Blazars and Their Smaller Cousins
Imagine a supermassive black hole, millions of times the mass of our sun, sitting at the heart of a distant galaxy. As it greedily pulls in surrounding gas and dust, it doesn't swallow everything. Instead, it launches twin jets of particles and radiation
from its poles at nearly the speed of light. When one of these ferocious jets happens to be pointed directly at Earth, the galaxy appears incredibly bright. Astronomers call this spectacular phenomenon a 'blazar'. For years, they theorised that a smaller version should exist within our own Milky Way. This would be a 'microquasar'—a regular, stellar-mass black hole (perhaps just 10 times the sun's mass) doing the same thing on a smaller scale. If its jet were pointed at us, it would be dubbed a 'microblazar'.
A 30-Year Hunt for a Cosmic Phantom
The concept of a microblazar has been a tantalising prediction for over 30 years, but finding one proved to be incredibly difficult. While several candidates emerged over the years, none survived close scrutiny. The newest contender, however, looks extremely promising. The system, known as IRAS 18293-0941, was first catalogued in 1983 but was largely forgotten, hidden behind a thick veil of interstellar dust that makes it invisible to normal optical telescopes. Located about 12,000 light-years away, it consists of a black hole roughly 10 times the mass of the sun, locked in an 11-day orbit with a massive companion star from which it strips material to power its jets.
The Evidence for a Microblazar
An international team of scientists revived interest in IRAS 18293-0941 after spotting tell-tale signs in radio surveys. Using a combination of powerful radio telescopes, including the European VLBI Network (EVN), they observed a bright, one-sided jet—a classic sign of 'relativistic beaming', where a jet moving towards an observer at near-light speed appears far brighter than the one moving away. The jet is travelling at an astonishing 75% of the speed of light. Crucially, by combining their data with precise location information from the Gaia satellite, the team confirmed the jet was coming from the star system itself, and not from a distant background galaxy. This solidified its status as the strongest microblazar candidate found to date.
A Cosmic Laboratory in Our Galaxy
The discovery of IRAS 18293-0941 is more than just ticking a box on a cosmic scavenger hunt. Blazars are billions of light-years away, making it impossible to study the regions where their jets are born. A microblazar in our own galaxy provides an unparalleled close-up view of this extreme process. Because it is so much smaller, its changes happen on much faster timescales, allowing astronomers to watch events unfold that would take centuries in a normal blazar. This 'cosmic laboratory' can help answer fundamental questions about how black holes of all sizes launch such powerful jets.
Solving a High-Energy Mystery?
There's another intriguing piece of the puzzle. The microblazar appears to be located near a known 'hotspot' of unexplained ultra-high-energy gamma rays. The research team suggests this might not be a coincidence. While one jet points towards Earth, its opposite number, pointing away from us, is likely smashing into a dense cloud of interstellar gas. This collision could act as a colossal natural particle accelerator, creating the very high-energy particles detected in that region—energies far greater than anything achievable at the Large Hadron Collider on Earth. If confirmed, this would help solve the long-standing mystery of where some of our galaxy's most energetic cosmic rays originate.
