Bold claim: Pulsars’ twinkling is not just pretty; it unlocks the subtle distortions of space itself. Over 10 months, a SETI Institute–led team tracked pulsar PSR J0332+5434 (also known as B0329+54) to map how interstellar gas modulates its radio signal as it travels to Earth. Using the Allen Telescope Array, they gathered data from 900 to 1956 MHz and watched scintillation—the twinkling pattern of the signal—drift gradually over time, revealing slow, meaningful changes.
Pulsars are incredibly dense, rapidly spinning remnants of massive stars that emit highly regular radio pulses. Their precision lets scientists test theories—such as the presence of low-frequency gravitational waves—by timing pulse arrivals with exquisite accuracy. However, interstellar gas can scatter these radio waves, broadening and slightly delaying pulses. Grasping these tiny, shifting delays—sometimes only tens of nanoseconds—helps keep pulsar timing as precise as possible.
Like starlight dimmed by Earth's atmosphere, pulsar signals also scintillate in space. Intervening clouds of electrons cause constructive and destructive interference, creating bright and dim patches across frequencies. These patterns evolve as the pulsar, gas, and Earth move relative to one another, translating to timing delays that vary with the scintillation. By repeatedly monitoring a bright, nearby pulsar, the researchers tracked how these patterns shift and converted them into minute timing corrections—valuable for high-precision pulsar experiments.
“Pulsars are remarkable tools for exploring the universe and our stellar neighborhood,” said Grayce Brown, SETI Institute project leader. “Findings like these improve not only pulsar science but broader astronomy, including SETI efforts.” All radio signals traversing the interstellar medium experience scintillation, and noticeable scintillation can help distinguish human-made interference from genuine extraterrestrial signals.
The study leveraged the ATA’s broad bandwidth and frequent, short session observations. The team measured the scintillation bandwidth—the size of bright regions in the twinkling pattern—nearly daily over roughly 300 days and found clear, time-varying changes on timescales from days to months. There appears to be an overarching long-term variation near ~200 days. The team also introduced a more robust method to estimate how scintillation grows with frequency, taking advantage of the ATA’s wide frequency coverage.
“The Allen Telescope Array is ideally suited for this work,” noted Dr. Sofia Sheikh, co-author and Technosignature Research Scientist at the SETI Institute, highlighting its wide bandwidths and suitability for long-running projects.
These observations illuminate the intricate dance between pulsars, Earth, and the intervening space, aiding scientists in better distinguishing radio-frequency interference from signals that might hint at artificial origins.
The paper is available at doi: 10.3847/1538-4357/ae0fff.
About the SETI Institute
Founded in 1984, the SETI Institute is a nonprofit, multidisciplinary research and education organization whose mission is to lead humanity’s search to understand the origins and prevalence of life and intelligence in the universe and to share that knowledge globally. Its work spans physical and biological sciences, with expertise in data analytics, machine learning, and advanced signal detection technologies. The SETI Institute collaborates with industry, academia, and government agencies, including NASA and the NSF.
Contact: Rebecca McDonald, Director of Communications, SETI Institute.
