Why some supermassive black holes glow so brightly is explained here.
For the first time, scientists have seen how some supermassive black holes send out shock waves of high-energy particles into space.
Astronomers report November 23 in Nature that shock waves propagating along the jet of one such blazar bend magnetic fields, causing fleeing particles to accelerate to almost the speed of light. Extreme acceleration research can be used to answer basic physics concerns that cannot be addressed in any other way.
From millions or perhaps billions of light-years away, blazars—active black holes that blast jets of high-energy particles toward Earth—appear as bright dots. The exact relationship between the jets’ high speeds and tightly focused columnar beams and the magnetic fields surrounding black holes was unclear to astronomers.
Enter the orbiting telescope called the Imaging X-Ray Polarimetry Explorer (IXPE), which was launched in December 2021. Its objective is to measure the X-ray polarization, or the direction that X-ray radiation is traveling in space. Polarized X-rays can view into a blazar’s active core, in contrast to prior blazar investigations of polarized radio waves and optical light, which explored areas of jets days to years after they had been accelerated.
Astrophysicist Yannis Liodakis of the University of Turku in Finland believes that when using X-rays, “you’re actually looking at the heart of the particle acceleration.” You’re actually focusing on the area where everything occurs.
IPXE observed Markarian 501, a particularly brilliant blazar about 450 million light-years from Earth, in March 2022.
Markarian 501’s jet might be accelerated by magnetic fields in two different ways, according to Liodakis and his coworkers. Magnetic reconnection, in which magnetic field lines break, rebuild, and connect with other neighboring lines, may boost particles. Plasma on the sun is accelerated by the same method (SN: 11/14/19). The polarization of light along the jet should be the same in all wavelengths, from radio waves to X-rays, if it were the particle acceleration engine.
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Another possibility is a shock wave that shoots debris down the jet. The magnetic fields abruptly change from turbulent to organized at the shock location. This switch has the power to shoot off particles like water through a hose nozzle. Turbulence should resume once the particles have left the shock site. Short wavelength X-rays should be more polarized than longer wavelength optical and radio radiation, as determined by other telescopes, if a shock was the cause of the acceleration.
According to Liodakis, the researchers indeed observed that. He claims that the outcome is “obvious” and supports the shock wave theory.
Astrophysicist James Webb of Florida International University in Miami says more research is needed to determine the specifics of the particle movement. One is that it’s unclear what might cause the shock.
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But he adds that “this is a step in the right direction.” “It’s like looking at the object through a new window; we now notice features we hadn’t noticed before. It’s a lot of fun.