11/17/2022 Jessica Raley for ICASU
Illinois Physics undergraduate student Mit Kotak won first place in the Image of Research competition in the spring of 2022. Now his award-winning image, “3D Visualization of Binary Black Hole Merger” has been selected by the Coalition for Academic Scientific Computation (CASC) for inclusion in their annual brochure.
Written by Jessica Raley for ICASU
Illinois Physics undergraduate student Mit Kotak won first place in the Image of Research competition in the spring of 2022. Now his award-winning image, “3D Visualization of Binary Black Hole Merger” has been selected by the Coalition for Academic Scientific Computation (CASC) for inclusion in their annual brochure.
An education non-profit, CASC comprises more than 100 universities and scientific computing centers, including the National Center for Supercomputing Applications (NCSA) at the University of Illinois Urbana-Champaign. The brochure will be featured in the annual international supercomputing conference, which takes place in Dallas this month.
Kotak is a member of Illinois Physics and Astronomy Professor Stu Shapiro’s theoretical astrophysics and general relativity undergraduate research team. Shapiro’s group specializes in using supercomputers to simulate mergers of compact astrophysical objects—black holes and neutron stars. Scientists at Illinois Physics and elsewhere use these simulations to interpret data from large-scale experiments, including the Laser Interferometer Gravitational Wave Observatory (LIGO). The simulations performed here will be particularly useful for future gravitational wave observations from the planned Laser Interferometer Wave Observatory (LISA) that will be launched from space.
Kotak’s visualization is based on a computer simulation of two black holes orbiting around one another until they finally collide and merge. A disk of gas swirls around the outside of this binary system.
The motivation for this simulation was to provide information about the gravitational waves, and the electromagnetic counterpart radiation, including the launching of relativistic jets from the poles of the black holes. In particular, the purpose of this simulation was to explore a potential cause of X-shaped galaxies. These galaxies have vast streams of radio waves that shoot out in an “X” pattern from the central black hole. Scientists do not fully understand what causes some galaxies to take this shape, though several hypotheses have been developed.
One hypothesis about what causes X-shaped galaxies is that the spin of the black hole changes after the merger. Kotak says, “During the merger, the jets of the individual black holes will induce the emergence of a new jet along the direction of the black hole remnant’s spin. If the spin of the remnant black hole following merger points in a different direction from the spin of the primary black hole prior to merger, the jet direction will change and may exhibit an X-shaped kink."
Shapiro’s group uses computer simulations to test this hypothesis. To create the image, Kotak and his colleagues used supercomputing resources at NASA Ames Research Center, the Extreme Science and Engineering Discovery Environment (XSEDE), and the Texas Advanced Computing Center (TACC). The key simulations were performed by Shapiro and his collaborators Milton Ruiz and Antonios Tsokaros. Kotak, and his undergraduate research team colleagues—Eric Yu, Jinghan Huang, Jing Zhou—were primarily responsible for constructing the visualizations.
Shapiro says, “For this simulation we used our ‘Illinois GRMHD’ numerical relativity computer code, which solves Einstein’s equations for the gravitational field simultaneously with the equations of relativistic magnetohydrodynamics for the fluid and Maxwell’s equations for the magnetic field. These equations determine the evolution of the black hole, the gaseous disk, and the magnetic field before, during, and after the merger. Cosmic scenarios like this one provide the essential ingredients for ‘multi-messenger astronomy.’ In this case, electromagnetic radiation from the disk and jet, along with gravitational waves from the black holes orbiting one another, provide two sources of information from the same event.”
Kotak says, “This work has played an important role in shaping my future goals. Having seen how supercomputers can accelerate, or in this case open up research directions that weren’t accessible before, I am now applying to graduate schools with the broad goal of using supercomputing to solve problems in science and engineering.”
The full text of the CASC brochure can be found here. Kotak’s image is on page 14.