Low-mass neutron stars: universal relations, the nuclear symmetry energy and gravitational radiation
Low-mass neutron stars: universal relations, the nuclear symmetry energy and gravitational radiation
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DOI：
10.1093/mnras/stw969
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发表时间：
2016-01
影响因子：
4.8
通讯作者：
Hector O. Silva;H. Sotani;E. Berti
中科院分区：
文献类型：
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作者：
Hector O. Silva;H. Sotani;E. Berti
目前测量的最低中子星星质量在1.0 -1.1~M_\odot$范围内，但这些测量要么具有很大的不确定性，要么涉及孤立的中子星。最近Martinez等人[Astrophys. J. 812，143（2015）]表明，低质量中子星可能是引力波探测器的一个有趣的目标。此外，Sotani等人[PTEP 2014，051 E01（2014）]最近发现了将非旋转中子星的质量和表面红移与星星的中心密度和参数$\eta\equiv（K_0 L^2）^{1/3}$联系起来的经验公式，其中K_0是对称核物质的不可压缩性，L是饱和密度下对称能的斜率。出于这些考虑，我们扩展了Sotani等人的工作，缓慢旋转和潮汐变形的中子星。我们计算的惯性矩，四极矩，四极椭圆率，潮汐和旋转勒夫数和近点常数的缓慢旋转的中子星的Hartle-Thorne方程在二阶旋转积分，我们适合所有这些数量的函数的$\eta$和中心密度。这些配合可以用来约束$\eta$，无论是通过观测的电磁波谱中的双星双星，或通过不久的将来观测的引力波谱中的螺旋紧凑双星。
The lowest neutron star masses currently measured are in the range $1.0-1.1~M_\odot$, but these measurement have either large uncertainties or refer to isolated neutron stars. The recent claim of a precisely measured mass $M/M_{\odot} = 1.174 \pm 0.004$ by Martinez et al [Astrophys. J. 812, 143 (2015)] in a double neutron star system suggests that low-mass neutron stars may be an interesting target for gravitational-wave detectors. Furthermore, Sotani et al [PTEP 2014, 051E01 (2014)] recently found empirical formulas relating the mass and surface redshift of nonrotating neutron stars to the star's central density and to the parameter $\eta\equiv (K_0 L^2)^{1/3}$, where $K_0$ is the incompressibility of symmetric nuclear matter and $L$ is the slope of the symmetry energy at saturation density. Motivated by these considerations, we extend the work by Sotani et al to slowly rotating and tidally deformed neutron stars. We compute the moment of inertia, quadrupole moment, quadrupole ellipticity, tidal and rotational Love number and apsidal constant of slowly rotating neutron stars by integrating the Hartle-Thorne equations at second order in rotation, and we fit all of these quantities as functions of $\eta$ and of the central density. These fits may be used to constrain $\eta$, either via observations of binary pulsars in the electromagnetic spectrum, or via near-future observations of inspiralling compact binaries in the gravitational-wave spectrum.