Aimed at Earth: the Milky Way’s first microblazar and the galaxy’s fastest particles

Somewhere in our own galaxy, a black hole is firing a jet of matter almost straight at us, and in doing so it may be forging the fastest particles the Milky Way has to offer. Astronomers report the first firmly established «microblazar» in our galaxy, a source called IRAS 18293−0941, whose relativistic jet happens to point nearly along our line of sight. The work, led by Josep Martí of the University of Jaén in Spain, appears in Astronomy & Astrophysics.

What a microblazar actually is

To unpack the name, start big and shrink. A quasar is a supermassive black hole at a galaxy’s heart, devouring matter and launching enormous jets; when one of those jets points almost directly at Earth, we call it a blazar, and it looks especially bright because its light is beamed toward us. Now scale all of that down. A microquasar is the miniature version inside our own galaxy: a stellar-mass black hole, here about ten times the mass of the Sun, pulling gas from a companion star, which in this system circles it roughly every eleven days, and shooting out its own jets. A microblazar, then, is a microquasar whose jet is aimed nearly at us. This is the first one in the Milky Way to be pinned down with solid geometric evidence.

The evidence: a jet with one visible side

The clue is a matter of perspective, and it is worth separating what was seen from what it implies. What the team observed, across many wavelengths, is that the radio jet of IRAS 18293−0941 is collimated and one-sided: we see one beam clearly and its opposite counter-jet barely at all, with a brightness ratio exceeding 26 to 1. What that implies is relativistic beaming, the effect by which a jet racing toward us is brightened and its receding twin dimmed. From that lopsidedness the researchers infer a jet moving at about three-quarters the speed of light, roughly aligned with our sightline. That geometry, plus persistent jets seen over time, is what earns IRAS 18293−0941 the microblazar label, rather than a fleeting candidate.

A natural particle cannon

Here is where it turns extreme. The jet extends some 100 light-years and, crucially, appears to slam into a dense molecular cloud sitting nearby. When a near-light-speed jet crashes into that wall of gas, it can accelerate particles to staggering energies, potentially into the PeV range, that is, around a hundred times the energies reached inside the Large Hadron Collider, humanity’s most powerful accelerator. The proposed mechanism is hadronic: protons in the jet strike the cloud, producing charged pions that decay and unleash a cascade of very-high and ultra-high-energy radiation. Consistent with this, the source sits at the location of a known ultra-high-energy gamma-ray source cataloged as LHAASO J1831−1007u. The authors argue the microblazar is a plausible engine behind it, an interpretation the coincidence supports rather than proves.

Why it matters

The significance reaches beyond one exotic object. For over a century, the origin of the most energetic cosmic rays, subatomic particles that strike Earth’s atmosphere from space, has been an open question, and the search for «PeVatrons,» natural accelerators capable of PeV energies, is one of the hottest pursuits in high-energy astrophysics. Finding a microblazar acting as such an engine right here in the Milky Way would hand physicists a nearby, watchable laboratory for processes usually studied only in distant galaxies. A modest black hole, a doomed companion star, and a jet that happens to point our way may together be running an accelerator no machine on Earth can match, in our own cosmic backyard.

© 2026 Homer Dávila Gutiérrez, FRAS — SKYCR.ORG. All rights reserved. Publication: 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