Large and massive neutron stars: Implications for the sound speed within QCD of dense matter
Large and massive neutron stars: Implications for the sound speed within QCD of dense matter
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DOI：
10.1103/physrevc.105.035808
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发表时间：
2021-10
影响因子：
3.1
通讯作者：
C. Drischler;Sophia Han;S. Reddy
中科院分区：
文献类型：
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作者：
C. Drischler;Sophia Han;S. Reddy
美国宇航局的NICER望远镜最近测量了已知的两个太阳质量中子星中最重的PSR J 0740 +6620的X射线辐射。数据分析[米勒等人，占星术。J. Lett. 918，L28（2021）; Riley等人，占星术。J. Lett. 918，L27（2021）]表明PSR J 0740 +6620在68%可信度水平下的半径范围为R2.0 <$（11.4− 16.1）km。在这篇文章中，我们研究了这种分析的影响，在高密度内核中的声速，通过使用最近的手征有效场理论（χEFT）计算的状态方程在次tonext-next-to-leading order描述外部区域的星星在适度的密度。我们发现，在内核，min{cs，max}的最大声速的下限，迅速增加与大质量中子星的半径。如果χEFT仍然是核相互作用的有效展开，直到大约两倍的核饱和密度，R2.0 > 13 km分别需要在68%和95%的可信度水平下的min{cs，max} > 0.562和0.442。
The NASA telescope NICER has recently measured x-ray emissions from the heaviest of the precisely known two-solar mass neutron stars, PSR J0740+6620. Analysis of the data [Miller et al., Astrophys. J. Lett. 918, L28 (2021); Riley et al., Astrophys. J. Lett. 918, L27 (2021)] suggests that PSR J0740+6620 has a radius in the range of R2.0 ≈ (11.4− 16.1) km at the 68% credibility level. In this article, we study the implications of this analysis for the sound speed in the high-density inner cores by using recent chiral effective field theory (χEFT) calculations of the equation of state at next-tonext-to-next-to-leading order to describe outer regions of the star at modest density. We find that the lower bound on the maximum speed of sound in the inner core, min{cs,max}, increases rapidly with the radius of massive neutron stars. If χEFT remains an efficient expansion for nuclear interactions up to about twice the nuclear saturation density, R2.0 > 13 km requires min{cs,max} > 0.562 and 0.442 at the 68% and 95% credibility level, respectively.