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On the electromagnetic constitutive laws that are equivalent to spacetime metrics 

submitted by kosoore 19 minutes ago  Topic: Geography 

The raising of both indices in the components of the Minkowskielectromagnetic field strength 2form to give the components of theelectromagnetic excitation bivector field can be regarded as being equivalentto an electromagnetic constitutive law, as well as being defined by thecomponents of the spacetime metric. This notion is clarified, and the nature ofthe equivalent dielectric tensors and mag...



Conserved Quantities of harmonic asymptotic initial data sets 

submitted by kosoore 19 minutes ago  Topic: Geography 

In the first half of this article, we survey the new quasilocal and totalangular momentum and center of mass defined in [9] and summarize the importantproperties of these definitions. To compute these conserved quantities involvessolving a nonlinear PDE system (the optimal isometric embedding equation),which is rather difficult in general. We found a large family of initial datasets on which s...



A short note on the curvature perturbation at second order 

submitted by kosoore 19 minutes ago  Topic: Geography 

Working with perturbations about an FLRW spacetime, we compute thegaugeinvariant curvature perturbation to second order solely in terms ofscalar field fluctuations. Using the curvature perturbation on uniform densityhypersurfaces as our starting point, we give our results in terms of fieldfluctuations in the flat gauge, incorporating both large and small scalebehaviour. For ease of future nume...



Connecting horizon pixels and interior voxels of a black hole 

submitted by kosoore 19 minutes ago  Topic: Geography 

In this paper we discuss to what extent one can infer details of the interiorstructure of a black hole based on its horizon. Recalling that black holethermal properties are connected to the nonclassical nature of gravity, wecircumvent the restrictions of the no hair theorem by postulating that theblack hole interior is singularity free due to violations of the usual energyconditions. Further t...



Tests of General relativity with planetary orbits and Monte Carlo simulations 

submitted by kosoore 19 minutes ago  Topic: Geography 

Based on the new developped planetary ephemerides INPOP13c, determinations ofacceptable intervals of General Relativity violation in consideringsimultaneously the PPN parameters $beta$, PPN $gamma$, the flattening of thesun $J_{2}^odot$ and time variation of the gravitational mass of the sun $mu$are obtained in using Monte Carlo simulation coupled with basic geneticalgorithm. Possible time vari...



Nonlinear Spinor Fields in Bianchi typeI spacetime: Problems and Possibilities 

submitted by kosoore 19 minutes ago  Topic: Geography 

Within the scope of Bianchi typeI cosmological model we study the role ofspinor field in the evolution of the Universe. It is found that due to thespinor affine connections the energy momentum tensor of the spinor becomesnondiagonal, whereas the Einstein tensor is diagonal. This nontriviality ofnondiagonal components of the energymomentum tensor imposes some severerestrictions either on th...



Cauchy problem as a twosurface based `geometrodynamics' 

submitted by kosoore 19 minutes ago  Topic: Geography 

Fourdimensional spacetimes foliated by a twoparameter family of homologoustwosurfaces are considered in Einstein's theory of gravity. By combining a1+(1+2) decomposition, the canonical form of the spacetime metric and asuitable specification of the conformal structure of the foliating twosurfacesa gauge fixing is introduced. It is shown that, in terms of the chosengeometrically distinguishe...



A New Approach to Cosmological Bulk Viscosity 

submitted by kosoore 19 minutes ago  Topic: Geography 

We examine the cosmological consequences of an alternative to the standardexpression for bulk viscosity, one which was proposed to avoid the propagationof superluminal signals without the necessity of extending the space ofvariables of the theory. The Friedmann equation is derived for this case, alongwith an expression for the effective pressure. We find solutions for theevolution of the densit...



Orthogonal BipoSH measures : Scrutinizing sources of isotropy violation 

submitted by kosoore 19 minutes ago  Topic: Geography 

The two point correlation function of the CMB temperature anisotropies isgenerally assumed to be statistically isotropic (SI). Deviations from thisassumption could be traced to physical or observational artefacts andsystematic effects. Measurement of nonvanishing power in the BipoSH spectra isa standard statistical technique to search for isotropy violations. Althoughthis is a neat tool allowi...



Intermediate scalings in holographic RG flows and conductivities 

submitted by kosoore 19 minutes ago  Topic: Geography 

We construct numerically finite density domainwall solutions whichinterpolate between two $AdS_4$ fixed points and exhibit an intermediate regimeof hyperscaling violation, with or without Lifshitz scaling. Such RG flows canbe realized in gravitational models containing a dilatonic scalar and a massivevector field with appropriate choices of the scalar potential and couplings. The infrared $AdS...



Inferring black hole charge from backscattered electromagnetic radiation 

submitted by kosoore 19 minutes ago  Topic: Geography 

We compute the scattering cross section of ReissnerNordstr"om black holesfor the case of an incident electromagnetic wave. We describe how scattering isaffected by both the conversion of electromagnetic to gravitational radiation,and the paritydependence of phase shifts induced by the black hole charge. Thelatter effect creates a helicityreversed scattering amplitude that is nonzeroin the b...



CMB Anisotropies from a Gradient Mode 

submitted by kosoore 19 minutes ago  Topic: Geography 

A pure gradient mode must have no observable dynamical effect at linearlevel. We confirm this by showing that its contribution to the dipolar powerasymmetry of CMB anisotropies vanishes, if Maldacena's consistency condition issatisfied. To this end, the existing second order SachsWolfe formula in thesqueezed limit is extended to include a gradient in the long mode and toaccount for the change ...



