Black holes, because of something that can’t be found by light, like to cover themselves in radiance.
As a matter of fact, the most brilliant light in the Universe originates from supermassive black holes. Effectively, those black holes are actually not the black colored holes themselves; It is the material that surrounds them as they intentionally slurp significant amounts of matter from their immediate surroundings.
Galaxies referred to as blazars are among the most brilliant of these maelstroms of warm material. They not only glow with the heat of a swirling coat, they additionally channel material into ‘blazing ‘beams which zoom throughout the cosmos, shedding electromagnetic radiation at energies which can be hard to comprehend.
The mechanism producing the high energy light which gets to us from thousands of years ago has at long last been found out. Shocks increase the speed of particles to incredible velocities in the black hole.
“This is a 40-year-old mystery that we have resolved,’ explains Yannis Liodakis, head of the Finnish Centre for Astronomy at ESO (FINCA). “At last, we had every one of the components of the puzzle, so the picture they made was clear,” he said.
Most galaxies in the Universe are built around a supermassive black hole. These mind- blowingly large objects sit in the galactic center sometimes doing very little (like Sagittarius A *, the black hole at the center of the Milky Way) and quite often a lot.
That task consists of accreting materials. A great cloud builds up to an equatorial disk around the black hole, wrapping it like water around a drain. The frictional and gravitational interactions in severe space within a black hole cause this material to shine and heat brilliantly throughout a variety of wavelengths. That is one source associated with a black hole’s light.
The other – the one at play in blazars – are twin jets of material pushed from the polar regions outside of the black hole, perpendicular to the disk. These planes are thought to be material out of the inner rim of the disk, which gets accelerated along external magnetic field lines to the poles, rather than dropping to the black hole, where it is released at extremely high speeds near the speed of light.
In order for a galaxy to be categorized as a blazar, these jets have to be pointed nearly straight at the viewer. That’s us on Earth. They blaze with light throughout the electromagnetic spectrum thanks to extreme particle acceleration, such as high-energy gamma as well as x rays.
For decades, it has been an enormous cosmic mystery to explain how this jet carries particles at supersonic speeds. But today, a powerful new X ray telescope called the Imaging X ray Polarimetry Explorer (IXPE), launched in December 2021, provided scientists the crucial to resolve the mystery. It’s the first space telescope to find out the orientation or polarization of X rays.
“The first X-Ray polarization measurements of this class of sources permitted an immediate comparison with the models created from observing other light frequencies, from radio to very high-energy gamma rays, for the first time,” claimed Immacolata Donnarumma, of the Italian Space Agency.
IXPE was shifted on the brightest high energy object in our sky, a blazar called Markarian 501, located 460 million light years away in the constellation of Hercules. The telescope retrieved information on X-ray radiation from the blazar’s jet for a total of 6 days in March 2022.
Soon enough, the team noticed an abnormal difference in the X-Ray light. Its orientation was significantly more twisted or polarized compared to lower power wavelengths. Furthermore, optical light was a lot more polarized than radio frequencies.
The direction of polarization, though, was exactly the same for all wavelengths and matched the direction of the jet. This is consistent with models in which shocks create shockwaves in the jets that provide acceleration along the complete length of the jet. This acceleration is at its highest and produces X-radiation close to the shock. Further down the jet line, the particles get rid of power, producing optical and then radio emission with lower polarization.
“As the shock wave crosses the region, the magnetic field becomes stronger and also the energy of the particles gets higher,” Alan Marscher, an astronomer at Boston University, said. “The energy originates from the motion energy of the material that produces the shock wave,” he explained.
It’s not clear what triggers the shocks, but one possible mechanism is faster material in the jet catching up to slower moving clumps, leading to collisions. This particular hypothesis may be confirmed by additional research.
Because blazars are one of the most effective particle accelerators in the Universe and possibly the best labs for extreme physics, this analysis is a critical piece of the puzzle.
Future research will continue to observe Markarian 501 and turn IXPE to other blazars to find out if comparable polarization can be detected.
The research has been published in Nature Astronomy.