RX J1856–3754: Evidence for a Stiff Equation of State
RX J1856–3754: Evidence for a Stiff Equation of State
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RX J1856–3754：刚性状态方程的证据
DOI：
10.1086/343895
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
R. Romani
中科院分区：
文献类型：
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作者：
T. Braje;R. Romani
我们研究了附近孤立中子星RX J1856-3754的软X射线加上光学/紫外光谱，并将其与详细的热发射面模型进行了比较。像以前的研究人员一样，我们发现光谱最适合用双温度黑体模型来拟合。此外，我们的模拟从观察到的脉冲分数上限限制了允许的观察几何形状。这些模拟表明，RX J1856-3754很可能是一颗正常的年轻脉冲星，非热射电束偏离了地球的视线。模型参数空间上的光谱能量分布极限对恒星的M/R有很强的制约作用，在测量的视差距离下，MNS=1.5M☉的允许范围为RNS=13.7±0.6公里。在这种解释下，状态方程(EOS)在核密度附近是相对僵硬的，并强烈排除了以前研究中假设的夸克星EOS。这些数据还限制了极帽上的曲面T分布。
We have examined the soft X-ray plus optical/UV spectrum of the nearby isolated neutron star RX J1856-3754, comparing it with detailed models of a thermally emitting surface. Like previous investigators, we find that the spectrum is best fitted by a two-temperature blackbody model. In addition, our simulations constrain the allowed viewing geometry from the observed pulse fraction upper limits. These simulations show that RX J1856-3754 is very likely to be a normal young pulsar, with the nonthermal radio beam missing Earth's line of sight. The spectral energy distribution limits on the model parameter space put a strong constraint on the star's M/R. At the measured parallax distance, the allowed range for MNS = 1.5 M☉ is RNS = 13.7 ± 0.6 km. Under this interpretation, the equation of state (EOS) is relatively stiff near nuclear density, and the quark star EOS posited in some previous studies is strongly excluded. The data also constrain the surface T distribution over the polar cap.