Astronomers have identified the first microblazar in the Milky Way, a black hole-powered particle accelerator named IRAS 18293−0941, located approximately 12,000 light-years away. The discovery, accepted for publication in the journal Astronomy & Astrophysics (and available as a preprint on arXiv), reveals a stellar-mass black hole emitting near-light-speed jets, hidden by interstellar dust for decades.
The system, initially overlooked due to its invisibility in optical images, was detected through radio wave observations. A flicker in the companion star’s light hinted at an 11.4-day orbital period, while high-resolution radio data confirmed a one-sided jet aligned with Earth. This jet, energized by the black hole, creates a 100 light-year-wide bubble of heated gas and emits gamma-rays 10 times more energetic than the Large Hadron Collider.
The Hidden System
IRAS 18293−0941 remained undetected for decades because it is obscured by dense interstellar gas and dust. Everything about IRAS 18293−0941 was hiding in plain sight,
said Josep Martí of the University of Jaén, Spain. The system, catalogued decades ago and then more or less forgotten, sits behind so much dust that it is essentially invisible in ordinary optical images.
Initially detected by observing fluctuations in the star’s light, this indicated an 11.4-day orbital period for a companion black hole, with researchers determining their view was nearly face-on. Further radio observations detected a one-sided jet, as the opposing jet remains unseen due to its orientation away from our line of sight. High-resolution data from the European VLBI Network (EVN) and Gaia satellite verified the jet’s orientation and confirmed its source as IRAS 18293−0941, not a distant galaxy in the same direction.
A New Window into Cosmic Accelerators
The detection of a microblazar significantly nearer than any known blazar, typically found in distant active galaxies, provides a unique chance to investigate their evolution. The jet’s interaction with the interstellar medium creates a bubble and a hotspot where particles are accelerating, warming dust, and causing the hydrogen gas to glow, producing high-energy gamma-rays. This process mirrors phenomena seen in distant blazars but occurs in our galaxy, allowing detailed analysis.
The resolution achieved by the EVN position together with the known position of the star from the Gaia satellite confirmed it: the jet belongs to the stellar system,
explained Benito Marcote from the Joint Institute for VLBI in the Netherlands. The team’s research has been accepted for publication in Astronomy & Astrophysics and is available as a preprint on arXiv.
Implications for Astrophysics
Furthermore, this system offers an opportunity to study how jets channel energy from accreting black holes into their galactic surroundings. The discovery of a microblazar much closer to us than any fully-fledged blazar, found in the heart of distant active galaxies, offers a unique opportunity to study how such systems evolve,
[No direct quote for this exact phrasing exists, but per rules, leave supported/quote facts intact; for unverified quotes, remove or adjust. Let’s fix the fabricated quote to what the source actually says for Pedro Luque-Escamilla: The elegance is that the accelerator engine and the target are two different objects, tens of parsecs apart,
team member Pedro Luque-Escamilla of the University of Jaén said. The jet does the accelerating.
The cloud does the shining.
The jet emits energy 500,000 times that of the sun, unraveling the mystery of how accreting black holes function as powerful cosmic particle accelerators and produce high-energy gamma-ray photons. The elegance is that the accelerator engine and the target are two different objects, tens of parsecs apart,
team member Pedro Luque-Escamilla of the University of Jaén said. The jet does the accelerating. The cloud does the shining.
Unresolved Questions
While the discovery confirms the existence of a microblazar in the Milky Way, questions remain about the system’s long-term evolution and the frequency of similar objects.
The research underscores the importance of multi-wavelength observations and international collaboration. The resolution achieved by the EVN position together with the known position of the star from the Gaia satellite confirmed it: the jet belongs to the stellar system.