spaceSpace and Physics

Jets Blasted To 80% The Speed Of Light From A Black Hole Caught On Film


The location of the event is marked by a cross on an optical and infrared image, whilst the corner image shows the first X-ray observation of the black hole outburst. NASA/CXC/Université de Paris/M. Espinasse et al./PanSTARRS

Jets blasted outwards from a stellar-mass black hole at 80 percent the speed of light have been caught on film by NASA’s Chandra X-ray Observatory.

MAXI J1820+070, the black hole in question, is located 10 million light-years from Earth and has a mass approximately eight times that of the Sun. Four separate observations of this cosmic object, between November 2018 and June 2019, allowed astronomers to map the black hole’s outburst in X-rays. To date, only two other examples of such flare-ups have been seen from stellar-mass black holes in this region of the electromagnetic spectrum.


This extraordinary eruption was powered by in-falling matter from MAXI J1820+070’s companion star, which has about half of the mass of the Sun. Pulled in by the black hole’s strong gravitational field, this material surrounds the dense object in an X-ray emitting disk. Some of this hot gas will inevitably cross the black hole’s event horizon, sucked into the point of no return. However, some of the hot material will be hurled away in a pair of jets along magnetic field lines – which this new video has enabled us to see.

Day "0" of observations begins 4 months after the jet's launch. In the latter observations, the southern jet becomes too faint to be detected. NASA/CXC/Université de Paris/M. Espinasse et al.

As detailed in The Astrophysical Journal Letters, the researchers, led by Mathilde Espinasse of the Université de Paris, predict the combined mass of material in the jets was approximately 400 million billion pounds. To put that into context, that is roughly equivalent to 500 million Empire State Buildings. Wild.

Another mind-blowing detail was the speed at which the jets appeared to travel. From our perspective on Earth, the northern jet seemed to travel at around 60 percent the speed of light whilst the southern one clocked in at a 160 percent the speed of light. But this was no mistake on the astronomer’s part, rather it was an example of superluminal motion.

Superluminal motion is a phenomenon when jets travel almost as quickly towards an observer as the light it generates does. This creates an illusion that the jet surpasses the speed of light – such is the case with MAXI J1820+070’s southern jet, and therefore seems to outpace the northern jet as well. However, the actual speed of both jets is just over 80 percent the speed of light (about 500 million miles per hour) – which is still mighty impressive.


The latest observations of MAXI J1820+070 from the Chandra Observatory are built on previous radio detections of the same jets by a team led by Joe Bright from the University of Oxford. Using both sets of data, Espinasse and her team learned that the jets were also decelerating as they traveled away from the black hole. They believe that this could be caused by the jet material’s interaction with the surrounding matter, which is where most of its energy is released.

A further look at MAXI J1820+070 and similar stellar-mass black hole systems will help astronomers to advance their understanding of the jet’s phenomenal energy transfer to their surroundings.


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