Researchers at the Curtin node of the International Centre for Radio Astronomy Research (ICRAR) have made a record-breaking astrophysical discovery in astrophysics, unveiling a crucial piece of the puzzle behind the rare and extreme phenomenon known as long-period radio transients.
Led by Associate Professor Natasha Hurley-Walker, along with Csanád Horváth, an undergraduate student at Curtin University, the team discovered a powerful pulse of bright energy emanating from deep space through archival low-frequency data from the Murchison Widefield Array (MWA), a precursor to the highly anticipated Square Kilometre Array Observatory (SKAO). This extraordinary energy pulse, occurring every three hours and lasting between 30 to 60 seconds, represents the longest-period radio transient ever detected, elevating our understanding of the cosmos.
Long-period radio transients are relatively new to science, and the challenge of deciphering how they emit radio waves has perplexed researchers for some time.
With this finding, the researchers believe they may have pinpointed the likely source of the energy burst, offering promising insights into the enigmatic nature of these long radio transients. Unlike other transients identified within our bustling galaxy, where their origins are obscured by surrounding stars, this finding paves the way for deeper exploration and understanding of these rare astrophysical events.
“The long-period transients are very exciting, and for astronomers to understand what they are, we need an optical image. However, when you look toward them, there are so many stars lying in the way that it’s like 2001: A Space Odyssey. ‘My god, it’s full of stars!’” Associate Professor Hurley-Walker explains.
“In a stroke of good fortune, the newly discovered transient, named GLEAM-X J0704-37, was found on the outskirts of our galaxy, in a much emptier region of space in the Puppis constellation, around 5000 light years away.
“Our new discovery lies far off the Galactic Plane, so there are only a handful of stars nearby, and we’re now certain one-star system, in particular, is generating the radio waves.”
The team successfully identified the source of the radio waves to a specific star by utilizing another SKA precursor, the MeerKAT telescope located in South Africa. Following this discovery, they utilized the SOAR observatory in Chile to analyze the star’s spectrum, revealing it to be a low-mass star, specifically an ‘M dwarf.’
This discovery not only raised intriguing questions but also provided clarity on some significant issues. Associate Professor Hurley-Walker explains, “An M dwarf alone couldn’t generate the amount of energy we’re seeing.
“The M dwarfs are low-mass stars that have a mere fraction of the Sun’s mass and luminosity. They constitute 70 percent of the stars in the Milky Way, but not one of them is visible to the naked eye. Our data suggests that it is in a binary with another object, which is likely to be a white dwarf, the stellar core of a dying star. Together, they power radio emission.”
The team is currently focused on conducting follow-up observations that will definitively clarify the nature of the system and provide an explanation for this extreme astrophysical event. A thorough investigation of the MWA archives revealed that GLEAM-X J0704-37 has been active for at least ten years since MWA observations began.
However, it’s possible that this system has been active and yet undiscovered for an even longer period, suggesting that there may be many more such events waiting to be discovered in archives worldwide.
“These long-period radio transients are new scientific discoveries, and the MWA has fundamentally enabled the discoveries,” MWA Director, Professor Steven Tingay, said. “The MWA has a 55-petabyte archive of observations that provide a decade-long record of our Universe.”
“It is like having the data storage equivalent of 55,000 high-end home computers – one of the biggest single collections of science data in the world. It is an absolute gold mine for discovering more phenomena in our Universe, and the data are a playground for astronomers.”
Journal reference:
- N. Hurley-Walker, S. J. McSweeney, A. Bahramian1, N. Rea, C. Horváth1, S. Buchner, A. Williams, B. W. Meyers, Jay Strader, Elias Aydi. A 2.9 hr Periodic Radio Transient with an Optical Counterpart. The Astrophysical Journal Letters, 2024; DOI: 10.3847/2041-8213/ad890e