(ORDO NEWS) — Astronomers have discovered a black hole, throwing hot material into space at a speed close to the speed of light. This flash was captured by NASA’s Chandra X-ray Observatory.
The black hole and its satellite make up the MAXI J1820 + 070 system located in our galaxy at a distance of about 10,000 light-years from Earth. The black hole in MAXI J1820 + 070 has a mass about eight times the mass of the Sun, identifying it as the so-called stellar black hole formed by the destruction of a massive star. (This is in contrast to supermassive black holes, which are millions or billions of times the mass of the sun.)
A star – a satellite orbiting a black hole, has a mass of about half the mass of the Sun. Strong black hole gravity pulls material from a companion star into the disk surrounding the black hole.
While part of the hot gas in the disk crosses the “event horizon” (point of no return) and falls into a black hole, another part of its material comes off from the black hole in a pair of short bundles of material or jets. These jets are directed in opposite directions and are launched from outside the event horizon along the lines of the magnetic field.
How fast do material jets move from a black hole? From the point of view of the Earth, it looks as if the northern jet moves at a speed of 60% of the speed of light, and the southern one – at an incredible 160% of the speed of light!
This is an example of superluminal motion, a phenomenon that occurs when something moves toward us at the speed of light along a direction close to our line of sight. This means that the object moves toward us almost as fast as the light that it generates, creating the illusion that the movement of the jet is faster than the speed of light. In the case of MAXI J1820 + 070, the south stream is directed at us, and the north stream is directed away from us, so the south stream moves faster than the north. The actual particle velocity in both jets exceeds 80% of the speed of light.
The MAXI J1820 + 070 was also observed on radio waves by a team led by Joe Bright of Oxford University, which had previously reported the detection of superlight movement of compact sources based on radio data alone.
As Chandra’s observations nearly doubled the duration of their jets, the combined analysis of radio data and new data from Chandra provided more information about jets. This included evidence that jets are slowing as they move away from the black hole.
Most of the energy in the jets is not converted to radiation, but instead is released when the particles in the jets interact with the surrounding material. These interactions can cause jets to slow down. When the jets collide with the surrounding material in interstellar space, shock waves arise – similar to sonic booms caused by a supersonic airplane. This process generates particle energies that are higher than those of the Large Hadron Collider.
Researchers estimate that about 180 thousand billion tons of material was thrown out by a black hole in these two jets launched in July 2018. This amount of mass is comparable to what can be accumulated on a disk around a black hole in space in a few hours, and this is equivalent to about a thousand Halley’s comets.
Studies of the MAXI J1820 + 070 and similar systems promise to tell us more about the jets created by stellar black holes and how they release their energy when their jets interact with the environment.
An article describing these results is published in the latest edition of The Astrophysical Journal Letters.
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