# General Relativity and Quantum Cosmology

## New submissions

[ total of 28 entries: 1-28 ]
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### New submissions for Fri, 22 Jun 18

[1]
Title: Black hole binaries: ergoregions, photon surfaces, wave scattering, and quasinormal modes
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Theory (hep-th); Fluid Dynamics (physics.flu-dyn)

The photon surface of isolated black holes is related to important aspects of black hole physics, such as strong lensing, absorption cross section of null particles and the way that black holes relax through quasinormal ringing. When two black holes are present -- such as during the inspiral and merger events of interest for gravitational-wave detectors -- the concept of a photon surface still exists, but its properties are basically unknown. With these applications in mind, we study here the photon surface of two different static black hole binaries. The first one is the Majumdar-Papapetrou geometry describing two extremal, charged black holes in equilibrium, while the second one is the double sink solution of fluid dynamics, which describes (in a curved-spacetime language) two "dumb" holes. For the latter solution, we also characterize its dynamical response to external perturbations, and study how it relates to the photon surface structure. In addition, we compute the ergoregion of such spacetime and show that it does not coincide with the event horizon.

[2]
Title: Structure of Correlated Worldline Theories of Quantum Gravity
Subjects: General Relativity and Quantum Cosmology (gr-qc); Quantum Physics (quant-ph)

We consider the general form of "Correlated Worldline" (CWL) theories of quantum gravity. We show that one can have 2 different kinds of CWL theory, in which the generating functional is written as either a sum or a product over multiple copies of the coupled matter and gravitational fields. In both versions, the paths in a functional formulation are correlated via gravity itself, causing a breakdown of the superposition principle; however, the product form survives consistency tests not satisfied by the summed form. To better understand the structure of these two theories, we show how to perform diagrammatic expansions in the gravitational coupling for each version of CWL theory, using particle propagation and scalar fields as examples. We explicitly calculate contributions to 2-point and 4-point functions, again for each version of the theory, up to 2nd-order in the gravitational coupling.

[3]
Title: Gravity in Extreme Regions Based on Noncommutative Quantization of Teleparallel Gravity
Subjects: General Relativity and Quantum Cosmology (gr-qc)

In this paper, a noncommutative gravitational theory is constructed by applying Moyal deformation quantization and the Seiberg-Witten map to teleparallel gravity, a classical gravitational theory, as a gauge theory of local translational symmetry. Since our model is based on teleparallel gravity, it is an extremely simple noncommutative gravitational theory. We also clearly divide the role of the products, such that the metric is responsible for the rule of the inner product (which is calculated by taking the sum over the subscripts) and the Moyal product is responsible for tensor and field noncommutativity. This solves problems related to the order of the products and the relationship between the metric and the Moyal product. Furthermore, we analyze the cosmic evolution of the very early universe and the spacetime features around black holes using the constructed noncommutative gravitational theory, and find that gravity acts repulsively in the extreme region where its quantum effects become prominent.

[4]
Authors: Bahram Mashhoon
Comments: 18 pages, invited contribution to appear in "Relativistic Geodesy: Foundations and Applications", D. Puetzfeld et al. (eds.), 2018
Subjects: General Relativity and Quantum Cosmology (gr-qc)

Gravity gradiometry within the framework of the general theory of relativity involves the measurement of the elements of the relativistic tidal matrix, which is theoretically obtained via the projection of the spacetime curvature tensor upon the nonrotating orthonormal tetrad frame of a geodesic observer. The behavior of the measured components of the curvature tensor under Lorentz boosts is briefly described in connection with the existence of certain special tidal directions. Relativistic gravity gradiometry in the exterior gravitational field of a rotating mass is discussed and a gravitomagnetic beat effect along an inclined spherical geodesic orbit is elucidated.

[5]
Title: On the quantum equivalence of an antisymmetric tensor field with spontaneous Lorentz violation
Subjects: General Relativity and Quantum Cosmology (gr-qc)

We consider a minimal model of rank-2 antisymmetric field with spontaneous Lorentz violation, and obtain a classically equivalent Lagrangian consisting of vector field. The 1-loop effective actions of both theories have been derived, and compared to check their quantum equivalence. We find that the spontaneous Lorentz violating terms disturb the structure of effective action in each of these theories. In flat spacetime, it has been shown that for a given choice of vacuum expectation value of antisymmetric field, the two Lagrangians in consideration are not equivalent at the quantum level.

