Two Black Hole Jets Gushing Out at 80% Light Speed

The star accompanying the black hole is roughly half the mass of the sun, but unlike ours, it experiences a gravitational pull so strong that material is lifted up and away toward the black hole — forming an X-ray-emitting disk around the big hole in the sky.

Some of the ultra-hot gas in the disk surrounding the black hole will cross the event horizon (the deadly point of no return), but other portions of the gas are launched back out into space in a pair of short beams or jets of material. The ultra-hot (and radioactive!) jets are pointed in opposite directions and gush from outside the event horizon along magnetic field lines.

New footage of the black hole's gushy behavior came from four observations gathered with Chandra in November 2018 and February, May, and June of last year — as reported in a paper from the Université de Paris.

Hot gas moving at 80% lightspeed

The primary panel of the top image is a large optical and infrared image of the Milky Way galaxy produced with the PanSTARRS optical telescope in Hawaii. The MAXI J1820+070 is above the plane of the galaxy, marked with crosshairs.

The inset image is clipped from a movie that cycles through the four Chandra observations described above — with "day 0" corresponding to the first observation on November 13, 2018 — roughly four months following the jet's launch. The black hole itself is the bright X-ray light in the middle of the image, from which X-rays gush away in both north and south jets.

MAXI J1820+070 is a fixed point source of X-rays, although it looks larger because of the brightness gradient. The southern jet is too faint to see in the May and June 2019 captures.

While from Earth the north jet appears to move at 60% of the speed of light, and the southern one at 160% speed of light, this is actually an optical illusion of sorts — called superluminal motion — a phenomenon that happens when something moves toward us at close to the speed of light, near our line-of-sight.

Since the material ejected from the black hole is moving toward us almost as fast as the light it emits, this creates the illusion that the gushing jet motions have a velocity exceeding the speed of light. The real velocity of both jets is still high — at greater than 80% of the speed of light.