Key facts
- Astronomers found a trail of cool molecular gas indicating that jets from microquasar LMC P3 power its unusually strong gamma-ray emission.
- LMC P3 is one of only a few known microquasars located outside the Milky Way.
- The molecular gas trail is straight and narrow, spanning about 26 light-years by three light-years.
- The gas in the trail measures 35 to 60 kelvin, while surrounding gas is 15 kelvin.
Astronomers have found a trail of cool molecular gas in the Large Magellanic Cloud, indicating that the high-speed particle jets from microquasar LMC P3 — a scaled-down quasar powered by a stellar-mass black hole or neutron star — are what drive the system’s unusually strong gamma-ray output, in research published in 2026 in The Astrophysical Journal Letters. The discovery addresses a puzzle about LMC P3 that has persisted since the system was first found.
The system came to light in 2016 as a binary star pair sending out unusually strong gamma rays, and it now stands as the most luminous gamma-ray binary star system. LMC P3 pairs a compact object that may be a black hole or neutron star with a massive star weighing more than 30 solar masses. The two stars orbit each other roughly every 10 days, and LMC P3 sits within DEM L241, a supernova remnant and molecular gas cloud left behind by the explosion that formed its compact object.
LMC P3 ranks among just a handful of known microquasars found beyond the Milky Way. Its home in the Large Magellanic Cloud gives astronomers a clear, dust-free line of sight to such rare systems, since dust within our own galaxy blocks views toward the Milky Way’s core. Unlike the dusty core of our galaxy, this cloud does not block views with dust, making LMC P3 easier to study despite lying outside our galaxy.
Starting in 2022, researchers from Nagoya University and Gifu University in Japan used the ALMA observatory in Chile to study DEM L241 and LMC P3. ALMA ranks among the world’s largest radio telescopes. The team studied cold molecular gas using carbon monoxide observations gathered through ALMA bands 6 and 7, captured at wavelengths near 1.3 mm and 0.87 mm, measurements that let them determine the gas’s shape, movement, and temperature.
The molecular gas trail forms a straight, narrow feature spanning about 26 light-years by three light-years. Gas within the trail measures 35 to 60 kelvin, while surrounding gas measures 15 kelvin, making the trail much hotter than the material around it and helping it stand out. The study describes the feature as a trail of heated molecular gas, although the material remains cold compared with everyday temperatures.
Yasuo Fukui, professor emeritus at Nagoya University and lead author, said the elevated temperature across most of the molecular cloud points to interaction with a powerful jet coming from the compact object. “We discovered a gigantic molecular jet,” Fukui said. He added that such a jet is capable of producing the system’s gamma-ray output. Fukui leads the discovery published in The Astrophysical Journal Letters under DOI 10.3847/2041-8213/aea0cb.
Fukui also said that because black holes generate more powerful jets than neutron stars, the system’s intense gamma-ray output strongly suggests its central object is a black hole rather than a neutron star. He added that the finding “provides a very strong support for the possibility that its central object is a black hole.”
The study backs jet-driven molecular gas as one of two rival explanations for LMC P3’s gamma-ray emission. A microquasar represents a scaled-down quasar, powered by a stellar-mass black hole or neutron star rather than a supermassive black hole. In this system, a compact object could pull material from its companion into an accretion disk, forming a microquasar that launches high-speed particle jets able to generate gamma rays.
The competing pulsar wind model calls for a fast-spinning neutron star whose outflow of particles slams into the companion star’s stellar wind, building a shock that drives particles to gamma-ray energies. Radio waves supplied the key clue to the LMC P3 puzzle, and gamma rays sit at the extreme high end of the electromagnetic spectrum.
The research was co-led by Bhuvana Gadikere Rajendra and Kisetsu Tsuge of Gifu University’s Institute for Advanced Study, along with Hidetoshi Sano of Gifu University’s Graduate School of Natural Science and Technology. These scholars back the microquasar-jets explanation for LMC P3’s gamma rays.
The full author list includes Yasuo Fukui, Bhuvana G. R, Hidetoshi Sano, Kisetsu Tsuge, Rami Z.E. Alsaberi, Rin Yamada, Yuya Asano, Aya Bamba, Miroslav Filipovic, Charles Law, Norikazu Mizuno, Toshikazu Onishi, Paul Plucinsky, Gavin Rowell, Manami Sasaki, Piyush Sharda, Hiromasa Suzuki, Kengo Tachihara, Kazuki Tokuda, and Yumiko Yamane. Nagoya University and Gifu University authors on the paper include Fukui, Rajendra, Sano, Tsuge, Alsaberi, Yamada, Asano, Tachihara, and Yamane.
The observations drew on ALMA data set ADS/JAO.ALMA #2021.2.00008.S. Funding included JSPS KAKENHI grants 25K17435, 21H01136, and 24H00246; the Tokai Pathways to Global Excellence program; MEXT Strategic Professional Development Program for Young Researchers; fellowship JPMJFS2138; and NASA Hubble Fellowship grant HST-HF2-51535.001-A.
Grant 25K17435 supported Kisetsu Tsuge, while grants 21H01136 and 24H00246 supported Hidetoshi Sano. The Tokai Pathways to Global Excellence program, part of Japan’s MEXT Strategic Professional Development Program for Young Researchers, and fellowship JPMJFS2138 provided further backing. NASA supported Charles Law through Hubble Fellowship grant No. HST-HF2-51535.001-A, awarded by the Space Telescope Science Institute for NASA under contract NAS5-26555.
Join the discussion