Black holes reveal more secrets

The researchers studied a black hole just as it was sending forth a jet

Scientists say they have unlocked some of the secrets behind black holes, the gravitational fields known for sucking up light and stars from the Universe.

In a report in the journal Nature, US researchers say they have worked out how black holes emit jet streams of particles at close to light speed.

The Boston University team say the streams originate in the magnetic field near the edge of the black hole.

They say it is within this region that the jets are accelerated and focused.

Despite the fact that it is probable that a black hole lurks at the centre of our Milky Way galaxy, astronomers still know very little about these celestial monsters which vacuum up almost everything in their path, even light.

Professor Alan Marscher of Boston University and colleagues claim they have delved deeper than ever into their heart.

Using almost every type of telescope known to humankind, Prof Marscher believes he has worked out where and how the jets - or blazars - are formed.

Using an array of 10 powerful radio telescopes, aimed at the galaxy BL Lacertae, the researchers studied a black hole just as it was sending forth a blazar jet.

The astronomers had suspected that the supermassive black hole was spewing out plasma jets in a winding corkscrew, and they say that their observations have now confirmed just that.

"We have gotten the clearest look yet at the innermost portion of the jet, where the particles actually are accelerated," Prof Marscher said in a statement.

University of Michigan astronomy professor Hugh Aller, who worked on the project, told Reuters news agency that the process of accelerating the material to nearly the speed of light was similar to what happened in a jet engine.

"We think it is focused by a nozzle of sorts and it comes out at us," he was quoted by Reuters as saying.

However, the BBC's science correspondent Neil Bowdler says despite this breakthrough, scientists are no closer to finding what lies within the black hole - beyond what is called the event horizon

In fact, if the theoretical physicists are right, our correspondent says, then we will never be able to see inside these strange phenomena.