It is currently believed that many, if not all, galaxies have supermassive black holes at their centers. In general, matter and light that come near enough to a black hole will never make it back. Some supermassive black holes, however, have jets of super high-velocity matter streaming out from the center of the black hole's accretion disk. The behavior of these relativistic jets has long been a mystery in the astrophysics world.





CREDIT: Marscher et al., Wolfgang Steffen,

Cosmovision, NRAO/AUI/NSF

Theories that attempt to explain the relativistic jets suggest that the magnetic field in the vicinity of the black hole is incredibly twisted by the dynamics of the black hole's warping of space itself. It is believed that a fraction of the matter captured in the black hole's accretion disc is accelerated to near light speeds by these tightly wound magnetic fields, forming a spiral of particles that is ejected from the area of the black hole.

Until recently, no observations were able to confirm this explanation for the relativistic jets. A paper published in the April 24th edition of Nature describes how researchers from around the world, led by Boston University researcher Alan Marscher, used the National Radio Astronomy Observatory's Very Long Baseline Array to directly look into the region of a relativistic jet that's closest to the accretion disk. "We have gotten the clearest look yet at the innermost portion of the jet, where the particles actually are accelerated, and everything we see supports the idea that twisted, coiled magnetic fields are propelling the material outward," said Marscher.

The observations come from a blazar galaxy, BL Lacertae (BL Lac), about 950 million light years from Earth. In addition to seeing the coiled structure, the team was able to see flares that were predicted to occur when the ejected material hit a stationary shock wave some time after it left the immediate vicinity of the black hole. Further support for the current theory came when bursts of light, X-rays and gamma rays appeared right when theory predicted. According to Marscher, "we got an unprecedented view of the inner portion of one of these jets and gained information that's very important to understanding how these tremendous particle accelerators work."

Nature, 2008. DOI: 10.1038/nature06895