2024/01/25 by Anson Ka Long Yip, Yip, Anson Ka Long, Patrick Chi-Kit Cheong +3 · 1 citation
Engineering · Physics and Astronomy · #Astronomical Observations and Instrumentation #FOS: Physical sciences #Geophysics and Sensor Technology #High Energy Astrophysical Phenomena (astro-ph.HE) #Pulsars and Gravitational Waves Research
paper · pdf · doi:10.48550/arxiv.2401.13993
openalex publication_date 2024/01/25 · openalex created_date 2024/01/27 · openalex updated_date 2026/07/28
Violent astrophysical events, including core-collapse supernovae and binary neutron star mergers, can result in rotating neutron stars with diverse degrees of differential rotation. Oscillation modes of these neutron stars could be excited and emit strong gravitational waves. Detecting these modes may provide information about neutron stars, including their structures and dynamics. Hence, dynamical simulations were employed to construct relations for quantifying the oscillation mode frequency in previous studies. Specifically, linear relations for the frequencies of fundamental l=0 quasi-radial mode fF and fundamental l=2 quadrupolar mode f2f were constructed by simulations with the Cowling approximation. Nevertheless, these relations can overestimate fF and underestimate f2f up to ∼ 30%. Furthermore, it has yet to be fully studied how the degree of differential rotation affects fF and f2f. Here, for the first time, we consider both various degrees of differential rotation \TildeA and dynamical spacetime to construct linear relations for quantifying fF and f2f. Through 2D axisymmetric simulations, we first show that both fF and f2f scale almost linearly with the stellar compactness M/R for different values of \TildeA. We also observe the quasi-linear relations for both fF and f2f with the kinetic-to-binding energy ratio T/|W| for different \TildeA values. Finally, we constructed linear fits that can quantify fF and f2f by T/|W|. Consequently, this work updated the relations for the fundamental modes of rotating neutron stars with differential rotations in dynamical spacetime.