Remarkable Symmetry in Black Hole Jets |
Black holes range from modest objects formed when individual stars end their lives to behemoths billions of times more massive that rule the centers of galaxies. A new study using data from NASA’s Swift satellite and Fermi Gamma-ray Space Telescope shows that high-speed jets launched from active black holes possess fundamental similarities regardless of mass, age or environment. The result provides a tantalizing hint that common physical processes are at work.
"What we’re seeing is that once any black hole produces a jet, the same fixed fraction of energy generates the gamma-ray light we observe with Fermi and Swift," said lead researcher Rodrigo Nemmen, a NASA Postdoctoral Program (NPP) fellow at NASA’s Goddard Space Flight Center in Greenbelt, Md.
Gas falling toward a black hole spirals inward and piles up into an accretion disk, where it becomes compressed and heated. Near the inner edge of the disk, on the threshold of the black hole’s event horizon — the point of no return — some of the material becomes accelerated and races outward as a pair of jets flowing in opposite directions along the black hole’s spin axis. These jets contain particles moving at nearly the speed of light, which produce gamma rays — the most extreme form of light — when they interact.
"We don’t fully understand how this acceleration process occurs, but in active galaxies we see jets that have operated so long that they’ve produced trails of gas extending millions of light-years," said Sylvain Guiriec, an NPP fellow at Goddard and a co-author on the study, which was published in the Dec. 14 issue of Science. continue reading