Pulse profiles of highly compact pulsars in general relativity
Pulse profiles of highly compact pulsars in general relativity
复制标题
广义相对论中高度致密脉冲星的脉冲轮廓
DOI：
10.1103/physrevd.98.044017
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发表时间：
2018
影响因子：
5
通讯作者：
Miyamoto Umpei
中科院分区：
文献类型：
--
作者：
Sotani Hajime;Miyamoto Umpei
致密恒星的引力光弯曲是一种重要的天体物理现象。弯曲角度取决于恒星的致密性，也就是恒星的乳胶半径之比。在这篇文章中，我们研究了弯曲角超过的高密度旋转中子星的脉冲轮廓。当(恒星模型的弯曲角度等于)时，会发生如此大的弯曲，导致从恒星表面任何位置发射的光子都能到达观察者手中。首先，根据到达观察者的光子路径数，对旋转轴与热点法线之间的倾角和夹角参数平面进行分类。然后，在假设恒星自转不是很快的情况下，我们估计了与磁极帽相关的两个热点从旋转的中子星上发出的光子的随时间变化的通量。结果发现，高致密中子星的脉冲分布与标准中子星的脉冲分布有质的不同。特别是，最大观测通量与最小观测通量之比明显大于标准中子星。这项研究表明，人们可以通过观察脉冲角分布来约束中子星的状态方程，并用其他方法确定。
Gravitational light bending by compact stars is an important astrophysical phenomenon. The bending angle depends on the stellar compactness, which is the ratio of stellar massto radius. In this paper, we investigate the pulse profile of highly compact rotating neutron stars for which the bending angle exceeds. When(the bending angle becomes equal tofor the stellar model with), such a large bending happens, resulting in that a photon emitted from any position on the stellar surface can reach an observer. First, we classify the parameter plane of inclination angleand anglebetween the rotation axis and the normal on the hot spot by the number of photon paths reaching the observer. Then, we estimate the time-dependent flux of photons emitted from two hot spots on the rotating neutron star, associated with the magnetic polar caps, for various combinations ofand, and for two values of compactness, assuming that the stellar rotation is not so fast that the frame dragging and the stellar deformation are negligible. As the result, we find that the pulse profiles of highly compact neutron stars are qualitatively different from those for the standard neutron stars. In particular, the ratio of the maximum observed flux to the minimum one is significantly larger than that for the standard neutron stars. This study suggests that one would be able to constrain the equation of state for neutron stars through the observation of pulse profile with anglesanddetermined by other methods.