Creating Black Hole Jets With a NASA Supercomputer

SYNOPSIS

NASA Goddard astrophysicists Ryan Tanner and Kim Weaver have used the NASA Center for Climate Simulation's Discover supercomputer to simulate weak jets produced by monster black holes, which can weigh up to billions of times the Sun's mass. As matter falls toward the black hole, some of it accelerates to near light speed and diverts into a narrow pair of jets flowing in opposite directions. In the grandest examples, these jets extend hundreds of thousands of light-years and are easily detected features in radio. But weaker jets, which are more difficult to detect, can greatly impact the central regions of their host galaxies. Astronomers suspected weak jets might be responsible for unusual gas motions or otherwise unexplainable optical and X-ray emission in some black-hole-powered galaxies. So Tanner and Weaver simulated weak jets under realistic conditions for a galaxy about the mass of our own Milky Way. To represent the gas distribution and properties related to the black hole's activity, they referenced spiral galaxies such as NGC 1386, NGC 3079, and NGC 4945. Tanner modified existing astrophysical hydrodynamics code to explore how the jets and the gas impact each other across 26,000 light-years of space, or about a quarter the diameter of the Milky Way, and 600,000 years of time. From the full set of 100 simulations, the team selected 19 – which consumed 800,000 core hours on Discover – for publication. The final form of these outflows depends mainly on their interactions with large, dense gas clouds in the galaxy's central region. These clouds can disrupt, deflect, split, or even suppress the jet. This atlas of simulations provides an important touchstone for better understanding how weaker, less apparent jets modify their galaxies.