At http://phys.org/print387561473.html … the ESAs orbiting X-ray observatory has 'proved' the existence of a 'gravitational vortex' around a black hole. The study, which included NASA data from the NuSTAR mission, has solved a 30 year mystery we are told. The theory is that as matter falls into a black hole it heats up as it plunges into doom, swallowed by the black hole. At that point of very high temperature it shines x-rays into space.
In the 1980s astronomers discovered these x-rays flicker. They felt compelled to explain the phenomenon and gave it the name Quasi Periodic Oscillations and these appeared to be coming from the majority of proposed black holes, gaining momentum before eventually stopping. In the 1990s the explanation was that the flashing light was caused by spinning – and then that a spinning object will create a gravitational vortex. In 2004 NASA launched Gravity Probe B, a clever experiment that confirmed a spacecraft would turn through a complete precession over 33 million years, solely as a result of gravity. However, around a black hole gravity is thought to be much greater and the precession takes just a few seconds. In other words, prior to the latest findings scientists were expecting to find evidence linking Quasi Periodic Oscillations with that increased gravity assumed to be part of the black hole phenomenon. They hypothesized that the flat disc of matter surrounding a black hole behaved as an oscillating disc, where material spirals towards doom. Mainstream already considered that close to the black hole the accretion disc became hot plasma in which electrons are stripped from their hot atoms. This is the so called 'hot inner flow' and is what is consumed by the black hole. The new findings are said to prove the theory and inner flow is releasing high energy radiation that strikes matter in the outer accretion disc making iron atoms and these shine like a flourescent light tube. The iron releases x-rays of a single wavelength – known as a 'spectral line' and because the accretion disc is rotating the spectral line has its wavelength distorted by the Doppler Effect. If the inner flow is precessing it will sometimes shine on the approaching disc material and sometimes on the receding material making the spectral line wobble back and forth. This is basically what the ESA x-ray observatory sees as a wobble (confirmed by NASA NuSTAR). Scientists now say 'we are directly measuring the motion of matter in a strong gravitational field near a black hole which is reflected in the title of the study that will be published in the Monthly Notices of the Royal Astronomical Society B.