General Relativity and Quantum Cosmology
New submissions
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New submissions for Thu, 22 Aug 19
 [1] arXiv:1908.07543 [pdf, other]

Title: Some physical implications of regularization ambiguities in SU(2) gaugeinvariant loop quantum cosmologyComments: 29 pages, 9 figuresSubjects: General Relativity and Quantum Cosmology (grqc); Cosmology and Nongalactic Astrophysics (astroph.CO); High Energy Physics  Theory (hepth)
The way physics of loop quantum gravity is affected by the underlying quantization ambiguities is an open question. We address this issue in the context of loop quantum cosmology using gaugecovariant fluxes. Consequences are explored for two choices of regularization parameters: $\mu_0$ and $\bar \mu$ in presence of a positive cosmological constant, and two choices of regularizations of the Hamiltonian constraint in loop quantum cosmology: the standard and the Thiemann regularization. We show that novel features of singularity resolution and bounce, occurring due to gaugecovariant fluxes, exist also for Thiemannregularized dynamics. The $\mu_0$scheme is found to be unviable as in standard loop quantum cosmology when a positive cosmological constant is included. Our investigation brings out a surprising result that the nature of emergent matter in the prebounce regime is determined by the choice of regulator in the Thiemann regularization of the scalar constraint whether or not one uses gaugecovaraint fluxes. Unlike $\bar \mu$scheme where the emergent matter is a cosmological constant, the emergent matter in $\mu_0$scheme behaves as a string gas.
 [2] arXiv:1908.07555 [pdf, ps, other]

Title: Inflationary Phenomenology of Einstein GaussBonnet Gravity Compatible with GW170817Comments: PLB AcceptedSubjects: General Relativity and Quantum Cosmology (grqc); Cosmology and Nongalactic Astrophysics (astroph.CO); High Energy Physics  Theory (hepth)
In this work we shall study Einstein GaussBonnet theories and we investigate when these can have their gravitational wave speed equal to the speed of light, which is unity in natural units, thus becoming compatible with the striking event GW170817. We demonstrate how this is possible and we show that if the scalar coupling to the GaussBonnet invariant is constrained to satisfy a differential equation, the gravitational wave speed becomes equal to one. Accordingly, we investigate the inflationary phenomenology of the resulting restricted Einstein GaussBonnet model, by assuming that the slowroll conditions hold true. As we demonstrate, the compatibility with the observational data coming from the Planck 2018 collaboration, can be achieved, even for a powerlaw potential. We restricted ourselves to the study of the powerlaw potential, due to the lack of analyticity, however more realistic potentials can be used, in this case though the calculations are not easy to be performed analytically. We also pointed out that a stringcorrected extension of the Einstein GaussBonnet model we studied, containing terms of the form $\sim \xi(\phi) G^{ab}\partial_a\phi \partial_b \phi $ can also provide a theory with gravity waves speed $c_T^2=1$ in natural units, if the function $\xi(\phi)$ is appropriately constrained, however in the absence of the GaussBonnet term $\sim \xi(\phi) \mathcal{G}$ the gravity waves speed can never be $c_T^2=1$. Finally, we discuss which extensions of the above models can provide interesting cosmologies, since any combination of $f(R,X,\phi)$ gravities with the above stringcorrected Einstein GaussBonnet models can yield $c_T^2=1$, with $X=\frac{1}{2}\partial_{\mu}\phi\partial^{\mu}\phi $.
 [3] arXiv:1908.07778 [pdf, other]

Title: The cosmological phase space of generalized hybrid metricPalatini theories of gravityComments: 20 pages, 3 figures, 6 tablesSubjects: General Relativity and Quantum Cosmology (grqc); High Energy Physics  Theory (hepth)
In this work, we study the cosmological phase space of the generalized hybrid metricPalatini gravity theory, characterized by the functions $f\left(R,\mathcal R\right)$, using a dynamical system approach. We formulate the propagation equations of the suitable dimensionless variables that describe FLRW universes as an autonomous system. The fixed points are obtained for four different forms of the function $f\left(R,\mathcal R\right)$ and the behavior of the scale factor is computed. We show that due to the structure of the system, no global attractors can be present and also that two different classes of solutions for the scale factor exist. In addition, using a redefinition of the dynamic variables, we also compute solutions for static universes.
 [4] arXiv:1908.07799 [pdf, ps, other]

