Black hole blinked with a radio flare express
A black hole paired with a star works like a pump: it pulls gas from its companion, swirls it into a glowing disk, and occasionally ejects some of that matter in two narrow jets. In 2021, the system 4U 1543-475 put on such a show. Radio telescopes caught two short radio bursts — traces of ejections that astronomers attribute to the black hole, though in reality they are jets born near it.
In the same days, X-ray telescopes noticed that the emission became harder: the thermal glow of the disk was joined by a contribution from a cloud of hot electrons — the corona. The reflection of this hard light from the inner parts of the disk weakened by a factor of three to four. That means the geometry of the inner flow changed for a short time: the disk may have receded, and the corona may have puffed up. Optical observations also showed variability similar to the reflected component.
The exact sequence of events could not be established: there were not enough simultaneous data. But one thing is clear: the jet does not live on its own. It is born when the disk and corona reconfigure. 4U 1543-475 gave a rare chance to see this reconfiguration simultaneously in radio, X-ray, and optical bands.
The distance to 4U 1543-475 is about 24,000 light-years, and the 2021 outburst was noticed even by small amateur telescopes: the system brightened in optical light.
In Interstellar, the black hole Gargantua is surrounded by an accretion disk, and its glow changes as the heroes approach — similar to the variability astronomers catch in real binary systems.