论文标题
从核能密度功能理论中吸收中子星。 ii。国家和全球属性方程
Accreting neutron stars from the nuclear energy-density functional theory. II. Equation of state and global properties
论文作者
论文摘要
在低质量X射线二进制的X射线爆发中，物质在中子星的表面上的积聚，其骨灰被埋葬并进一步加工，从而改变了恒星外壳的成分和特性。在系列的第二篇论文中，在核能密度功能理论的框架中研究了增生对状态方程和中子星的全球性质的影响。考虑到由$^{56} $ Fe制成的灰烬，我们使用相同的布鲁塞尔核能密度函数BSK19，BSK20和BSK21计算了状态方程，作为已经在我们以前的研究中用于确定地壳加热的灰烬方程。所有积聚中子星的所有区域均以统一和热力学一致的方式处理。有了这些状态方程，我们确定了增生中子星的质量，半径，惯性矩和潮汐变形性，并与催化的中子恒星相比，基于相同功能的统一状态方程式。在整个地壳中，吸积恒星的状态方程比催化物质的方程明显更硬，其绝热指数$γ\约4/3 $。因此，积聚的中子星的半径较大。但是，如果正确考虑了相邻地壳层之间界面处的密度不连续性，则它们的惯性矩和潮汐变形的能力几乎不会改变。增强中子恒星状态方程的刚度的增强主要是核壳效应的结果，因此确认了我们的第一项研究所强调的量子处理的重要性。通过使用相同功能对地壳加热的先前计算，我们获得了一致的显微镜输入，以模拟中性恒星的模拟。
The accretion of matter onto the surface of a neutron star in a low-mass X-ray binary triggers X-ray bursts, whose ashes are buried and further processed thus altering the composition and the properties of the stellar crust. In this second paper of a series, the impact of accretion on the equation of state and on the global properties of neutron stars is studied in the framework of the nuclear energy-density functional theory. Considering ashes made of $^{56}$Fe, we calculated the equations of state using the same Brussels-Montreal nuclear energy-density functionals BSk19, BSk20, and BSk21, as those already employed for determining the crustal heating in our previous study for the same ashes. All regions of accreting neutron stars were treated in a unified and thermodynamically consistent way. With these equations of state, we determined the mass, radius, moment of inertia, and tidal deformability of accreted neutron stars and compared with catalyzed neutron stars for which unified equations of state based on the same functionals are available. The equation of state of accreted neutron stars is found to be significantly stiffer than that of catalyzed matter, with an adiabatic index $Γ\approx 4/3$ throughout the crust. For this reason, accreting neutron stars have larger radii. However, their crustal moment of inertia and their tidal deformability are hardly changed provided density discontinuities at the interface between adjacent crustal layers are properly taken into account. The enhancement of the stiffness of the equation of state of accreting neutron stars is mainly a consequence of nuclear shell effects, thus confirming the importance of a quantum treatment as stressed in our first study. With our previous calculations of crustal heating using the same functionals, we have thus obtained consistent microscopic inputs for simulations of accreting neutron stars.
