论文标题
中子星振子柱中的动力学
Dynamics of Neutron Star Accretion Columns in Split-Monopole Magnetic Fields
论文作者
论文摘要
我们对辐射压力支持的中子恒星积聚柱进行分裂单键型磁场中的辐射压力的2D辐射相对论MHD模拟。积聚柱表现出准周期性振荡，在光度功率谱中表现为2-10 kHz峰，以及更广泛的扩展到较高的频率。峰值频率降低了较宽的色谱柱或更高的质量积聚率。与均匀磁场中较短的色谱柱的情况相反，PDV的工作极大地有助于保持圆柱内部的辐射压力与侧向辐射冷却。这部分是由于沿收敛的磁场线向恒星表面的积聚相关的压缩。在我们所有的模拟中，与慢速扩散光子气泡不稳定性相关的熵波。从振荡本身以及熵波辐射的径向对流对于保持色谱柱内部的辐射压力也很重要。我们的基准模拟积聚的时间平均剖面大致与经典的1D固定模型一致，提供了一个正确的列形状。我们还量化了所有积分柱模拟中的孔隙度，以便原则上也可以用于改善1D模型。
We perform 2D axisymmetric radiative relativistic MHD simulations of radiation pressure supported neutron star accretion columns in split-monopole magnetic fields. The accretion columns exhibit quasi-periodic oscillations, which manifest in the luminosity power spectrum as 2-10 kHz peaks, together with broader extensions to somewhat higher frequencies. The peak frequency decreases for wider columns or higher mass accretion rates. In contrast to the case of shorter columns in uniform magnetic fields, pdV work contributes substantially to maintaining the radiation pressure inside the column against sideways radiative cooling. This is in part due to the compression associated with accretion along the converging magnetic field lines towards the stellar surface. Propagating entropy waves which are associated with the slow-diffusion photon bubble instability form in all our simulations. Radial advection of radiation from the oscillation itself as well as the entropy waves is also important in maintaining radiation pressure inside the column. The time-averaged profile of our fiducial simulation accretion is approximately consistent with the classical 1D stationary model provided one incorporates the correct column shape. We also quantify the porosity in all our accretion column simulations so that this may also in principle be used to improve 1D models.
