Non-radial oscillation of anisotropic neutron stars in full general relativity

Sushovan Mondal, Manjari Bagchi
General Relativity and Quantum Cosmology, General Relativity and Quantum Cosmology (gr-qc), High Energy Astrophysical Phenomena (astro-ph.HE), Solar and Stellar Astrophysics (astro-ph.SR)
2023-08-31 16:00:00
We investigate non-radial oscillations of anisotropic neutron stars within the framework of general relativity. Our study involves nonrotating, spherically symmetric anisotropic neutron stars as the unperturbed equilibrium configuration. We employ the BSk21 equation of state to describe neutron star matter and introduce a phenomenological ansatz to account for local anisotropy. Through considering small and adiabatic polar perturbations (even parity), we derive oscillation equations from the linearized Einstein equations. Notably, these oscillation equations explicitly incorporate the influence of pressure anisotropy. We calculate the frequencies and damping times of the fundamental (f) mode for various choices of anisotropic pressure strength. Interestingly, we observe that the f-mode frequencies continue to scale linearly with the average density of neutron stars, even in the presence of anisotropy. We conduct a comprehensive analysis of how anisotropy affects both the f-mode frequency and its associated damping time.
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