Stability of neutron stars in Horndeski theories with Gauss-Bonnet couplings
Stability of neutron stars in Horndeski theories with Gauss-Bonnet couplings
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DOI：
10.1103/physrevd.106.064008
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发表时间：
2022-07
影响因子：
5
通讯作者：
Masato Minamitsuji;S. Tsujikawa
中科院分区：
文献类型：
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作者：
Masato Minamitsuji;S. Tsujikawa
在含有Gauss-Bonnet（GB）曲率不变量R2 GB的标量耦合的Horndeski理论中，研究了静态球对称背景下中子星星（NS）解的存在性和线性稳定性.对于形式为α（φ）R 2GB的标量GB耦合，其中是标量场φ的函数，具有非平凡标量轮廓且无不稳定性的线性稳定恒星的存在为无量纲耦合常数的强度提供了上限| α | .为了实现线性（或电子）GB与典型核状态方程耦合的最大质量，我们得到了理论上限（cid：112）。|α GB| < 0。7公里。这比观测含有NS的双星发出的引力波所获得的结果更严格。我们还将三阶标量导数相互作用，四次导数耦合与非最小耦合Ricci标量除了标量GB耦合，并表明NS解决方案与非平凡的标量轮廓满足所有的线性稳定性条件，目前为一定范围内的耦合常数。在从Kaluza-Klein约化得到的正则化四维Einstein-GB引力中，适当地重新调整GB耦合常数，我们发现该理论中的NS来自强耦合问题以及偶宇称扰动的拉普拉斯不稳定性。我们还研究了幂律F（R 2GB）模型中具有非平凡标量分布的NS解，证明了它们在恒星内部是病态的，并且受到鬼不稳定性和恒星外部渐近强耦合问题的困扰.
In Horndeski theories containing a scalar coupling with the Gauss-Bonnet (GB) curvature invariant R 2GB , we study the existence and linear stability of neutron star (NS) solutions on a static and spherically symmetric background. For a scalar-GB coupling of the form αξ ( φ ) R 2GB , where ξ is a function of the scalar field φ , the existence of linearly stable stars with a nontrivial scalar profile without instabilities puts an upper bound on the strength of the dimensionless coupling constant | α | . To realize maximum masses of NSs for a linear (or dilatonic) GB coupling α GB φR 2GB with typical nuclear equations of state, we obtain the theoretical upper limit (cid:112) | α GB | < 0 . 7 km. This is tighter than those obtained by the observations of gravitational waves emitted from binaries containing NSs. We also incorporate cubic-order scalar derivative interactions, quartic derivative couplings with nonminimal couplings to a Ricci scalar besides the scalar-GB coupling and show that NS solutions with a nontrivial scalar profile satisfying all the linear stability conditions are present for certain ranges of the coupling constants. In regularized 4-dimensional Einstein-GB gravity obtained from a Kaluza-Klein reduction with an appropriate rescaling of the GB coupling constant, we find that NSs in this theory suffer from a strong coupling problem as well as Laplacian instability of even-parity perturbations. We also study NS solutions with a nontrivial scalar profile in power-law F ( R 2GB ) models, and show that they are pathological in the interior of stars and plagued by ghost instability together with the asymptotic strong coupling problem in the exterior of stars.