Black hole mystery mimicked by supercomputer
Posted: January 27, 2002

  Black hole
This three-dimensional illustration shows how the rotating space around a black hole twists up the magnetic field in the plasma falling toward the black hole. The black sphere at the center of the figure is the black hole itself, and the yellow region around it represents the area where space is being twisted. The red tubes depict magnetic field lines threading this twisting space, while the green ones show magnetic field lines which have not yet entered that space. Photo: NASA/JPL
Advanced supercomputers have simulated extremely powerful energy jets squirted out by black holes, the most exotic and powerful objects in the Universe.

"This research helps us unlock the mysteries of rotating black holes and confirms that their rotation actually produces power output," said Dr. David Meier, an astrophysicist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. Meier is co-author of a paper that will appear in the journal Science. The leader of the research team is Dr. Shinji Koide of Toyama University, Toyama, Japan.

A black hole is an object so dense and powerful that nothing, not even light, can escape. A black hole gobbles up stars and other material that approaches it, including other black holes. These odd objects form in one of two ways -- when a dying star collapses, or when many stars and black holes collapse together in the center of a galaxy, like our Milky Way.

Both types of black holes can rotate very rapidly, dragging along the space around them. When more material falls in, it swirls and struggles wildly before being swallowed. Astronomers have witnessed this violence, including the ejection of jets, with radio and X-ray observations, but they are not able to see a black hole itself.

"We can't travel to a black hole, and we can't make one in the lab, so we used supercomputers," Meier said. This simulation process is similar to weather-prediction techniques, which create animation of how clouds are expected to move, based on current satellite views and knowledge about Earth's atmosphere and gravity effects. In much the same way, the scientists combined data about plasma swirling into a black hole with knowledge about how gravity and magnetic fields would affect it.

"We have modeled a rotating black hole with magnetized plasma falling into it," said Koide. "We simulated the way that the magnetic field harnesses energy from the rotation of the black hole."

"In this case, jets of pure electromagnetic energy are ejected by the magnetic field along the north and south poles above the black hole," Meier added. "The jets contain energy equivalent to the power of the Sun, multiplied ten billion times and then increased another one billion times."

Black hole
This graphic shows the computer simulation of a black hole from start to finish. Plasma is falling slowly toward the black hole in a (at the upper left). The plasma has a magnetic field, shown by the white lines. It picks up speed as it falls toward the hole in b (at the upper right), c (lower left) and d (lower right). However, the rotating black hole twists up space itself (and the magnetic field lines) and ejects electromagnetic power along the north and south poles above the black hole. The red and white color shows the immense electromagnetic power output, which eventually will pick up particles and form squirting jets. Photo: NASA/JPL
This jet phenomenon had been predicted by Professor Roger Blandford of the California Institute of Technology, Pasadena, Calif., and his colleague, Roman Znajek, in the 1970s, but the new computer simulation confirms that prediction. The latest research was conducted in late 2001 using supercomputers at Japan's National Institute for Fusion Science.

Scientists have theorized the existence of black holes since the 1700s and identified jet-producing objects in the centers of galaxies since the early 1900s. In the 1960s, scientists explored the possibility that these jet-emitting objects were supermassive black holes between one million and several billion times heavier than our Sun. In the 1990s, it was discovered that such jets also are ejected by much smaller black holes in double star systems. A black hole ten times as massive as the Sun can form when the center of a dying star, 20 to 30 times the mass of the Sun, collapses on itself. This creates a tiny object, only a few miles across, with an intense gravitational pull. The other supermassive type of black hole is formed when many stars and black holes collapse together in the center of a galaxy.

In addition to Koide and Meier, the team includes colleagues Dr. Kazunari Shibata, Kyoto University, Kyoto, and Dr. Takahiro Kudoh, National Astronomical Observatory, Mitaka.

The research was partially funded by an Astrophysics Theory Grant from NASA. The California Institute of Technology in Pasadena manages JPL for NASA.