[6]
Title: Cosmological solutions from multi-measure model with inflaton field
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)

In a recent work, we have demonstrated that the two-measures model in which one modifies gravity so that a scalar field is coupled to both standard Riemannian metric and to another non-Riemannian volume form is compatible with observational data from Supernovae type Ia.
As a continuation of this work, in current article we numerically investigate the influence of an additional inflaton scalar field with a step like effective potential. We succeeded to reproduce the Universe inflation epoch, matter dominated epoch and present accelerating expansion in a seamless way. An interesting feature is that during the evolution the inflaton field undergoes a finite change.

[7]
Title: Explicit black hole solutions in higher-derivative gravity
Comments: 5 pages, 3 figures: accepted for publication as a Rapid Communication in Physical Review D
Subjects: General Relativity and Quantum Cosmology (gr-qc)

We present, in an explicit form, the metric for all spherically symmetric Schwarzschild-Bach black holes in Einstein-Weyl theory. In addition to the black hole mass, this complete family of spacetimes involves a parameter that encodes the value of the Bach tensor on the horizon. When this additional "non-Schwarzschild parameter" is set to zero the Bach tensor vanishes everywhere and the "Schwa-Bach" solution reduces to the standard Schwarzschild metric of general relativity. Compared with previous studies, which were mainly based on numerical integration of a complicated form of field equations, the new form of the metric enables us to easily investigate geometrical and physical properties of these black holes, such as specific tidal effects on test particles, caused by the presence of the Bach tensor, as well as fundamental thermodynamical quantities.

[8]
Title: On the causal structure of black holes in shift-symmetric Horndeski theories
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)

In theories with derivative (self-)interactions, the propagation of perturbations on non-trivial field configurations is determined by effective metrics. Generalized scalar-tensor theories belong in this class and this implies that the matter fields and gravitational perturbations do not necessarily experience the same causal structure. Motivated by this, we make a first step in exploring the causal structure of black holes as perceived by scalar fields in the Horndeski class. We consider linearised perturbations on a fixed background metric that describes a generic black hole. The effective metric that determines the propagation of these perturbation does not generally coincide with the background metric (to which matter fields couple minimally). Assuming that the metric and the scalar respect stationarity and that the surface gravity of the horizon is constant, we prove that Killing horizons of the background metric are always Killing horizons of the effective metric as well. Hence, scalar perturbation cannot escape the region that matter fields perceive as the interior of the black hole. This result does not depend on asymptotics but only on local considerations and does not make any reference to no-hair theorems. We also demonstrate that, when one relaxes the stationarity assumption for the scalar, solutions where the horizons of the effective and the background metrics do not match can be found in the decoupling limit.

[9]
Title: Equations of motion of self-gravitating $N$-body systems in the first post-Minkowskian approximation
Subjects: General Relativity and Quantum Cosmology (gr-qc)

We revisit the problem of the equations of motion of a system of $N$ self-interacting massive particles (without spins) in the first post-Minkowskian (1PM) approximation of general relativity. We write the equations of motion, gravitational field and associated conserved integrals of the motion in a form suitable for comparison with recently published post-Newtonian (PN) results at the 4PN order. We show that the Lagrangian associated with the equations of motion in harmonic coordinates is a generalized one, and compute all the terms linear in $G$ up to 5PN order. We discuss the Hamiltonian in the frame of the center of mass and exhibit a canonical transformation connecting it to previous results directly obtained with the Hamiltonian formalism of general relativity. Finally we recover the known result for the gravitational scattering angle of two particles at the 1PM order.

