This is an image of galaxy M87, the same galaxy where scientists were able to produce an image of the supermassive black hole at the center. That black hole has also produced the long blue string observed in this Hubble Space Telescope image – called a relativistic jet.
This jet is a string of high-energy particles moving at nearly the speed of light. As matter falls into the black hole at the center, some portion of it is accelerated and fired out of the galaxy along its rotation axis, in part likely accelerated by the powerful magnetic field of the black hole. This string of matter is nearly 5000 light years long, and it does appear pulsed, meaning that occasionally something entering the field of the black hole triggers large eruptions.
