Scientists have cultivated, on Earth, the surrounding environment of a black hole, creating a rotating disk of plasma in the laboratory. The heated gas ring imitates the matter spinning around the edge of black holes, forming the so-called “accretion disks” that gradually feed the black holes.
The experiment conducted by researchers at Imperial College London could greatly assist scientists, primarily in answering the question of how black holes grow by consuming the surrounding matter. Results of this laboratory experiment have been published in the journal Physical Review Letters (ref.).
Accretion Disk
The plasma disks were immortalized when the Event Horizon Telescope (EHT) captured the first direct image of a black hole. In the historic image of the supermassive black hole in the heart of the Messier 87 (M87) galaxy and the image of the supermassive black hole in the Milky Way, Sagittarius A*, the bright orange plasma ring surrounding the dark central black hole can be observed.
The ring forms when matter is attracted to a black hole. The immense gravitational influence creates turbulent and violent conditions, heating the gas and stripping electrons from atoms. This transforms the gas into plasma, a sea of electron-less atoms. The plasma forms an accretion disk, held in place by the outward push of centrifugal force from rotation and the inward pull of gravity.
Occasionally interrupted stability causes material to fall from the disk onto the surface of the black hole, and scientists are unsure about how these instabilities occur. This is crucial for our understanding of black holes since they cannot grow without accumulating material.
Lab Black Hole
Scientists can hardly recreate a black hole like the one in M87, which has a mass 4.5 billion times that of the Sun. However, to study the environments of these cosmic giants, the only possibility we have is to recreate the surrounding plasma in the laboratory.
To generate the black hole in the laboratory, the team used the Mega Ampere Generator for Plasma Implosion Experiments machine (MAGPIE) to spin the plasma and create an accurate replica of the accretion disks. This required accelerating eight plasma jets and causing them to collide, forming a rotating column. The scientists discovered that the plasma moves faster in the inner regions of the column, believed to be a fundamental characteristic of accretion disks.
Although it allows for better modeling of accretion disks, the experiment is merely a proof of concept, mainly because MAGPIE can only generate short bursts of plasma, limiting the team’s observations to no more than one complete rotation of the disk. Repeating the experiment with longer plasma bursts should allow the team to better characterize the accretion disks.
Role of Magnetic Fields
One of the probable mechanisms causing instability in these plasma disks is magnetic fields. These fields give rise to the friction that leads to energy loss in the matter, resulting in accretion onto the surfaces of black holes. Longer plasma bursts in the laboratory would also enable the introduction of magnetic fields into the system, allowing researchers to test this mechanism.
“We are only at the beginning of the possibility to observe these accretion disks in completely new ways, including our experiments and snapshots of black holes with the Event Horizon Telescope” said Valenzuela-Villaseca. “These will allow us to test our theories and see if they match astronomical observations”.