We systematically examine the crustal torsional oscillations as varying the stellar mass and radius, where we take into account the effect of electron screening due to the inhomogeneity of electron distribution. In the examinations, we adopt two different equations of state (EOSs) for the inner crust region of neutron stars. As a result, we find that the frequencies depend obviously on the EOS, even if the neutron star models are almost independent of the EOS. That is, one could solve the degeneracy of the stellar models with different EOS via the observations of shear oscillations frequencies. Additionally, we find that the fundamental frequencies of the $l$-th order torsional oscillations can reduce 6% due to the effect of electron screening, which is independent of the adopted EOS and stellar models. This reduction of frequencies can be crucial to make a constraints on the density dependence of the nuclear symmetry energy, $L$, i.e., the constraint on $L$ can reduce ~15% by the electron screening effect.
Estimation of neutron star mass and radius of FRB 20240114A by identification of crustal oscillations
Kochi University(高知大学);RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS), RIKEN(理化学研究所交叉理论数学科学中心(iTHEMS));University of Tübingen(蒂宾根大学);University of Maryland, College Park(马里兰大学帕克分校);NASA Goddard Space Flight Center(美国国家航空航天局戈达德太空飞行中心)