An international team led by the University of Jaén has identified the first confirmed microblazar in the Milky Way, an astrophysical object that astrophysicists had been searching for over more than three decades. The study also involved researchers from the Institute of Cosmos Sciences of the University of Barcelona (ICCUB), who contributed to the analysis and interpretation of the observations that made it possible to characterize this unique system.
The research, published in Astronomy & Astrophysics, describes the object IRAS 18293−0941, a binary system composed of a massive star and a black hole that ejects jets of matter at speeds close to that of light. One of these jets points almost directly towards Earth, a configuration that makes the system the first confirmed microblazar in our Galaxy.
Blazars are very distant active galactic nuclei that host supermassive black holes with relativistic jets oriented towards the observer. Since the 1990s, theoretical models had predicted the existence of smaller-scale analogues within the Milky Way, known as microblazars. However, until now, no candidate had passed thorough observational verification.
Observations carried out with radio telescopes from the European VLBI Network (EVN), together with data from several international observatories, have confirmed the nature of the system and the orientation of its relativistic jets. Furthermore, the study suggests that the interaction of one of the jets with the interstellar medium could be responsible for accelerating particles to ultra-high energies, linking this object to one of the open questions in modern astrophysics: the origin of the so-called Galactic PeVatrons.
ICCUB contribution
The ICCUB team participated in several key stages of the study. Arnau Aguasca-Cabot contributed to the analysis of data from the Fermi satellite; Daniel del Ser worked on the photometric analysis and the determination of the system’s orbital period; and Josep M. Paredes took part in the observing proposals and in the interpretation of the scientific results.
“The identification of IRAS 18293−0941 as the first confirmed microblazar in the Milky Way represents the culmination of decades of observational research. This discovery not only confirms a long-awaited theoretical prediction, but also provides a unique laboratory for studying particle acceleration mechanisms and the interaction of relativistic jets with the interstellar medium,” highlights Josep M. Paredes.
A new laboratory for high-energy astrophysics
The relative proximity of this system offers an exceptional opportunity to study in detail phenomena that until now had only been observed in much more distant extragalactic objects. Researchers will continue monitoring the system through high-resolution observations and will expand the study of the interaction between the jets and the surrounding molecular cloud in order to better understand the origin of the most energetic particles in our Galaxy.
“This discovery opens the door to studying the particle acceleration processes that take place in the relativistic jets of blazars through an object located approximately one million times closer to us,” says Arnau Aguasca-Cabot, ICCUB-IEEC researcher and co-author of the study.
“Thanks to advanced techniques such as multiband photometry, we have been able to model the variability of the system (an 11.38-day period) despite the severe interstellar obscuration. This analysis also provides an independent geometric confirmation of the microblazar configuration,” explains Daniel del Ser, researcher at the Fabra Observatory-RACAB and co-author of the study.
Reference
A Galactic microblazar as a potential accelerator of ultra-high-energy particles, by Josep Martí Ribas, Pedro Luque-Escamilla, Benito Marcote, L. Abaroa, A. Aguasca-Cabot, J. A. Combi, G. E. Romero, J. M. Paredes, F. García, F. Fogantini, E. A. Saavedra, D. del Ser and J. van den Eijnden, published in Astronomy & Astrophysics.
