Gravitational wave astronomy is expected to provide independent constraints on neutron star properties, such as their dense matter equation of state. This is possible with the measurements of binary components' tidal deformability, which alter the point-particle gravitational waveforms of the late inspiral phase of neutron-star binaries. Although current gravitational wave detectors are not sensitive enough for a precise determination of the individual tidal deformations of the components, a large number of combined observations with future detectors will decrease uncertainties in this quantity. Here we provide a first study of the tidal deformability effects due to the elasticity/solidity of the crust (hadronic phase) in a hybrid neutron star, as well as the influence of a quark-hadronic phase density jump on tidal deformations. We employ the framework of nonradial perturbations with zero frequency and study hadronic phases presenting elastic aspects when perturbed (with the shear modulus approximately $1\%$ of the pressure). We find that the relative tidal deformation change in a hybrid star with a perfect-fluid quark phase and a hadronic phase presenting an elastic part is never larger than about $2-4\%$ (with respect to a perfect-fluid counterpart). These maximum changes occur when the elastic region of a hybrid star is larger than approximately $60\%$ of the star's radius, which may happen when its quark phase is small and the density jump is large enough, or even when a hybrid star has an elastic mixed phase. For other cases, the relative tidal deformation changes due to an elastic crust are negligible ($10^{-5}-10^{-1}\%$), therefore unlikely to be measured even with third generation detectors. Thus, only when the size of the elastic hadronic region of a hybrid star is over half of its radius, the effects of elasticity could have a noticeable impact on tidal deformations.
Role of the crust on the tidal deformability of a neutron star within a unified treatment of dense matter
Institute of Astronomy and Astrophysics, Université Libre de Bruxelles（布鲁塞尔自由大学天文学与天体物理研究所）；LUTH, Observatoire de Paris, PSL Research University, CNRS, Université Paris Diderot, Sorbonne Paris Cité（巴黎天文台宇宙论与天体物理学实验室，巴黎文理研究大学，法国国家科学研究中心，巴黎第七大学，索邦巴黎西岱大学）
Nonradial oscillations of stratified neutron stars with solid crusts: Mode characterization and tidal resonances in coalescing binaries
Max Planck Institute for Gravitational Physics (Albert Einstein Institute)（马克斯·普朗克引力物理研究所（爱因斯坦研究所））；University of Illinois Urbana-Champaign（伊利诺伊大学厄巴纳-香槟分校）；Yangzhou University（扬州大学）；Kyoto University（京都大学）
Magneto-elastic oscillations of neutron stars with dipolar magnetic fields
通过二维广义相对论磁流体动力学模拟，我们研究了磁化中子星模型（磁星）的振荡，包括扩展的固体地壳的描述。本研究的目的是了解在SGR的巨型耀斑中观察到的QPO的起源。我们确认了三种不同区域的存在：（a）弱磁场区域B<5 x 10^13 G，地壳剪切模主导演化;（b）中等磁场区域B <5 x 10^13 G<B< 10^15 G，阿尔文类星体主要局限于中子星的核心，地壳剪切模被有效地阻尼;以及（c）强场区B>10^15 G，磁弹性振荡到达表面，接近纯阿尔文准分子轨道。当阿尔文QPO局限于中子星的核心时，我们发现QPO与没有地壳时的QPO性质相似。与偶极磁场配置的闭合场线相关联的较低的QPO被再现为在我们先前的模拟中没有地壳，而连接到开放场线的较高的QPO被从极轴移位。此外，我们观察到一个家庭的边缘QPO。我们的结果没有给SGR巨型耀斑中观测到的QPO留下太多的解释空间，但是可以容纳这样一种解释，即这些观测结果起源于偶极磁场强度在5 x 10^15 G < B < 1.4 x 10^16 G的狭窄范围内的模型中的阿尔文型、全球性、转折点QPO。这个范围比已知磁星的磁场强度估计值稍大。这种差异可以在包括更复杂的磁场结构的模型中解决，或者在考虑核中中子的超流性和质子的超导性的模型中解决。
General-relativistic treatment of tidal $g$-mode resonances in coalescing binaries of neutron stars. II. As triggers for precursor flares of short gamma-ray bursts
Modelling mountains on accreting magnetized neutron stars
Università di Pisa（比萨大学）；Scuola Normale Superiore（比萨高等师范学院）；Università di Milano（米兰大学）；INFN, Sezione di Milano（意大利国家核物理研究所，米兰分部）；INFN, Sezione di Pisa（意大利国家核物理研究所，比萨分部）；INFN, Sezione di Ferrara（意大利国家核物理研究所，费拉拉分部）；Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences（波兰科学院尼古拉·哥白尼天文学中心）
Maximum elastic deformations of relativistic stars
本文提出了一种计算相对论星最大弹性四极形变的方法，推广了[G. Ushomirsky等人，Mon.没有R. 319，902（2000）]。(We也提出了一种方法，牛顿引力没有考林近似。）我们将这些方法应用于m = 2的四极最相关的引力辐射在三种情况下：地壳变形，变形的强子-夸克混合星的结晶核，和变形的完全结晶色超导夸克星。在所有的情况下，我们发现由于相对论的四极相比，牛顿考林近似，特别是紧凑型恒星的supplies。对于地壳，这些supplies高达~6倍，对于混合星，它们高达~4倍，对于固体夸克星，它们最多为~2倍，而对于低质量星，它们略有增强。我们还探讨了质量和状态方程的范围比以前的工作，并发现，对于某些参数的最大四极杆仍然可以很大。即使在相对论假设下，我们发现1.4太阳质量的恒星可以维持数倍于10^39 g cm ^2（对于SLy状态方程）或接近10^40 g cm ^2（对于产生不太致密恒星的状态方程）的地壳四极。1.4太阳质量的固体夸克星可以维持大约10^44 g cm ^2的四极。混合星通常在1.4太阳质量时没有固体核心，但质量最大的恒星（约2太阳质量）可以维持几倍于1041 g cm ^2的典型微物理参数的四极，以及几倍于1042 g cm ^2的极端参数。所有这些四极杆都假定断裂应变为0.1，并且可以除以10^45 g cm ^2，以得到在别处引用的基准“椭圆率”。
