Since the accidental detection of gamma-ray bursts (jets) in 1967 by the American military satellite Vela, scientists have not stopped guessing about the nature of such phenomena. Later it turned out that the source of high-energy bursts are, in particular, black holes. But there was no unambiguous interpretation of the event until recently, when a group of astrophysicists informed about the facts confirming one of several models of jet acceleration.
Strictly speaking, two theories of the acceleration of jets – the brightest flashes visible from the Earth in all the observed ranges of electromagnetic waves from X-ray to visible and infrared, as well as in the radio range – are most widely used. If such a flash originated in our galaxy and was directed in our direction, life on Earth would be blown out like a candle during a hurricane. Fortunately, they occur extremely rarely in galaxies, and an indispensable condition must be met – the energy jet must be directed at us (in fact, in other cases, jets are not corny registered).
According to one theory, the acceleration of jets occurs in the process of changes in magnetic fields – something like an electromagnetic lens, which gives high-energy particles additional acceleration. Another theory interprets the acceleration of particles to near-light speeds in the process of interaction of matter in the jet with matter surrounding the black hole. It’s like a pressure washer, where a narrow nozzle gives the jet extra acceleration. Energetic particles ejected from the poles of a black hole collide with matter or with each other, which gives them additional energy and accelerates even more.
Note that the process of the emergence of jets (jets) is separate issue. Jets draw their energy from accretion disk – falling on the black hole of matter from the surrounding space. The new study dealt only with the issue of acceleration of particles in a jet to the recorded transcendental energy values. NASA’s new X-ray telescope IXPE, launched into orbit, helped solve the mystery December 9, 2021. It is the first instrument in space that can measure polarization x-ray radiation. Polarization data make it possible to understand how and in what direction electromagnetic waves propagate, which makes it possible to refine mathematical models of cosmic phenomena.
Using the IXPE telescope, astrophysicists studied the X-ray component of the jet blazar Markarian 501 (the Markarian 501 galaxy in the constellation Hercules). This object – a black hole in the center of the galaxy – is located at a distance of 450 million light years from us and is oriented by the ejection of a jet to Earth. Previously, the polarization of the Markarian 501 jet was measured by astronomers for the optical and radio ranges.
When new data on the polarization of the X-ray range were added, it turned out that the polarization is most pronounced in this range, and it decreases with the transition to the optical and radio ranges. Thus, scientists have discovered the area in which the particles of the jet are accelerated – the very “nozzle” that gives the jet additional acceleration.
As the simulation showed, the energy for acceleration is the energy of the shock wave of the jet. The particles of the jet begin to move faster than the particles of the surrounding matter – a similar phenomenon we observe when a supersonic aircraft overcomes the sound barrier – and the shock wave formed in the process gives the particles additional acceleration and increased brightness in all recorded ranges.
“This is a 40-year-old mystery that we solved, said Yannis Liodakis, lead author of the study and astronomer at FINCA, ESO’s Finnish Center for Astronomy. “Finally, we have all the pieces of the puzzle, and the picture they create is clear.”
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