A groundbreaking study has unveiled how tidal forces within binary neutron star systems can offer profound insights into the universe's inner workings and the dynamics of these dense stars, as revealed through the analysis of gravitational waves.
University of Illinois Urbana-Champaign physics professor Nicolas Yunes, the study’s lead author, explains that understanding the internal dynamics of neutron stars could not only enhance our grasp of fundamental cosmic processes but also potentially drive future technological advancements.
His research delves into the role of dissipative tidal forces in binary neutron star systems and how these forces illuminate our understanding of the cosmos.
Neutron Star Insights
“Neutron stars are the remnants of massive stars that have undergone gravitational collapse, forming the densest stable objects known in the universe—far denser and colder than anything achievable by particle colliders,” Yunes said, who is also the founding director of the Illinois Center for Advanced Studies of the Universe (ICASU). “Their existence hints at hidden aspects of astrophysics, gravitational theory, and nuclear physics that are essential to comprehending the universe.”
These once-hidden properties of neutron stars became observable through the discovery of gravitational waves, which opened new avenues for exploration.
Gravitational Waves as Cosmic Messengers
“The unique properties of neutron stars are imprinted in the gravitational waves they emit. These waves travel across millions of light-years and can be detected by instruments like the advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo Collaboration,” Yunes explained. “By analyzing these waves, we can infer the stars' internal structure and learn about the extreme physics governing their environments.”
Yunes, a gravitational physicist, sought to explore how tidal forces alter the shape and orbital dynamics of neutron stars, encoding critical information into the gravitational waves they emit. This data could reveal key material properties like internal friction and viscosity, which shed light on out-of-equilibrium processes where energy is transferred in or out of the system.
Breakthrough in Viscosity Research
In their study, Yunes and Illinois researchers Justin Ripley, Abhishek Hegade, and Rohit Chandramouli used simulations, analytical models, and advanced data analysis techniques to examine data from the gravitational wave event GW170817. Although the event was not loud enough to directly measure the stars’ viscosity, the team successfully placed the first observational constraints on the viscosity of neutron stars, marking a significant milestone in the field.
The findings, published in Nature Astronomy, confirm that dissipative tidal forces in binary neutron star systems are detectable through gravitational wave analysis, paving the way for further discoveries.
Legacy and Future Directions
“This represents a major step forward, particularly for ICASU and the University of Illinois,” Yunes remarked. “Illinois has been at the forefront of nuclear physics, especially concerning neutron stars, since the 1970s. With access to data from advanced LIGO and Virgo detectors, and our rich history of nuclear physics expertise, we are well-positioned to continue leading in this domain.”
This study not only reinforces Illinois’ legacy but also opens the door to a deeper understanding of the universe and the physics governing some of its most extreme phenomena.
Sources :
Published 19 July 2024, Nature Astronomy; “A constraint on the dissipative tidal deformability of neutron stars”
DOI: 10.1038/s41550-024-02323-7
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