### Cross-lists for Fri, 22 Jun 18

[10]  arXiv:1806.07910 (cross-list from hep-th) [pdf, ps, other]
Title: Black hole thermodynamics with the cosmological constant as independent variable: Bridge between the enthalpy and the Euclidean path integral approaches
Subjects: High Energy Physics - Theory (hep-th); General Relativity and Quantum Cosmology (gr-qc)

Viewing the cosmological constant $\Lambda<0$ as an independent variable, we consider the thermodynamics of the Schwarzschild black hole in an anti-de Sitter (AdS) background. For this system, there is one approach which regards the enthalpy as the master thermodynamic variable and makes sense if one considers the vacuum pressure due to the cosmological constant acting in the volume inside the horizon and the outer size of the system is not restricted. From this approach a first law of thermodynamics emerges naturally. There is yet another approach based on the Euclidean action principle and its path integral that puts the black hole inside a cavity, defines a quasilocal energy at the cavity's boundary, and from which a first law of thermodynamics in a different version also emerges naturally. The first approach has affinities with critical phenomena in condensed matter physics and the second approach is an ingredient necessary for the construction of quantum gravity. The bridge between the two approaches is carried out rigorously, putting thus the enthalpic thermodynamics with $\Lambda$ as independent variable on the same footing as the quasilocal energy approach.

[11]  arXiv:1806.08052 (cross-list from astro-ph.CO) [pdf, ps, other]
Title: Exact solutions of primordial gravitational waves
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)

The future detection projects of gravitational waves are expected to have the sensitivity of detecting the primordial gravitational waves, which may be useful to get new insight into the very early universe. It is essential to analyze the evolution equation of the gravitational waves to estimate the present field strength of the primordial gravitational waves. In this paper, we obtain analytic solutions of the gravitational wave equation in the presence of non-relativistic matters as well as the cosmological constant. Although it is difficult to obtain the solution directly, we find that the equation for the square of the amplitudes has a simple polynomial solution. This quantity, which is directly related to the energy density of the gravitational waves, turns out to be useful to construct analytic solutions for the amplitudes by using Weierstrass's elliptic functions.

[12]  arXiv:1806.08178 (cross-list from astro-ph.CO) [pdf, other]
Title: Non-Gaussian Features of Primordial Gravitational Waves
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)

We explore possible non-Gaussian features of primordial gravitational waves by constructing model-independent templates for nonlinearity parameters of tensor bispectrum. Our analysis is based on Effective Field Theory of inflation that relies on no particular model as such and thus the results are quite generic. The analysis further reveals that chances of detecting squeezed limit tensor bispectrum are fairly higher than equilateral limit. We also show that by tuning practically one parameter, namely the speed of propagation of primordial gravitational waves, one can have considerably large tensor non-Gaussianities that may be of interest to upcoming CMB missions.

[13]  arXiv:1806.08300 (cross-list from astro-ph.CO) [pdf, other]
Title: A precise extragalactic test of General Relativity
Comments: Published in Science. 42 pages, 10 figures including supplementary text and figures
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA); General Relativity and Quantum Cosmology (gr-qc)

Einstein's theory of gravity, General Relativity, has been precisely tested on Solar System scales, but the long-range nature of gravity is still poorly constrained. The nearby strong gravitational lens, ESO 325-G004, provides a laboratory to probe the weak-field regime of gravity and measure the spatial curvature generated per unit mass, $\gamma$. By reconstructing the observed light profile of the lensed arcs and the observed spatially resolved stellar kinematics with a single self-consistent model, we conclude that $\gamma = 0.97 \pm 0.09$ at 68% confidence. Our result is consistent with the prediction of 1 from General Relativity and provides a strong extragalactic constraint on the weak-field metric of gravity.

[14]  arXiv:1806.08348 (cross-list from math.DG) [pdf, other]
Title: Smoothing the Bartnik boundary conditions and other results on Bartnik's quasi-local mass
Subjects: Differential Geometry (math.DG); General Relativity and Quantum Cosmology (gr-qc)

Quite a number of distinct versions of Bartnik's definition of quasi-local mass appear in the literature, and it is not a priori clear that any of them produce the same value in general. In this paper we make progress on reconciling these definitions. The source of discrepancies is two-fold: the choice of boundary conditions (of which there are three variants) and the non-degeneracy or "no-horizon" condition (at least six variants). To address the boundary conditions, we show that given a 3-dimensional region $\Omega$ of nonnegative scalar curvature ($R \geq 0$) extended in a Lipschitz fashion across $\partial \Omega$ to an asymptotically flat 3-manifold with $R \geq 0$ (also holding distributionally along $\partial \Omega$), there exists a smoothing, arbitrarily small in $C^0$ norm, such that $R \geq 0$ and the geometry of $\Omega$ are preserved, and the ADM mass changes only by a small amount. With this we are able to show that the three boundary conditions yield equivalent Bartnik masses for two reasonable non-degeneracy conditions. We also discuss subtleties pertaining to the various non-degeneracy conditions and produce a nontrivial inequality between a no-horizon version of the Bartnik mass and Bray's replacement of this with the outward-minimizing condition.

