We have investigated some of the properties of dense sub-nuclear matter at the crustal region (both the outer crust and the inner crust region) of a magnetar. The relativistic version of Thomas-Fermi (TF) model is used in presence of strong quantizing magnetic field for the outer crust matter. The compressed matter in the outer crust, which is a crystal of metallic iron, is replaced by a regular array of spherically symmetric Wigner-Seitz (WS) cells. In the inner crust region, a mixture of iron and heavier neutron rich nuclei along with electrons and free neutrons has been considered. Conventional Harrison-Wheeler (HW) and Bethe-Baym-Pethick (BBP) equation of states are used for the nuclear mass formula. A lot of significant changes in the characteristic properties of dense crustal matter, both at the outer crust and the inner crust, have been observed.
In this work, we have studied oscillations in the crust of a neutron star which magnetic field has both dipolar and toroidal components, the former extends from the stellar interior to the outer space and the later is confined inside the star radius. Our study is based on the solutions we have got for perturbations in the star fluid, confined to the crust thickness. Our results are compared to the frequencies observed in the Soft Gamma Repeaters signals.
We study the symmetry energy and the core-crust transition in neutron stars using the finite-range Gogny nuclear interaction and examine the deduced crustal thickness and crustal moment of inertia. We start by analyzing the second-, fourth- and sixth-order coefficients of the Taylor expansion of the energy per particle in powers of the isospin asymmetry for Gogny forces. These coefficients provide information about the departure of the symmetry energy from the widely used parabolic law. The neutron star core-crust transition is evaluated by looking at the onset of thermodynamical instability o…
Magnetic field evolution in neutron-star crusts is driven by the Hall effect and Ohmic dissipation, for as long as the crust is sufficiently strong to absorb Maxwell stresses exerted by the field and thus make the momentum equation redundant. For the strongest neutron-star fields, however, stresses build to the point of crustal failure, at which point the standard evolution equations are no longer valid. Here, we study the evolution of the magnetic field of the crust up to and beyond crustal failure, whence the crust begins to flow plastically. We perform global axisymmetric evolutions, explor…
Pulsar glitches provide a unique way to study neutron star microphysics because short post-glitch dynamics are directly linked to strong frictional processes on small scales. To illustrate this connection between macroscopic observables and microphysics, we review calculations of vortex interactions focusing on Kelvin wave excitations and determine the corresponding mutual friction strength for realistic microscopic parameters in the inner crust. These density-dependent crustal coupling profiles are combined with a simplified treatment of the core coupling and implemented in a three-component …
In this work, we calculate the neutron anomalous magnetic moment supposing that this value can depend on the density and magnetic field of system. We employ the lowest order constraint variation (LOCV) method and $AV_{18}$ nuclear potential to calculate the medium dependency of the neutron anomalous magnetic moment. It is confirmed that the neutron anomalous magnetic moment increases by increasing the density, while it decreases as the magnetic field grows. The energy and equation of state for the system have also been investigated.
Magneto-elastic oscillations of neutron stars with dipolar magnetic fields
通过二维广义相对论磁流体动力学模拟，我们研究了磁化中子星模型（磁星）的振荡，包括扩展的固体地壳的描述。本研究的目的是了解在SGR的巨型耀斑中观察到的QPO的起源。我们确认了三种不同区域的存在：（a）弱磁场区域B<5 x 10^13 G，地壳剪切模主导演化;（b）中等磁场区域B <5 x 10^13 G<B< 10^15 G，阿尔文类星体主要局限于中子星的核心，地壳剪切模被有效地阻尼;以及（c）强场区B>10^15 G，磁弹性振荡到达表面，接近纯阿尔文准分子轨道。当阿尔文QPO局限于中子星的核心时，我们发现QPO与没有地壳时的QPO性质相似。与偶极磁场配置的闭合场线相关联的较低的QPO被再现为在我们先前的模拟中没有地壳，而连接到开放场线的较高的QPO被从极轴移位。此外，我们观察到一个家庭的边缘QPO。我们的结果没有给SGR巨型耀斑中观测到的QPO留下太多的解释空间，但是可以容纳这样一种解释，即这些观测结果起源于偶极磁场强度在5 x 10^15 G < B < 1.4 x 10^16 G的狭窄范围内的模型中的阿尔文型、全球性、转折点QPO。这个范围比已知磁星的磁场强度估计值稍大。这种差异可以在包括更复杂的磁场结构的模型中解决，或者在考虑核中中子的超流性和质子的超导性的模型中解决。
