The Vlasov equation is used to determine the dispersion relation for the eigenmodes of magnetized nuclear and neutral stellar matter, taking into account the anomalous magnetic moment of nucleons. The formalism is applied to the determination of the dynamical spinodal section, a quantity that gives a good estimation of the crust-core transition in neutron stars. We study the effect of strong magnetic fields, of the order of 10 15 -10 17 G, on the extension of the crust of magnetized neutron stars. The dynamical instability region of neutron-proton-electron (npe) matter at subsaturation densities is determined within a relativistic mean-field model. It is shown that a strong magnetic field has a large effect on the instability region, defining the crust-core transition as a succession of stable and unstable regions due to the opening of new Landau levels. The effect of the anomalous magnetic moment is non-negligible for fields larger than 10 15 G. The complexity of the crust at the transition to the core and the increase of the crust thickness may have direct impact on the properties of neutrons stars related with the crust.
We study the effect of strong magnetic fields, of the order of 10 15 -10 17 G, on the extension of the crust of magnetized neutron stars. The dynamical instability region of neutron-proton-electron (npe) matter at subsaturation densities and the mode with the largest growth rate are determined within a relativistic mean-field model. It is shown that the effect of a strong magnetic field on the instability region is very sensitive to the density dependence of the symmetry energy, and that it is at the origin of an increase of the extension of the crust and of the charge content of clusters. DOI: 10.1103/PhysRevC.94.062801 Soft-γ -ray repeaters and some anomalous x-ray pulsars are strongly magnetized neutron stars known as magnetars [1][2][3]. These stars have strong surface magnetic fields of the order of 10 14 -10 15 G [4], and slow rotation with a period of ∼1-12 s. Recently, the time evolution of the magnetic field of isolated x-ray pulsars has been studied by Pons et al. [5]. The authors show that a fast decay of the magnetic field could explain the nonobservation of stars with periods above 12 s. The decay of the magnetic field was obtained by including a high electrical resistivity in the inner crust, attributed to the possible existence of an amorphous and heterogeneous layer at the bottom of the inner crust. The lack of isolated x-ray pulsars with a period higher than 12 s could, therefore, be a direct indication of the existence of an amorphous inner crust, possibly in the form of pasta phases [5].At low nuclear matter densities, a competition between the long-range Coulomb repulsion and short-range nuclear attraction will lead to the formation of clusterized matter, known as nuclear pasta [6], near the crust-core transition. These geometrical configurations are observed not only in nuclear matter, but also in a variety of amorphous solids, crystals, and magnetic and biological materials [7]. One of the main interests of the existence of these exotic structures in the crust of neutron stars is the effect that they might have on the neutrino transport and the subsequent cooling of the neutron star [8].Molecular dynamics simulations of the nuclear pasta have shown that topological defects in the pasta could increase electron scattering and reduce the electrical and the thermal conductivities [9]. Electron conductivity in magnetized neutron star matter was also studied in Ref. [10], and it was shown that the electron transport is strongly anisotropic, due to the presence of strong magnetic fields. The complexity introduced by the magnetic field suggests that both suppression and enhancement of the electron conduction in the presence of the pasta phases are possible, and further calculations are required.* jian-junfang@163.com † pais.lena@gmail.com ‡ sidney.avancini@ufsc.br § cp@teor.fis.uc.pt Stellar matter contains, besides neutrons and protons, also electrons, which neutralize the proton charge. The transition clusterized-homogeneous matter has been estimated by using different methods. In particular, ...
We study the simultaneous effects of the symmetry energy and temperature on the crust-core transition of a magnetar. The dynamical and the thermodynamical spinodals are used to calculate the transition region within a relativistic mean-field approach for the equation of state. Quantizing magnetic fields with intensities in the range of 2 × 10 15 < B < 5 × 10 16 G are considered. Under these strong magnetic fields, the crust extension is very sensitive to the density dependence of the symmetry energy, and the properties that depend on the crust thickness could set a constraint on the equation of state. It is shown that the effect on the extension of the crust-core transition is washed out for temperatures above 10 9 K. However, for temperatures below that value, a noticeable effect exists that grows as the temperature decreases and which should be taken into account when the evolution of magnetars is studied.
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