Feeding the Dark Black Hole at the Core of our Galaxy

Researchers at the Princeton University and the U.S. Department of Energy’s DOE Princeton Plasma Physics Laboratory have introduced a stringent method for structuring the accretiondisk that feeds the supermassive black hole at the centre of our Milky Way galaxy. The paper offers a much – required foundation for simulation of the extraordinary procedures involved.

Accretion disks are plasma clouds that revolve and gradually swirl into huge bodies like black holes – intense gravitational fields released by stars that collapse to a small fraction of their original size. Such collapsed stars are confined by an event horizon from which not just light can escape. As accretion disks rotate towardevent horizons, theyoffer power few of the energetic and brightest sources of electromagnetic radiation in the universe.

The dark black hole at the centre of Milky Way, known as Sagittarius A, as it was found in the constellation Sagittarius has a gravitational mass that is four million times bigger than our own sun. Yet the accretion disk plasma that rotates into such mass is radiates ineffective, implying that it releases much less radiation than one would consider.

“So the question is why such disk is so quiescent?” asks Matthew Kunz, a head author of the paper, an assistant lecturer of astrophysical sciences at the Princeton University and a researcher at PPPl. Co-authors comprise James Stone, Princeton lecturer of astrophysical sciences and Eliot Quataert, director of theoretical astrophysics at the University of California, Berkeley.

To introduce a technique for finding the answer, the scientists considered the nature of the superhot Sagittarius A accretion disk. Its plasma is so dilute and hot that is collisionless, implying that the trajectories of electrons and protons inside the plasma rarely intersect.

For modelling the process for Sagittarius A, the paper substitutes the formulas that treat the movement of collisional plasmas as a macroscopic fluid. Rather, the authors utilize a method that physicists consider ‘kinetic; to systematically track the paths of separate collision less particles. Such intricate approach, conducted utilizing the Pegasus computer code introduced at the Princeton by Kunz, Xuening and Stone Bai, now a lecturer at Harvard University, released a set of equations better able to model behaviour of the disk that revolves around the supermassive black hole.