Chandra Discovered Fastest Wind From Stellar-Mass Black Holes

With the help NASA’s Chandra X-ray Observatory astronomers have clocked the fastest wind yet discovered blowing off a disk around a stellar-mass black hole.

The record-breaking wind is moving about 20 million mph, or about 3 percent of the speed of light. This is nearly 10 times faster than had ever been seen from a stellar-mass black holes. Stellar-mass black holes are born when extremely massive stars collapse. They typically weigh between five and 10 times the mass of the sun. The stellar-mass black holes powering this super wind is known as IGR J17091-3624, or IGR J17091 for short. IGR J17091 is a binary system in which a sun-like star orbits a black hole. It’s found in the central bulge of our Milky Way galaxy, about 28,000 light-years from Earth. IGR J17091’s wind matches some of the fastest generated by supermassive black holes, which are millions or billions of times more massive. Supermassive black holes are thought to reside at the heart of most if not all active galaxies, including our own Milky Way. Another surprising finding from the new study is that the wind, which comes from a disk of gas surrounding the black hole, may be blasting more material into space than the black hole is capturing. Unlike winds from hurricanes on Earth, the wind from IGR J17091 is blowing in many different directions. This pattern also distinguishes it from a jet, where material flows in highly focused beams perpendicular to the disk, often at nearly the speed of light. Simultaneous observations made with the National Radio Astronomy Observatory’s Expanded Very Large Array showed a radio jet from the black hole was not present when the ultra-fast wind was seen, although a radio jet is seen at other times. This agrees with observations of other stellar-mass black holes, providing further evidence the production of winds can stifle jets. Astronomers believe that magnetic fields in the disks of black holes are responsible for producing both winds and jets. The geometry of the magnetic fields and rate at which material falls towards the black hole must influence whether jets or winds are produced.