Title: Sixdimensional MyersPerry rotating black hole cannot be overspunComments: 6 pages, no figuresSubjects: General Relativity and Quantum Cosmology (grqc); High Energy Astrophysical Phenomena (astroph.HE); High Energy Physics  Theory (hepth)
Though under nonlinear accretion, all black holes in four and higher dimensions obey the weak Cosmic Censorship Conjecture, however they generally violate it for the linear test particle accretion with the exception of five dimensional rotating black hole with a single rotation. In dimension greater than five, there exists no extremal condition for black hole with single rotation and hence it can never be overspun. However it does exist for two rotations of five dimensional rotating black hole and then black hole could indeed be overspun under linear accretion. In this paper we study the case of six dimensional rotating black hole with two rotations and show that unlike the five dimensional black hole it cannot be overspun under linear accretion. We would conjecture that so should also be the case in all dimensions greater than six. Thus CCC may always be obeyed for rotating black hole in all dimensions greater than five.
 [5] arXiv:1908.07839 [pdf, ps, other]

Title: Bounding f(R,T) gravity by particle creationComments: Published online: Int. J. Geom. Methods Mod. Phys (2019)Subjects: General Relativity and Quantum Cosmology (grqc)
We consider the possibility of the quantum vacuum states in f(R,T) gravity. Particularly, we study the Bogoliubov transformations associated to different vacuum states for some f(R,T) models. The method consists of fixing the f(R,T) free parameters by requiring the Bogoliubov coefficients to be minimized. In such a way, the particle production is related to the value of the Hubble parameter and also the given f(R,T) model.
 [6] arXiv:1908.07986 [pdf, other]

Title: Glitching pulsars: unraveling the interactions of general relativity with quantum fields in the strong field regimesComments: 19 pages, 11 figures, research articleSubjects: General Relativity and Quantum Cosmology (grqc); High Energy Astrophysical Phenomena (astroph.HE); Nuclear Theory (nuclth)
We present a modification of our previous model for the mechanisms underlying the glitch phenomena in pulsars and young neutron stars. Accordingly, pulsars are born with embryonic cores comprising of purely incompressible superconducting gluonquark superfluid (henceforth SuSucores). As the ambient medium cools and spins down due to emission of magnetic dipole radiation, the mass and size of SuSucores are set to grow discretely with time, in accordance with the OnsagerFeynmann analysis of superfluidity. Presently, we propose that the spacetime embedding glitching pulsars is dynamical and of bimetric nature: inside SuSucores the spacetime must be flat, whereas the surrounding region, where the matter is compressible and dissipative, the spacetime is Schwarzschild. It is further proposed that the topological change of spacetime is derived by the strong nuclear force, whose operating length scales is found to increase with time to reach O(1) cm at the end of the luminous lifetimes of pulsars. The model presented here model is in line with the recent radio and GW observations of pulsars and NSs.
Crosslists for Thu, 22 Aug 19
 [7] arXiv:1908.07780 (crosslist from hepth) [pdf]

Title: Casimir force in the Gödel spacetime and its possible induced cosmological inhomogeneityJournalref: Eur. Phys. J. C (2017) 77:454Subjects: High Energy Physics  Theory (hepth); General Relativity and Quantum Cosmology (grqc)
The Casimir force between two parallel plates in the G\"odel universe is computed for a scalar field at finite temperature. It is observed that when the plates separation is comparable with the scale given by the rotation of the spacetime, the force becomes repulsive and then approaches zero. Since it has been shown previously that the universe may experience a Godel phase for a small period of time, the induced inhomogeneities from the Casimir force are also studied.
 [8] arXiv:1908.07823 (crosslist from physics.classph) [pdf, other]

Title: Sound waves move matterAuthors: Davison E. SoperComments: 6 pages with one figureSubjects: Classical Physics (physics.classph); General Relativity and Quantum Cosmology (grqc); High Energy Physics  Theory (hepth)
A recent Letter has reported that sound waves can carry gravitational mass. I analyze this effect in a Hooke's law solid, considering a wave packet moving in the $z$ direction with an amplitude that is independent of $x$ and $y$. The analysis shows that, at second order in an expansion around small amplitude vibrations, there is a small net motion of material, and thus mass, in the direction opposite to the wave packet propagation. This is a straightforward consequence of Newton's laws.
 [9] arXiv:1908.07892 (crosslist from astroph.CO) [pdf, ps, other]

Title: Parametrizations for tests of gravityAuthors: Lucas LombriserComments: 37 pages; published as part of the IJMPD special issue "Modified Gravity: Progresses and Outlook of Theories, Numerical Techniques and Observational Tests" edited by Baojiu Li and Kazuya KoyamaJournalref: International Journal of Modern Physics D, Vol. 27, No. 15, 1848002 (2018)Subjects: Cosmology and Nongalactic Astrophysics (astroph.CO); General Relativity and Quantum Cosmology (grqc)
With the increasing wealth of highquality astronomical and cosmological data and the manifold departures from General Relativity in principle conceivable, the development of generalized parametrization frameworks that unify gravitational models and cover a wide range of length scales and a variety of observational probes to enable systematic highprecision tests of gravity has been a stimulus for intensive research. A review is presented here for some of the formalisms devised for this purpose, covering the cosmological large and smallscale structures, the astronomical static weakfield regime as well as emission and propagation effects for gravitational waves. This includes linear and nonlinear parametrized postFriedmannian frameworks, effective field theory approaches, the parametrized postNewtonian expansion, the parametrized postEinsteinian formalism as well as an inspiralmergerringdown waveform model among others. Connections between the different formalisms are highlighted where they have been established and a brief outlook is provided for general steps towards a unified global framework for tests of gravity and dark sector models.
Replacements for Thu, 22 Aug 19
 [10] arXiv:1801.03353 (replaced) [pdf, other]

