![]() ![]() "To compare simulations like this with EHT observations, we need to run additional calculations to translate the GRMHD data into images, too," Chan said. With this resource, the team was able to finish the full library of simulations in two months. The collaboration ran the calculations to create the library with the National Science Foundation-funded Frontera supercomputer at the Texas Advanced Computing Center, where Chan is principal investigator of the Frontera Large-Scale Community Partnerships allocation. To create the simulation library, the EHT Collaboration needed 80 million CPU hours, or processing time, which is the equivalent of running 2,000 laptops at full speed for a full year. Unlike simpler equations, which can be solved with pencil, paper and time, GRMHD equations are much more complex, as they account for the constant feedback between magnetic fields and plasma, resulting in an ever-changing equation. GRMHD simulations are similar to simulations used to understand how air flows around aircrafts, Chan said, but GRMHD simulations also factor in extreme forces of gravity as described by Einstein's theory of general relativity and the interaction between magnetic fields and plasma. The simulation process involves using supercomputers to solve what's called general relativistic magnetohydrodynamic – or GRMHD – equations, which reveal the movement of material and energy around black holes within dramatically warped space and time. The simulation that creates the snapshot with the closest match can teach us something about the actual black hole, including its plasma temperature and the strength of its magnetic field. Each simulation assumes something different about the properties and characteristics of the black hole and its surrounding environment.ĮHT scientists can compare each simulated image with the actual black hole image to find a match. ![]() This library is made up thousands of data sets – containing information about how the plasma interacts with magnetic fields around black holes – and millions of simulated images. ![]() UArizona, together with the University of Illinois and Harvard University, led the effort to create the biggest collection of simulations to date, which EHT calls the simulation library. This is the first image of Sagittarius A*, the supermassive black hole at the center of our galaxy. If Sagittarius A* was a person, it would consume a single grain of rice every million years. Also, only some of this material falls into the black hole. The electrons are 100 times cooler than the ions in the plasma, and the disk rotates in the same direction the black hole spins. This diffuse glowing disk is made up of super-heated gas, or plasma, and charged particles. The gas falling into the black hole forms a disk that, from Earth, appears to be face-on rather than from the edge. He coordinated the fifth paper, which focuses on creating black hole simulations and turning them into synthetic images that can be compared with real observations to teach us something new about the black hole.Īs a result of this process, EHT scientists determined that Sagittarius A* is likely spinning and has a magnetic field slightly stronger than a refrigerator magnet, which is enough to push away nearby gas. Chan serves as the secretary of the EHT Science Council and is a senior investigator for the international Black Hole PIRE Project, which works to develop the infrastructure to usher astronomical projects like EHT into the era of big data science.Ĭhan is also a leader of the EHT collaboration's theoretical modeling and interpretation efforts for Sagittarius A*, the subject of the latest photograph and a round scientific papers published by the EHT Collaboration in Astrophysical Journal Letters. To really understand the object we're observing, we had to compare it to simulations," said Chi-Kwan "CK" Chan, a University of Arizona associate research professor in the College of Science 's Steward Observatory. "Snapping an image is just the beginning.
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