Gravitational Waves Triggered 10m Years Earlier Than Thought

According to supercomputer simulations, a collision of two galaxies triggers gravitational waves about ten million years after—a much faster process than previously assumed.

AsianScientist (Sep. 16, 2016) – Gravitational waves are triggered around ten million years after the collision of two galaxies—a hundred times faster than previously assumed, finds an international research team whose research was published in the Astrophysical Journal.

In his General Theory of Relativity, Albert Einstein predicted the existence of gravitational waves, which ripple throughout space, over a century ago. This year, they were detected directly for the first time when the American Gravitational Wave Observatory LIGO recorded such curvatures in space, which were caused by the merging of two massive black holes. Until now, however, it was not possible to conclusively predict the point at which gravitational waves are triggered and spread throughout space when galaxies merge.

An international team of astrophysicists, including researchers from the Institute of Space Technology Islamabad and the Chinese Academy of Sciences, has now calculated this for the first time using an extensive simulation.

In a realistic simulation of the universe, researchers observed the merging of two roughly three billion-year-old galaxies lying relatively close to one another. Every galaxy has a supermassive black hole at its core, which can exhibit millions or even billions of solar masses. With the aid of supercomputers, the researchers calculated the time the two central black holes with around 100 million solar masses needed to emit strong gravitational waves after the galaxies collided.

The computer simulation, which took more than a year, required an innovative computational approach with various numerical codes on different supercomputers. In the process, each supercomputer was responsible for calculating a certain phase of the orbital convergence of the two massive black holes and their parent galaxies. Compared to previous models, the relation between the orbits of the central black holes and the realistic structure of the parent galaxies was factored into the present simulation.

“Our calculations therefore allow a robust forecast for the merging rate of supermassive black holes in the early stage of the universe,” explained Dr. Lucio Mayer from the Institute for Computational Science of the University of Zurich, who was involved in the project.

The article can be found at: Khan et al. (2016) Swift Coalescence of Supermassive Black Holes in Cosmological Mergers of Massive Galaxies.


Source: University of Zurich.
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