### Replacements for Fri, 22 Jun 18

[15]  arXiv:1707.09578 (replaced) [pdf, other]
Title: Primordial black holes and second order gravitational waves from ultra-slow-roll inflation
Comments: add the discussion of second order gravitational waves, accepted for publication in JCAP
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
[16]  arXiv:1709.01943 (replaced) [pdf, other]
Title: Explaining LIGO's observations via isolated binary evolution with natal kicks
Authors: D. Wysocki (1), D. Gerosa (2), R. O'Shaughnessy (1), K. Belczynski (3), W. Gladysz (4), E. Berti (5,6), M. Kesden (7), D. Holz (8) ((1) Rochester Institute of Technology, (2) Caltech, (3) Nicolaus Copernicus Astronomical Centre, Warsaw, (4) Warsaw University, (5) University of Mississippi, (6) CENTRA)
Comments: 19 pages, 14 figures, as published in PRD
Journal-ref: Phys. Rev. D 97, 043014 (2018)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
[17]  arXiv:1711.09625 (replaced) [pdf, ps, other]
Title: Hawking Radiation in the Spacetime of White Holes
Authors: Kimet Jusufi
Journal-ref: Gen. Relativ. Gravit. 50, 84 (2018)
Subjects: General Relativity and Quantum Cosmology (gr-qc)
[18]  arXiv:1712.08603 (replaced) [pdf, other]
Title: Gravitational waves from spinning binary black holes at the leading post-Newtonian orders at all orders in spin
Comments: 16 pages, 1 figure; updated to match published version
Journal-ref: Phys. Rev. D 97, 124046 (2018)
Subjects: General Relativity and Quantum Cosmology (gr-qc)
[19]  arXiv:1712.08783 (replaced) [pdf, ps, other]
Title: Universality in the stress tensor for Holographic fluids at the finite cutoff surface via fluid/gravity correspondence
Subjects: High Energy Physics - Theory (hep-th); General Relativity and Quantum Cosmology (gr-qc)
[20]  arXiv:1801.03012 (replaced) [pdf, ps, other]
Title: Microscopic origin of de Sitter entropy
Comments: 6 pages; misspellings fixed, thanks to David Brahms
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
[21]  arXiv:1802.00177 (replaced) [pdf, ps, other]
Title: Black Hole Entropy production and Transport coefficients in Lovelock Gravity
Comments: 8 pages, no figures, expanded version accepted for publication in PRD
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
[22]  arXiv:1803.01722 (replaced) [pdf, other]
Title: Distortion of the standard cosmology in R+R^2 theory
Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[23]  arXiv:1803.06330 (replaced) [pdf, other]
Title: Interior metric and ray-tracing map in the firework black-to-white hole transition
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
[24]  arXiv:1803.11120 (replaced) [pdf, other]
Title: Hyperbolic vortices and Dirac fields in 2+1 dimensions
Comments: 27 pages, 5 figures, J Phys A accepted version
Subjects: High Energy Physics - Theory (hep-th); General Relativity and Quantum Cosmology (gr-qc); Mathematical Physics (math-ph)
[25]  arXiv:1804.08249 (replaced) [pdf, ps, other]
Title: Improving the absolute accuracy of the gravitational wave detectors by combining the photon pressure and gravity field calibrators
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
[26]  arXiv:1805.08773 (replaced) [pdf, other]
Title: Exploring compensated isocurvature perturbations with CMB spectral distortion anisotropies
Comments: 26 pages, 4 figures; v2: numerical calculation corrected, constraints changed
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
[27]  arXiv:1806.02334 (replaced) [pdf]
Title: A Gravitational Wave Transmitter