Gravitational waves have been directly detected and astronomical observations indicate that our Universe has a positive cosmological constant $Λ$. Nevertheless, a theoretical gauge-invariant notion of gravitational waves arriving at infinity (escaping from the space-time) in the presence of a positive $Λ$ has been elusive. We find the answer to this long-standing gravitational puzzle and present a geometric, gauge-invariant radiation condition at infinity.
Matching conditions at null infinity in the presence of logarithms: the role of advanced and retarded radiation
Facultad de Ingeniería, Universidad San Sebastián（圣塞巴斯蒂安大学工程学院）；Université Libre de Bruxelles（布鲁塞尔自由大学）；International Solvay Institutes（国际索尔维研究所）；Collège de France, Université PSL（法兰西公学院，巴黎文理研究大学）；Centro de Estudios Científicos (CECs)（科学研究中心）；Erwin Schrödinger Int. Institute for Mathematics and Physics, University of Vienna（维也纳大学埃尔温·薛定谔数学与物理国际研究所）
A novel criterion to determine the presence of gravitational radiation arriving to, or departing from, null infinity of any weakly asymptotically-simple space-time with vanishing cosmological constant is given. The quantities involved are geometric, of tidal nature, with good gauge behaviour and univocally defined at null infinity. The relationship with the classical characterisation using the News tensor is analysed in detail. A new balance law at infinity is presented, which may be useful to define `radiation states'.
Combinatorial quantum gravity is governed by a discrete Einstein-Hilbert action formulated on an ensemble of random graphs. There is strong evidence for a second-order quantum phase transition separating a random phase at strong coupling from an ordered, geometric phase at weak coupling. Here we derive the picture of space-time that emerges in the geometric phase, given such a continuous phase transition. In the geometric phase, ground-state graphs are discretizations of Riemannian, negative-curvature Cartan-Hadamard manifolds. On such manifolds, diffusion is ballistic. Asymptotically, diffusi…
The existence of gravitational radiation arriving at null infinity -- i.e. escaping from the physical system -- is addressed in the presence of a non-negative cosmological constant $Λ\geq 0$. The case with vanishing $Λ$ is well understood and relies on the properties of the News tensor field (or the News function) defined at infinity. The situation is drastically different when $Λ>0$ where there is no known notion of `News' with similar good properties. In this paper both situations are considered jointly from a {\em tidal} point of view, that is, taking into account the strength (or energy) o…
Carroll-Cotton Tensors and Gravitational Radiation at Null Infinity
École polytechnique, Centre National de la Recherche Scientifique – Unité Mixte de Recherche 7644, Institut Polytechnique de Paris（巴黎综合理工学院，法国国家科学研究中心联合研究单位7644，巴黎理工学院）；Université Libre de Bruxelles and International Solvay Institutes（布鲁塞尔自由大学和国际索尔维研究所）；International School for Advanced Studies (SISSA)（高级国际研究学院（SISSA））；Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Trieste（意大利国家核物理研究所的里雅斯特分部）；Université de Mons（蒙斯大学）
The spacetime inside the white hole is like an anisotropic cosmological background with the past singularity playing the role of a big bang singularity. The scale factor along the extended spatial direction is contracting while the scale factor along the two-sphere is expanding. We consider an eternal Schwarzschild manifold and study quantum cosmological perturbations generated near the white hole singularity which propagate towards the past event horizon and to exterior of the black hole. It is shown that an observer deep inside the white hole and an observer far outside the black hole both s…
I describe the Schwarzian behavior of the gravitational field at null infinity under superrotations, to be understood as an \textit{unobservable} gauge artifact. To this end I review the induced geometry of null infinity and the construction of the gauge-invariant News tensor that characterizes gravitational radiation. I discuss potentially important implications for the celestial holography program, suggesting in particular that the uplift of the AdS$_3$/CFT$_2$ correspondence directly relates to the unobservable gauge sector.
We apply the Bogoliubov transformations in order to connect two different vacuums, one~located at past infinity and another located at future infinity around a black hole inside the scenario of the nonlinear theory of massive gravity. The presence of the extra degrees of freedom changes the behavior of the logarithmic singularity and, as a consequence, the relation between the two Bogoliubov coefficients. This has an effect on the number of particles, or equivalently, on the black hole temperature perceived by observers defining the time arbitrarily.
We obtain the second-order asymptotics for the radiation field of spherically symmetric solutions to the wave equation on spherically symmetric and asymptotically flat backgrounds including the Schwarzschild and sub-extremal Reissner-Nordstrom families of black holes. These terms appear as logarithmic corrections to the leading-order asymptotic terms which were rigorously derived in our previous work. Such corrections were heuristically and numerically derived in the physics literature in the case of a non-vanishing Newman-Penrose constant. In this case, our results provide a rigorous confirma…
Reply to "Comment on 'Quantization of FRW spacetimes in the presence of a cosmological constant and radiation'"
爱茉莉的评论{ \it et al.} [gr-qc/0611029]包含了对我们最近的一篇论文[Phys. Rev. D { \bf 73}，044022（2006）]中报道的结果的数值精度的有效批评，以及关于如何表征量子宇宙学奇点的新想法。然而，我们认为，与评论中所建议的相反，我们研究的量子宇宙学模型几乎没有表现出任何奇异行为的迹象。
In this work, we investigate the Hawking radiation in higher dimensional Reissner-Nordström black holes as received by an observer, resides at infinity. The frequency-dependent transmission rates, which deform the thermal radiation emitted in the vicinity of the black hole horizon, are evaluated numerically. Apart from the case of four-dimensional spacetime, the calculations are extended to higher dimensional Reissner-Nordström metrics, and the results are found to be somewhat sensitive to the spacetime dimension. In general, it is observed that the transmission coefficients practically vanish…
We consider solutions to the Einstein-massless-scalar field system with a positive cosmological constant, arising from sufficiently regular, near-FLRW, initial data. We establish global existence in the future direction and derive their precise asymptotic behavior towards infinity. As a corollary, we infer that, unlike the FLRW background, the perturbed solutions do not describe a regular irrotational stiff fluid with linear equation of state $p=ρ$, for general asymptotic data at infinity. The reason for the breakdown of this interpretation is that the gradient of the scalar field stops being …
Generation of primordial cosmological density inhomogeneities with scale invariant power spectrum during the standard radiation dominated expansion of the universe