Title: Bohmian quantum gravity and cosmologyComments: 45 pages, 6 figures, PDFLaTeX; written for "Applied Bohmian Mechanics: From Nanoscale Systems to Cosmology", edited by Xavier Oriols Pladevall and Jordi Mompart; v2 typos correctedSubjects: General Relativity and Quantum Cosmology (grqc); Quantum Physics (quantph)
 [11] arXiv:1808.00901 (replaced) [pdf, other]

Title: Measuring the star formation rate with gravitational waves from binary black holesComments: 7 pages, 1 table, 4 figsSubjects: High Energy Astrophysical Phenomena (astroph.HE); General Relativity and Quantum Cosmology (grqc)
 [12] arXiv:1902.00289 (replaced) [pdf, ps, other]

Title: Observational Constraints on Growth Index with CosmographyComments: 14 pages, 4 figures, 5 tables, revtex4; v2: discussions added, Eur. Phys. J. C in press; v3: published versionJournalref: Eur. Phys. J. C 79 (2019) 698Subjects: Cosmology and Nongalactic Astrophysics (astroph.CO); General Relativity and Quantum Cosmology (grqc); High Energy Physics  Theory (hepth)
 [13] arXiv:1902.10716 (replaced) [pdf, ps, other]

Title: Gravitational Radiation from Close Binaries with TimeVarying MassesComments: 6 pages, 1 figure, acceptedSubjects: General Relativity and Quantum Cosmology (grqc); High Energy Astrophysical Phenomena (astroph.HE)
 [14] arXiv:1903.05924 (replaced) [pdf, other]

Title: Prospective constraints on the primordial black hole abundance from the stochastic gravitationalwave backgrounds produced by coalescing events and curvature perturbationsComments: 14 pages, 8 figures. Corrections are included due to updated sensitivity curves of SKA and LISA (which were available when v1 was submitted)Journalref: Phys. Rev. D 99, 103531 (2019)Subjects: Cosmology and Nongalactic Astrophysics (astroph.CO); General Relativity and Quantum Cosmology (grqc); High Energy Physics  Phenomenology (hepph)
 [15] arXiv:1903.09377 (replaced) [pdf, ps, other]

Title: ThreeDimensional Extended Newtonian (Super)GravityComments: 5 pages v3: typos corrected in equations (21), (22) and (24); version appeared in JHEPSubjects: High Energy Physics  Theory (hepth); General Relativity and Quantum Cosmology (grqc)
 [16] arXiv:1903.11211 (replaced) [pdf, ps, other]

Title: Quantum Gravity Made EasyAuthors: John R. KlauderComments: 14 pages, a novel approach to quantizing general relativity, minor corrections; NEW RESULTS, SHARPER EXAMPLES; Important correctionSubjects: General Relativity and Quantum Cosmology (grqc); High Energy Physics  Theory (hepth); Mathematical Physics (mathph); Quantum Physics (quantph)
 [17] arXiv:1904.08912 (replaced) [pdf, other]

Title: AxionDilaton Destabilization and the Hubble TensionComments: v1: 4 pages, 2 figures. v2: references added. v3: more references added, plots updated to show evolution as a function of redshift. v4: Additional references and clarifications added. v5: matches published versionJournalref: Physics Letters B 797 (2019)Subjects: Cosmology and Nongalactic Astrophysics (astroph.CO); General Relativity and Quantum Cosmology (grqc); High Energy Physics  Phenomenology (hepph); High Energy Physics  Theory (hepth)
 [18] arXiv:1904.12390 (replaced) [pdf, other]

Title: Relativistic quantum clocks observe classical and quantum time dilationComments: Minor corrections and updates for clarity, including the normalization of Eq. (42) and plots in Figs. 2 and 3. Comments welcomeSubjects: Quantum Physics (quantph); General Relativity and Quantum Cosmology (grqc)
 [19] arXiv:1905.13019 (replaced) [pdf, other]

