An international research team has identified IRAS 18293-0941, a dust-obscured binary star system located roughly 12,000 light-years from Earth, as a compelling galactic microblazar candidate. The system features a stellar-mass black hole shooting out a plasma jet at speeds exceeding two-thirds of the speed of light roughly toward our line of sight, offering astronomers a nearby laboratory to study extreme particle acceleration previously observed only in distant extragalactic blazars millions or billions of light-years away.
Discovery of a Galactic Microblazar Candidate
Astronomers have long predicted the existence of a galactic microblazar—a binary system containing a black hole or neutron star pulling gas from a companion and launching narrow plasma jets where relativistic Doppler boosting brightens the approaching stream. However, previous candidates failed closer examination.
Lead author Josep Martí of the Universidad de Jaén in Spain noted that the object was cataloged decades ago and largely forgotten because thick interstellar dust renders it practically invisible in standard optical images. Radio observations managed to bypass the dust barrier. According to Benito Marcote of the Joint Institute for VLBI ERIC in the Netherlands, archival data and an eight-hour observation using the European VLBI Network (EVN) confirmed the jet belongs to the stellar system rather than a distant background active galaxy by matching its radio position to data from the European Space Agency’s Gaia satellite.
Relativistic Jets and Binary Orbit Measurements
Data from the Very Large Array and the European VLBI Network tracked a continuous, one-sided jet spanning from small scales to a distant radio patch. The approaching jet is at least 26 times brighter than any trace of its receding counterpart, requiring gas moving faster than two-thirds of the speed of light within roughly 48 degrees of our line of sight. Optical monitoring via Spanish telescopes and the Zwicky Transient Facility revealed a recurring brightness variation of 0.02 magnitudes every 11.38 days, matching the orbital period of the system.
Spectroscopic data from Calar Alto point to a hot, massive giant or supergiant companion shedding gas at speeds between 300 and 400 kilometers per second into a dusty envelope. The system’s modeled black hole is estimated at roughly 10 solar masses, feeding at a rapid pace while the orbit’s inferred 20-degree tilt ensures the jet points near Earth.
Did you know? While extragalactic blazars are powered by supermassive black holes weighing millions to billions of suns—such as Markarian 421 located 400 million light-years away—IRAS 18293-0941 is driven by a black hole modeled to roughly 10 solar masses situated inside the Milky Way.
Particle Acceleration at the Jet Collision Site
While the jet pointing toward Earth spreads into a wide, faint bubble in thin gas, the opposing jet remains narrow until it crashes into a dense molecular cloud tens of parsecs away. Radio images from South Africa’s MeerKAT array reveal a compact hot spot surrounded by glowing hydrogen and warm dust at this shock front. Carbon monoxide surveys place a large molecular cloud along the line of sight at a distance of 3.6 kiloparsecs, establishing the 12,000-light-year distance.
This hot spot overlaps with LHAASO J1831-1007u*, a source of gamma rays exceeding 100 teraelectronvolts detected by China’s Large High Altitude Air Shower Observatory. Co-author Pedro Luque-Escamilla of the Universidad de Jaén explained that the accelerator engine and the target are two separate objects sitting tens of parsecs apart, where protons accelerated by the jet collide with gas in the cloud to produce gamma rays.
Frequently Asked Questions About IRAS 18293-0941
What is a microblazar?
A microblazar is a microquasar where a black hole or neutron star feeds on a companion star and launches a relativistic jet pointed nearly directly at Earth. Doppler boosting makes the approaching jet appear significantly brighter, mirroring the mechanics of supermassive blazars found in distant galaxies.
How far away is IRAS 18293-0941?
Researchers estimate the distance at approximately 3.6 kiloparsecs, or about 12,000 light-years, based on the molecular cloud impacted by the system’s jet.
How does a microblazar differ from a standard microquasar?
A microblazar is a microquasar whose jet points near our line of sight, creating the amplified luminosity and observational characteristics associated with distant blazars.
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