An international team of astronomers from ASTRON, JIVE, the University of Amsterdam and other institutions has found the first so-called “microblazar” in the Milky Way. This stellar system is composed of a massive star and a black hole with a jet that is pointed toward Earth. The researchers also identified the region where the jet hits a molecular cloud as a place where particles are accelerated to ultra-high energies, likely up to petaelectronvolts. This would make microblazars one of the most powerful particle accelerators in the galaxy. The research was appears in Astronomy & Astrophysics.
Black holes can attract matter from their surroundings, powering jets of matter and radiation that escape from their poles with extremely high energies. When such a jet is pointed toward Earth, it makes the object appear much brighter. In the case of supermassive black holes—which are found at the center of many galaxies—such blazars have been studied for a long time. Now, for the first time, astronomers have identified a stellar-sized black hole in the Milky Way whose jet is pointed toward Earth. It is the first microblazar found.
Radio imaging has revealed not only the jet but also its interaction with its surroundings. First, the jet crosses a region of about 100 light-years (590 trillion miles), where it has already “cleared” the so-called interstellar medium. After that, it hits a relatively dense molecular cloud, which consists mainly of molecular hydrogen and dust.
The interaction creates a bright spot on the cloud where the interstellar material is ionized and the dust is heated. Here, particles are accelerated to nearly the speed of light, with energies up to petaelectronvolts. This makes the microblazar one of the most powerful particle accelerators in the Milky Way, about 100 times stronger than the Large Hadron Collider, the strongest particle accelerator on Earth.
Microblazars have been predicted for about 30 years. This discovery not only sheds new light on the origins of the most energetic particles in the Milky Way, but it also teaches astronomers about similar but larger systems already found in other galaxies. “This discovery allows us to study remote blazars created by distant supermassive black holes,” says Benito Marcote, senior support scientist at ASTRON and JIVE and one of the paper’s authors. “Those blazars are too remote to be resolved in our images. Having an analog object in our galaxy allows for detailed study of blazar physics.”
Black hole and massive star
The object—IRAS 18293−0941—consists of a black hole about 10 times the mass of our sun and a hot, massive star orbiting each other every 11 days. The jets are produced by matter that the black hole attracts from the star. First, this matter is “collected” in a disk surrounding the black hole. Just before it finally falls into the black hole, part of the matter is ejected through powerful jets at both poles of the black hole.
IRAS 18293−0941 was already cataloged in 1983 by the Dutch-American IRAS satellite. Astronomers’ attention was drawn to the object because, in many radio observations, it appeared to have a bright, compact core and radio emission on one side only, hinting at the existence of such a jet.
An extensive observational campaign was launched using radio telescopes (for high-resolution images and showing jet interactions), optical telescopes (for spectra and measuring velocities in the system), X-ray and gamma-ray telescopes (for probing the hot plasma around the black hole), and infrared images (showing the warm dust around the system). “This was a genuinely multiwavelength observational campaign,” Marcote says.
Elusive particles
Cosmic particles with energies reaching up to petaelectronvolts have been detected by cosmic ray observatories on Earth, but for more than a century, it has remained unclear where these particles are accelerated to such high energies. One candidate accelerator is the shock wave created by a powerful black hole jet hitting the interstellar medium, as seen in the microblazar. In this study, the scientists found that the bright spot in the molecular cloud coincides with a gamma-ray signature of high-energy particles.
Marcote is excited that the microblazar’s jet can be associated with this elusive class of particles. “We are planning more observations of the hot spot where the jet hits the interstellar medium,” Marcote says. “Better characterizing this region and how the material gets heated and ionized would have strong implications for galactic star formation, which happens in molecular clouds. It can also teach us how microblazars affect the structure and evolution of galaxies like the Milky Way.”
“This discovery highlights the power of studying the universe with different kinds of telescopes at the same time, because none of the individual telescopes could have told the entire story,” says co-author Jakob van den Eijnden (University of Amsterdam). “It is a great showcase of the international team effort that is at the core of modern astronomy.”
Publication details
Josep Martí et al, A Galactic microblazar as a potential accelerator of ultra-high-energy particles, Astronomy & Astrophysics (2026). DOI: 10.1051/0004-6361/202661105. On arXiv: arxiv.org/abs/2609.00990
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Milky Way’s first microblazar may produce fastest particles in the galaxy (2026, September 22)
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