Supernovae that originate from the collapse of massive stars and are the power behind gamma-ray bursts have them. Supermassive black holes at the centers of galaxies have them. And so too do stellar mass black holes that are the remnants of supernovae that flared long ago. Jets. Intense jets of radiation and particles moving at nearly the speed of light.
Jets occur frequently in objects of interest to researchers working on high-energy astrophysics. Yet they still aren’t well understood. GX 339-4 is the designation given to a black hole with a mass about 6 times that of our Sun and located 20,000 light years away.
NASA’s Wide-field Infrared Survey Explorer (WISE) records images covering the whole sky every 11 seconds. This made it possible to capture repeated images of a small area around GX 339-4 at the base of its jets. Its jets are fueled by an accretion disk which in turn is fed by gas sucked from a companion star. What was surprising about the observations was the wide variability of both the size and the brightness of the small region where the jets originate.
The results surprised the team, showing huge and erratic fluctuations in the jet activity on timescales ranging from 11 seconds to a few hours. The observations are like a dance of infrared colors and show that the size of the jet’s base varies. Its radius is approximately 15,000 miles (24,140 kilometers), with dramatic changes by as large as a factor of 10 or more.
“If you think of the black hole’s jet as a firehose, then it’s as if we’ve discovered the flow is intermittent and the hose itself is varying wildly in size,” Poshak said.
The new data also allowed astronomers to make the best measurements yet of the black hole’s magnetic field, which is 30,000 times more powerful than the one generated by Earth at its surface. Such a strong field is required for accelerating and channeling the flow of matter into a narrow jet. The WISE data are bringing astronomers closer than ever to understanding how this exotic phenomenon works.