in whole new ways, which include our experiments and snapshots of black holes with the Event Horizon Telescope. These will allow us to test our theories and see if they match astronomical observations.”

The study details have been published in the journal Physical Review Letters.

Study abstract:

We present results from pulsed-power driven differentially rotating plasma experiments designed to simulate physics relevant to astrophysical disks and jets. In these experiments, angular momentum is injected by the ram pressure of the ablation flows from a wire array Z pinch. In contrast to previous liquid metal and plasma experiments, rotation is not driven by boundary forces. Axial pressure gradients launch a rotating plasma jet upward, which is confined by a combination of ram, thermal, and magnetic pressure of a surrounding plasma halo. The jet has subsonic rotation, with a maximum rotation velocity 23±3  km/s. The rotational velocity profile is quasi-Keplerian with a positive Rayleigh discriminant κ2∝r−2.8±0.8  rad2/s2. The plasma completes 0.5–2 full rotations in the experimental time frame (∼150  ns).