Knowledge of gravitational waves may get a boost from new work on the oscillations in binary neutron stars before merging. These novel vibrations, induced by the interplay between tidal fields of the two stars as they approach each other, were the subject of a recent paper by researchers at the University of Birmingham.
Taking these movements into consideration could make a significant difference to our understanding of the data taken by the Advanced LIGO (Laser Interferometer Gravitational-Wave Observatory) and Virgo instruments. The two tools detect gravitational waves — ripples in time and space — produced by merging black holes and neutron stars.
The researchers’ goal is to have a new model prepared for Advanced LIGO’s next observing run and even more sophisticated models for the next generation of Advanced LIGO instruments, called A+, to begin their first observing run in 2025.
Binary Neutron Star Merger Supranuclear Density Physics
A neutron star merger. Credit: NASA’s Goddard Space Flight Center/CI Lab
The first gravitational waves were detected by the LIGO Scientific Collaboration and Virgo Collaboration in 2016. Since then, scientists have dedicated themselves to progressing their understanding of the massive collisions that create these signals, including the physics of a neutron star at supranuclear densities.
In the supranuclear densities reached in the centre of a neutron star, atomic particles are squeezed together more tightly than in atomic nuclei. The attributes of matter at such extreme densities are among the great unsolved questions of modern science,
“Scientists are now able to get lots of crucial information about neutron stars from the latest gravitational wave detections. Details such as the relationship between the star’s mass and its radius, for example, provide crucial insight into fundamental physics behind neutron stars. If we neglect these additional effects, our understanding of the structure of the neutron star as a whole can become deeply biased,”
said lead-author Dr. Geraint Pratten, of the Institute for Gravitational Wave Astronomy at the University of Birmingham.
“These refinements are really important. Within single neutron stars we can start to understand what’s happening deep inside the star’s core, where matter exists at temperatures and densities we cannot produce in ground-based experiments. At this point we might start to see atoms interacting with each other in ways we have not yet seen — potentially requiring new laws of physics,”
added co-author Dr. Patricia Schmidt, Associate Professor at the Institute for Gravitational Wave Astronomy. Looking ahead, Ph.D. student Natalie Williams is already progressing work on calculations to further refine and calibrate the new models.
The LIGO Virgo collaboration includes two LIGO detectors in the United States, one in Germany, and the Virgo detector in Italy for gravitational wave observations.
Study: Geraint Pratten et al, Impact of Dynamical Tides on the Reconstruction of the Neutron Star Equation of State, Physical Review Letters (2022). DOI: 10.1103/PhysRevLett.129.081102