Title: Unraveling the origin of black holes from effective spin measurements with LIGOVirgoComments: 22 pages, 10 figuresJournalref: JCAP 1908 (2019) 022Subjects: High Energy Astrophysical Phenomena (astroph.HE); Cosmology and Nongalactic Astrophysics (astroph.CO); General Relativity and Quantum Cosmology (grqc); High Energy Physics  Phenomenology (hepph)
 [20] arXiv:1905.13519 (replaced) [pdf, other]

Title: Charged anisotropic compact star in $f(R,\mathcal{T})$ gravity: A minimal geometric deformation gravitational decoupling approachComments: 18 figures, submitted in JCAPSubjects: General Relativity and Quantum Cosmology (grqc)
 [21] arXiv:1906.08265 (replaced) [pdf, other]

Title: The BTZ black hole violates strong cosmic censorshipComments: 59 pages, 9 figures. Changes in v2: 1) a few discussions added/improved, 2) added Section 5.8 discussing the nonsmoothness of the HartleHawking state at the Cauchy horizonSubjects: High Energy Physics  Theory (hepth); General Relativity and Quantum Cosmology (grqc)
 [22] arXiv:1908.02185 (replaced) [pdf, ps, other]

Title: On the initial geometry of a vacuum cosmological spacetimeAuthors: John LottComments: Some typos corrected. arXiv admin note: text overlap with arXiv:1701.05150Subjects: Differential Geometry (math.DG); General Relativity and Quantum Cosmology (grqc)
 [23] arXiv:1908.03584 (replaced) [pdf, other]

Title: An Optically Targeted Search for Gravitational Waves emitted by CoreCollapse Supernovae during the First and Second Observing Runs of Advanced LIGO and Advanced VirgoAuthors: The LIGO Scientific Collaboration, the Virgo Collaboration: B. P. Abbott, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, K. Ackley, C. Adams, V. B. Adya, C. Affeldt, M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, L. Aiello, A. Ain, P. Ajith, G. Allen, A. Allocca, M. A. Aloy, P. A. Altin, A. Amato, S. Anand, A. Ananyeva, S. B. Anderson, W. G. Anderson, S. V. Angelova, S. Antier, S. Appert, K. Arai, M. C. Araya, J. S. Areeda, M. Arène, N. Arnaud, S. M. Aronson, S. Ascenzi, G. Ashton, S. M. Aston, P. Astone, F. Aubin, P. Aufmuth, K. AultONeal, C. Austin, V. Avendano, A. AvilaAlvarez, S. Babak, P. Bacon, F. Badaracco, M. K. M. Bader, S. Bae, J. Baird, P. T. Baker, F. Baldaccini, G. Ballardin, S. W. Ballmer, A. Bals, S. Banagiri, J. C. Barayoga, C. Barbieri, S. E. Barclay, B. C. Barish, et al. (1136 additional authors not shown)Comments: 13 pages, 5 figuresSubjects: High Energy Astrophysical Phenomena (astroph.HE); General Relativity and Quantum Cosmology (grqc)
 [24] arXiv:1908.03942 (replaced) [pdf, other]

Title: Primordial black holes from sound speed resonance in the inflatoncurvaton mixed scenarioComments: 11 pages, 8 figuresSubjects: Cosmology and Nongalactic Astrophysics (astroph.CO); General Relativity and Quantum Cosmology (grqc); High Energy Physics  Phenomenology (hepph); High Energy Physics  Theory (hepth)
 [25] arXiv:1908.06060 (replaced) [pdf, other]

Title: A gravitationalwave measurement of the Hubble constant following the second observing run of Advanced LIGO and VirgoAuthors: The LIGO Scientific Collaboration, the Virgo Collaboration: B. P. Abbott, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, K. Ackley, C. Adams, R. X. Adhikari, V. B. Adya, C. Affeldt, M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, L. Aiello, A. Ain, P. Ajith, G. Allen, A. Allocca, M. A. Aloy, P. A. Altin, A. Amato, S. Anand, A. Ananyeva, S. B. Anderson, W. G. Anderson, S. V. Angelova, S. Antier, S. Appert, K. Arai, M. C. Araya, J. S. Areeda, M. Arène, N. Arnaud, S. M. Aronson, K. G. Arun, S. Ascenzi, G. Ashton, S. M. Aston, P. Astone, F. Aubin, P. Aufmuth, K. AultONeal, C. Austin, V. Avendano, A. AvilaAlvarez, S. Babak, P. Bacon, F. Badaracco, M. K. M. Bader, S. Bae, J. Baird, P. T. Baker, F. Baldaccini, G. Ballardin, S. W. Ballmer, A. Bals, S. Banagiri, J. C. Barayoga, C. Barbieri, et al. (1127 additional authors not shown)Comments: 19 pages, 6 figuresSubjects: Cosmology and Nongalactic Astrophysics (astroph.CO); General Relativity and Quantum Cosmology (grqc)
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