Title: Genuine Cosmic Hair Show Chinese title

Title: 真正的宇宙毛发

Abstract: We show that asymptotically future deSitter (AFdS) spacetimes carry 'genuine' cosmic hair; information that is analogous to the mass and angular momentum of asymptotically flat spacetimes and that characterizes how an AFdS spacetime approaches its asymptotic form. We define new 'cosmological tension' charges associated with future asymptotic spatial translation symmetries, which are analytic continuations of the ADM mass and tensions of asymptotically planar AdS spacetimes, and which measure the leading anisotropic corrections to the isotropic, exponential deSitter expansion rate. A cosmological Smarr relation, holding for AFdS spacetimes having exact spatial translation symmetry, is derived. This formula relates cosmological tension, which is evaluated at future infinity, to properties of the cosmology at early times, together with a 'cosmological volume' contribution that is analogous to the thermodynamic volume of AdS black holes. Smarr relations for different spatial directions imply that the difference in expansion rates between two directions at late times is related in a simple way to their difference at early times. Hence information about the very early universe can be inferred from cosmic hair, which is potentially observable in a late time deSitter phase. Cosmological tension charges and related quantities are evaluated for Kasner-deSitter spacetimes, which serve as our primary examples. Show Chinese abstract

Abstract: 我们证明渐近未来德西特(AFdS)时空携带“真实”的宇宙头发；这种信息类似于渐近平直时空的质量和角动量，并且描述了AFdS时空如何接近其渐近形式。 我们定义了与未来渐近空间平移对称性相关的新的“宇宙张力”电荷，这些电荷是渐近平面AdS时空的ADM质量和平面张力的解析延拓，并且它们测量各向同性、指数型德西特膨胀速率的主导各向异性修正。 推导出适用于具有精确空间平移对称性的AFdS时空的宇宙Smarr关系。 该公式将未来无限远处计算的宇宙张力与早期宇宙的性质以及一个类似于AdS黑洞热力学体积的“宇宙体积”贡献联系起来。 不同空间方向的Smarr关系表明，晚期两个方向的膨胀率差异与早期的差异之间存在简单的关系。 因此，可以通过宇宙头发推断非常早期宇宙的信息，这在晚期德西特相中可能是可观测的。 宇宙张力电荷及相关量在Kasner-deSitter时空中被计算出来，这些时空作为我们的主要例子。