Black Hole Jets Dance to Magnetic Music

April 25, 2008 -- When it comes to getting information about a black hole, indirect paths are scientists' only option. There's just no getting around the fact that these regions of space, so dense with matter, have gravity clamps so strong that nothing, not even light, can escape.

But as black holes fly through space consuming everything within reach, they do not go unnoticed. As a black hole's prey is ripped apart, it beams out energy in patterns as distinctive as an SOS.

Scientists have wondered about one telltale sign in particular: jets of highly energized particles that spiral out from the centers of galaxies containing black holes. They suspected the phenomena were sculpted by twisted and coiled magnetic field lines.

Research published this week provides evidence they are right.

Astronomers trained an array of radio telescopes on a blazer, the most energetic type of black hole, and were able to image the throat of a spiraling jet. The target was in a galaxy called BL Lacertae, located about 950 million light-years from Earth.

The theory was that magnetic fields, which are generated as material is sucked inside a black hole, would become twisted, setting up a high-powered launch system for some particles to escape.

A black hole lines up its dinner on what are called accretion disks. These flat, spinning disks serve as departure platforms for material about to disappear -- from the perspective of Earth anyway. (Physicists have many ideas about what happens to matter inside a black hole.)