ESA’s Integral gamma-ray observatory has spotted apparently-doomed hot matter just a millisecond before plunging into a black hole – but says it appears that some of the matter may be escaping.
The new observations show that the region is permeated by magnetic fields – the first time magnetic fields have been identified so close to a black hole – and that these fields are forming an escape tunnel for some of the doomed particles.
It seems that the magnetic field is strong enough to tear away particles from the black hole’s gravitational clutches and funnel them outwards, creating jets of matter that shoot into space. The particles in the jets are drawn into spiral trajectories, affecting their polarisation; and it’s this polarisation that the team have found in the gamma rays.
It was a difficult observation to make, says Philippe Laurent of CEA Saclay in France. “We had to use almost every observation Integral has ever made of Cygnus X-1 to make this detection,” he says.
“We still do not know exactly how the infalling matter is turned into the jets. There is a big debate among theoreticians; these observations will help them decide.”
Jets around black holes have been seen before by radio telescopes but such observations cannot see the black hole in sufficient detail to know exactly how close to the black hole the jets originate. That makes these new observations invaluable.
“This discovery of polarized emission from a black hole jet is a unique result demonstrating that Integral, which is covering the high-energy band in ESA’s wide spectrum of scientific missions, continues to produce key results more than eight years after its launch,” says Christoph Winkler, ESA Integral project scientist.
