NASA’s IXPE helps solve black hole jet mystery

Among the brightest objects within the sky are known as blazars. They include a supermassive black hole feeding off materials swirling round it in a disk, which might create two highly effective jets perpendicular to the disk on both sides. A blazar is very vivid as a result of one in every of its highly effective jets of high-speed particles factors straight at Earth. For many years, scientists have puzzled: How do particles in these jets get accelerated to such excessive energies?

NASA’s Imaging X-Ray Polarimetry Explorer, or IXPE, has helped astronomers get nearer to a solution. In a brand new research within the journal Nature, authored by a big worldwide collaboration, astronomers discover that the most effective rationalization for the particle acceleration is a shock wave throughout the jet.

“It is a 40-year-old thriller that we have solved,” stated Yannis Liodakis, lead writer of the research and astronomer at FINCA, the Finnish Centre for Astronomy with ESO. “We lastly had all the items of the puzzle, and the image they made was clear.”

Launched Dec. 9, 2021, the Earth-orbiting IXPE satellite, a collaboration between NASA and the Italian House Company, gives a particular type of knowledge that has by no means been accessible from space earlier than. This new knowledge contains the measurement of X-ray mild’s polarization, that means IXPE detects the typical route and depth of the electrical subject of sunshine waves that make up X-rays. Details about the electrical subject orientation in X-ray mild, and the extent of polarization, isn’t accessible to telescopes on Earth as a result of the ambiance absorbs X-rays from space.

“The primary X-ray polarization measurements of this class of sources allowed, for the primary time, a direct comparability with the fashions developed from observing different frequencies of sunshine, from radio to very high-energy gamma rays,” stated Immacolata Donnarumma, the mission scientist for IXPE on the Italian House Company. “IXPE will proceed to supply new proof as the present knowledge is analyzed and extra knowledge is acquired sooner or later.”

The brand new research used IXPE to level at Markarian 501, a blazar within the constellation Hercules. This lively black hole system sits on the middle of a big elliptical galaxy.

IXPE watched Markarian 501 for 3 days in early March of 2022, after which once more two weeks later. Throughout these observations, astronomers used different telescopes in space and on the bottom to collect details about the blazar in a variety of wavelengths of sunshine together with radio, optical, and X-ray. Whereas different research have regarded on the polarization of lower-energy mild from blazars prior to now, this was the primary time scientists might get this angle on a blazar’s X-rays, that are emitted nearer to the supply of particle acceleration.

“Including X-ray polarization to our arsenal of radio, infrared, and optical polarization is a recreation changer,” stated Alan Marscher, an astronomer at Boston College who leads the group learning big black holes with IXPE.

Scientists discovered that X-ray mild is extra polarized than optical, which is extra polarized than radio. However the route of the polarized mild was the identical for all of the wavelengths of sunshine noticed and was additionally aligned with the jet’s route.

After evaluating their info with theoretical fashions, the workforce of astronomers realized that the information most carefully matched a state of affairs during which a shock wave accelerates the jet particles. A shock wave is generated when one thing strikes quicker than the pace of sound of the encompassing materials, resembling when a supersonic jet flies by in our Earth’s ambiance.

The research was not designed to analyze the origins of shock waves, that are nonetheless mysterious. However scientists hypothesize {that a} disturbance within the move of the jet causes a piece of it to develop into supersonic. This might end result from high-energy particle collisions throughout the jet, or from abrupt strain modifications on the jet boundary.

“Because the shock wave crosses the area, the magnetic field will get stronger, and vitality of particles will get larger,” Marscher stated. “The vitality comes from the movement vitality of the fabric making the shock wave.”

As particles journey outward, they emit X-rays first as a result of they’re extraordinarily energetic. Shifting farther outward, by way of the turbulent area farther from the situation of the shock, they begin to lose vitality, which causes them to emit less-energetic mild like optical after which radio waves. That is analogous to how the move of water turns into extra turbulent after it encounters a waterfall—however right here, magnetic fields create this turbulence.

Scientists will proceed observing the Markarian 501 blazar to see if the polarization modifications over time. IXPE will even examine a broader assortment of blazars throughout its two-year prime mission, exploring extra longstanding mysteries concerning the universe. “It is a part of humanity’s progress towards understanding nature and all of its exoticness,” Marscher stated.