Astronomers have discovered the Milky Way’s first stellar-mass black hole microblazar, designated IRAS 18293−0941. Located roughly 12,000 light-years away, the binary system features a compact black hole pulling material from a massive companion star, which it orbits every 11 days, firing near-light-speed particle jets directly toward Earth.
For more than thirty years, researchers suspected such particle-accelerating systems existed in our galaxy, but thick walls of interstellar gas and dust concealed them from standard optical view. The object was initially logged by the Infrared Astronomical Satellite in 1983, yet it languished largely unstudied as astronomers struggled to pierce the cosmic veil.
How Researchers Unmasked IRAS 18293−0941 Using Radio Telescopes and Gaia Data
The breakthrough arrived through a coordinated multi-waveband campaign. Initial radio observations exposed a bright central source paired with a narrow, one-sided jet. Because black holes typically launch twin streams of matter in opposite directions, scientists knew the missing stream was likely traveling directly away from us, making it invisible via direct imaging. The stream pointed toward Earth appears intensely bright due to relativistic beaming.
To confirm that the emission originated from the stellar binary rather than an unrelated background galaxy, the international team turned to high-resolution radio astronomy. By combining data from the European VLBI Network with positional measurements from the European Space Agency’s Gaia spacecraft, the research team pinned down the exact location.
“A one-sided radio jet on its own could always be from a distant galaxy that happens to lie in the same direction of the star we were studying. 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.”
Benito Marcote, Joint Institute for VLBI ERIC, JIVE, in The Netherlands
Optical data subsequently revealed that the black hole and its massive companion star complete an orbit every 11.38 days. Small variations in systemic brightness indicate the binary is viewed almost face-on.
Particle Acceleration and the 100 Light-Year Bubble Detected by MeerKAT
While the opposing jet remains hidden from direct sight, researchers detected its explosive impact using the MeerKAT radio observatory in South Africa. The jet carves out a 100 light-year-wide bubble where it smashes into dense interstellar gas and dust. At the edge of that cavity sits a glowing hotspot where particles reach petaelectronvolt energies.
“None of the individual telescopes could have told the entire story. It’s a great showcase of international teamwork.”
Jakob van den Eijnden, University of Amsterdam
These particles carry roughly 100 times the energy generated by the Large Hadron Collider, establishing stellar-mass microblazars as formidable cosmic particle accelerators. The findings help solve lingering questions about the origins of the galaxy’s most energetic particles and provide a nearby laboratory for studying the physics of distant supermassive black hole blazars.
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