Researchers propose a theoretical model that explains the interior of a blazar, the most powerful source of radiation in the Universe

José María Martí and Manel Perucho,  s and researchers at the Department of Astr
José María Martí and Manel Perucho, s and researchers at the Department of Astronomy and Astrophysics of the University of Valencia.

University of Valencia researchers propose a theoretical model that explains the interior of a blazar, the most powerful source of radiation in the Universe

José María Martí and Manel Perucho, researchers at the University of Valencia, are the authors of the theoretical model that has made it possible to interpret the image with the highest resolution and sensitivity ever achieved of a blazar, the jet of matter that emerges from the nucleus of a galaxy, in this case 3C 279, at a speed close to that of light. In the article published in the journal Nature Astronomy, the research led by the Instituto de Astrofísica de Andalucía (IAA-CSIC) shows large helical filaments at the base of the blazar, a fact that according to the Valencian researchers -required an alternative model to the one used for four decades to explain variations in the intensity of radiation-.

Blazars are the most powerful sources of continuous radiation in the Universe. Like the rest of active galaxies, they show a structure formed by a central supermassive black hole surrounded by a disk of matter that feeds it. They are part of the 10% of active galaxies that show a jet of matter that emerges from the two poles of the system at very high speed, and they are among the even smaller percentage of cases in which their orientation allows us to observe the jet head-on. Now, a group of researchers led by the Instituto de Astrofísica de Andalucía (IAA-CSIC) has observed the jet of the galaxy 3C 279 and found helical filaments with a double helix structure.

"The properties of the helical filaments allow us to conclude that they originate from instabilities in the plasma of which the jets are formed", points out Manel Perucho (UV), professor in the Department of Astronomy and Astrophysics. "Adding all the ingredients, we found that the model used for four decades to explain the radio variability associated with jets does not work in this case, which is why we propose an alternative model to explain it, which takes into account the observed structures with spatial interferometry", adds José María Martí, professor of Astronomy and Astrophysics at the UV.

According to Antonio Fuentes, the IAA researcher who leads the work, this observation has been possible thanks to RadioAstron, a radio telescope in orbit capable of covering distances close to the Moon, and to a network of twenty-three radio telescopes spread across the whole planet. The result of the research reveals that the jet of 3C 279 shows a complex structure formed by at least two helical filaments that extend from near the core to beyond 570 light-years away. This is a never-before-observed structure, and it extends a previous result: in 2020, the Event Horizon Telescope (EHT), which obtained the first image of a black hole in 2019, revealed structures unexpected in the nucleus of 3C 279, although the sensitivity provided by the EHT was insufficient to observe the filaments.

In addition, the study indicates the presence of a helical magnetic field that confines the jet. It would, therefore, be the magnetic field, which in 3C 279 rotates clockwise around the jet, which would channel the material traveling around it at a speed of 0.997 times that of light.

"This result, along with other recent ones, suggests that blazar jets have a complex and rich internal structure, beyond the morphologies in the form of how they are observed in lower resolution studies. Our results open the door to the reinterpretation and revision of many other sources of this type, and highlight the importance of new global networks of radio telescopes that achieve greater angular resolution and sensitivity, such as the Next Generation EHT in the next decade and, in the longer term, space missions that operate in millimetre wavelengths", concludes José Luis Gómez (IAA-CSIC), co-