Machine learning for next-generation gravitational-wave data analysis
Jeff Hazboun, professor of physics, is using artificial intelligence and machine learning to investigate the origins of a recently detected background of gravitational waves that permeates the universe.
Hazboun is part of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), an international collaboration that uses millisecond pulsars — rapidly rotating neutron stars that act as extraordinarily precise cosmic clocks — to detect gravitational waves. By monitoring tiny changes in the arrival times of pulses from dozens of pulsars across the galaxy, researchers can measure distortions in spacetime caused by gravitational waves passing between Earth and the pulsars.
In 2023, NANOGrav reported strong evidence for a long-sought gravitational-wave background, a persistent signal produced by many overlapping sources throughout the universe. While the detection was a major milestone, scientists are still working to determine its origin.
One possibility is that the signal comes from populations of supermassive black hole binaries in distant galaxies. Another is that it originates from exotic processes that occurred shortly after the Big Bang, such as cosmic strings, primordial black holes or phase transitions in the early universe. Distinguishing between these possibilities requires analyzing enormous datasets and evaluating complex astrophysical and cosmological models.
To make those calculations feasible, Hazboun’s group is applying machine learning techniques known as normalizing flows. These neural-network-based methods simplify complicated probability distributions, allowing researchers to explore large parameter spaces far more efficiently than traditional approaches.
The technique dramatically reduces the computational time required to compare competing explanations for the gravitational wave signal. Most importantly, it enables analyses that were previously impractical, including direct statistical comparisons between astrophysical and cosmological models.
As NANOGrav prepares to analyze its upcoming 20-year dataset, Hazboun’s machine-learning tools are helping researchers move closer to answering one of the field’s biggest questions: What is generating the gravitational-wave background that echoes across the universe?