A deeper knowledge of neutron stars’ mechanisms will enhance our understanding of the universe’s dynamics and potentially stimulate technological advancements. A recent study outlines how insights into dissipative tidal forces in double or binary neutron star systems can enrich our comprehension of the universe.
Enhancing our grasp of neutron stars’ inner workings will not only expand our understanding of the foundational dynamics of the universe, but could also drive advancements in future technologies, as stated by Nicolas Yunes, a physics professor at the University of Illinois Urbana-Champaign. Yunes’ recent study highlights new findings about dissipative tidal forces in binary neutron star systems and what they reveal about the universe.
“Neutron stars are the remnants of collapsed stars and are the densest stable matter found in the universe, existing at densities much higher and temperatures much lower than what particle colliders can produce,” explained Yunes, who is also the founding director of the Illinois Center for Advanced Studies of the Universe. “The existence of neutron stars indicates that there are hidden properties related to astrophysics, gravitational physics, and nuclear physics that are crucial to the universe’s function.”
Many of these previously concealed traits became detectable with the discovery of gravitational waves.
“Neutron stars influence the gravitational waves they emit. These waves travel millions of light-years across space to detectors on Earth, such as the advanced European Laser Interferometer Gravitational-Wave Observatory and the Virgo Collaboration,” Yunes noted. “By capturing and examining these waves, we can deduce neutron stars’ characteristics and gain insights into their internal structures and the extreme physics they experience.”
As a gravitational physicist, Yunes aimed to uncover how gravitational waves carry information about tidal forces that alter the shape of neutron stars and influence their orbital movements. This information might also provide physicists with greater understanding of the stars’ dynamic material qualities, like internal friction or viscosity, “which could shed light on non-equilibrium physical processes leading to the transfer of energy into or out of a system,” Yunes added.
Utilizing data from the gravitational wave incident known as GW170817, Yunes, alongside Illinois researchers Justin Ripley, Abhishek Hegade, and Rohit Chandramouli, employed computer simulations, analytical models, and advanced data analysis techniques to confirm that out-of-equilibrium tidal forces in binary neutron star systems can be detected through gravitational waves. Although the GW170817 event was not significantly intense enough to provide a direct viscosity measurement, Yunes’s team successfully established the first observational limits on the potential viscosity within neutron stars.
The results of the study are published in the journal Nature Astronomy.
“This marks a significant milestone, especially for ICASU and the University of Illinois,” Yunes commented. “In the 1970s, 80s, and 90s, Illinois pioneered numerous leading theories in nuclear physics, particularly those related to neutron stars. This legacy can persist with access to data from the advanced LIGO and Virgo detectors, alongside the collaborations facilitated by ICASU and the established nuclear physics expertise here.”
This research was supported by the University of Illinois Graduate College Dissertation Completion Fellowship and the National Science Foundation.