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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 2-form 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 quasi-local 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 thegauge-invariant 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...

Spacetime is Locally Inertial at Points of General Relativistic Shock Wave Interaction between Shocks from Different Characteristic Families
submitted by kosoore 19 minutes ago - Topic: Geography
We prove that spacetime is locally inertial at points of shock wave collisionin General Relativity. The result applies for collisions between shock wavescoming from different characteristic families, in spherically symmetricspacetimes. We give a constructive proof that there exist coordinatetransformations which raise the regularity of the gravitational metric tensorfrom $C^{0,1}$ to $C^{1,1}$ ...

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 non-classical 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 type-I spacetime: Problems and Possibilities
submitted by kosoore 19 minutes ago - Topic: Geography
Within the scope of Bianchi type-I 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 becomesnon-diagonal, whereas the Einstein tensor is diagonal. This non-triviality ofnon-diagonal components of the energy-momentum tensor imposes some severerestrictions either on th...


Cauchy problem as a two-surface based `geometrodynamics'
submitted by kosoore 19 minutes ago - Topic: Geography
Four-dimensional spacetimes foliated by a two-parameter family of homologoustwo-surfaces 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 two-surfacesa 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...


New Solutions of the 2+1 Dimensional Einstein Gravity Coupled to Maxwell Power type Non Linear Electric field with Dilaton field
submitted by kosoore 19 minutes ago - Topic: Geography
New solutions are derived in the 2+1 gravity which is coupled to ${calF}^k$ type non-linear electric field in Maxwell Power theory with dilatonfield. We obtain consistent solutions in general $k$ case. We also investigatethe behavior of the metric function with the space-time singularity. Then, wefound some black hole solutions when the space-time has a singular point at$r=0$. Addition, we deri...

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 non-vanishing 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 domain-wall 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 Reissner-Nordstr"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 parity-dependence of phase shifts induced by the black hole charge. Thelatter effect creates a helicity-reversed scattering amplitude that is non-zeroin 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 Sachs-Wolfe formula in thesqueezed limit is extended to include a gradient in the long mode and toaccount for the change ...

Resolving the relative influence of strong field spacetime dynamics and MHD on circumbinary disk physics
submitted by kosoore 19 minutes ago - Topic: Geography
In this paper we evolve magnetized and unmagnetized circumbinary accretiondisks around supermassive black hole binaries in the relativistic regime. Weuse a post-Newtonian expansion to construct an analytical spacetime anddetermine how the order of the post-Newtonian (PN) expansion affects thedynamics of the gas. We find very small differences in the late-time bulkdynamics of non-magnetized hydr...