Role of Landau quantization on the neutron-drip transition in magnetar crusts
Role of Landau quantization on the neutron-drip transition in magnetar crusts
复制标题
朗道量子化对磁星地壳中子滴跃转变的作用
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
Ch. J. Velchev
中科院分区：
文献类型：
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作者：
N. Chamel;Zh. K. Stoyanov;L. Mihailov;Y. D. Mutafchieva;R. Pavlov;Ch. J. Velchev
研究了强磁场对磁星地壳中子滴转变的作用。使用 2012 年原子质量评估的实验原子质量测量值，并辅以根据布鲁塞尔-蒙特利尔 Hartree-Fock-Bogoliubov 核质量模型 HFB-24 计算的理论质量，以数字方式确定不同磁场强度的地壳成分和中子滴阈值。发现中子滴点处的平衡核与磁场强度无关。通过分析证明，在电子处于最低朗道能级的强量子化区域，中子滴密度和压力几乎随磁场强度线性增加。对于较弱的磁场，中子滴密度表现出典型的量子振荡。在这种情况下，根据磁场强度，中子滴密度可以增加约 14% 或减少 25%。这些变化被证明几乎是普遍存在的，与所采用的核质量模型无关。这些结果可能对软伽马射线中继器和异常X射线脉冲星中检测到的定时不规则性和准周期振荡的物理解释以及强磁化中子星的冷却具有重要意义。
The role of a strong magnetic field on the neutron-drip transition in the crust of a magnetar is studied. The composition of the crust and the neutron-drip threshold are determined numerically for different magnetic field strengths using the experimental atomic mass measurements from the 2012 Atomic Mass Evaluation complemented with theoretical masses calculated from the Brussels-Montreal Hartree-Fock-Bogoliubov nuclear mass model HFB-24. The equilibrium nucleus at the neutron-drip point is found to be independent of the magnetic field strength. As demonstrated analytically, the neutron-drip density and pressure increase almost linearly with the magnetic field strength in the strongly quantizing regime for which electrons lie in the lowest Landau level. For weaker magnetic fields, the neutron-drip density exhibits typical quantum oscillations. In this case, the neutron-drip density can be either increased by about 14% or decreased by 25% depending on the magnetic field strength. These variations are shown to be almost universal, independently of the nuclear mass model employed. These results may have important implications for the physical interpretation of timing irregularities and quasiperiodic oscillations detected in soft gamma-ray repeaters and anomalous x-ray pulsars, as well as for the cooling of strongly magnetized neutron stars.