Groundbreaking Discovery: First-Ever X-Ray Emission Detected from Long-Period Radio Transient
In a major breakthrough that redefines our understanding of cosmic radio sources, a multinational team of astrophysicists has reported the first detection of X-ray emission from a long-period radio transient (LPT)—a rare and mysterious class of celestial objects. The findings, published in Nature on May 28, 2025, confirm that LPTs can be far more energetic than previously believed and open a new window into high-energy astrophysics.
The object in question, dubbed ASKAP J1832−0911, was observed to emit both radio and X-ray signals with a synchronized period of 44.2 minutes. The radio signals reached a staggering intensity of 10–20 Jansky, marking it as one of the brightest LPTs ever recorded. Its unusual combination of brightness, periodicity, and dual-wavelength emission sets it apart from all known Galactic sources.
“This is the first time we've caught one of these long-period transients emitting in X-rays,” said Dr. Ziteng Wang, lead author of the study. “It challenges our current models and suggests these objects may be powered by extreme magnetic fields or unknown stellar processes.”
LPTs have puzzled astronomers since their discovery, primarily because their long emission cycles—thousands of times slower than those of typical radio pulsars—don’t conform to established theories of stellar rotation or magnetic activity. Prior models have speculated that LPTs could be ultra-magnetized neutron stars (magnetars), white-dwarf pulsars, or white-dwarf binaries with low-mass companions. However, none had previously shown any sign of X-ray activity—until now.
ASKAP J1832−0911’s synchronized radio and X-ray pulses reveal a class of periodic transients with energy outputs around 10³³ erg/s, suggesting that the engines behind these signals are more powerful than initially imagined. Still, no existing model fully explains the observations. If it is an old magnetar, it must possess unusually persistent activity. If it is a white dwarf, its magnetic field would need to be among the strongest ever theorized.
Co-author Nanda Rea notes that, “Even the most plausible scenarios—such as a decaying magnetar—face serious theoretical roadblocks. This detection pushes us to reconsider what compact stellar remnants are capable of.”
The discovery was made possible through wide-field radio observations from the Australian Square Kilometre Array Pathfinder (ASKAP), paired with follow-up X-ray detections using space-based observatories. The source's detection is expected to drive a new wave of observational campaigns aimed at uncovering similar X-ray-emitting LPTs.
“It’s a game-changer,” commented David Kaplan, another member of the international team. “We’re now looking at a new class of high-energy periodic transients. There’s no telling what else we’ll find.”
The study highlights the importance of multi-wavelength astronomy and sets the stage for future discoveries with the next generation of radio and X-ray observatories.
Reference:
Wang, Z., Rea, N., Bao, T., Kaplan, D. L., Lenc, E., Wadiasingh, Z., Hare, J., Zic, A., Anumarlapudi, A., Bera, A., Beniamini, P., Cooper, A. J., Clarke, T. E., Deller, A. T., Dawson, J. R., Glowacki, M., Hurley-Walker, N., McSweeney, S. J., Polisensky, E. J., . . . Thyagarajan, N. (2025). Detection of X-ray emission from a bright long-period radio transient. Nature. https://doi.org/10.1038/s41586-025-09077-w
