Searcharxiv⌕ Search

arXiv · 0707.1524

Finsler-Lagrange Geometries and Standard Theories in Physics: New Methods in Einstein and String Gravity

Abstract

In this article, we review the current status of Finsler-Lagrange geometry and generalizations. The goal is to aid non-experts on Finsler spaces, but physicists and geometers skilled in general relativity and particle theories, to understand the crucial importance of such geometric methods for applications in modern physics. We also would like to orient mathematicians working in generalized Finsler and Kahler geometry and geometric mechanics how they could perform their results in order to be accepted by the community ''orthodox'' physicists. Although the bulk of former models of Finsler-Lagrange spaces where elaborated on tangent bundles, the surprising result advocated in our works is that such locally anisotropic structures can be modelled equivalently on Riemann-Cartan spaces, even as exact solutions in Einstein and/or string gravity, if nonholonomic distributions and moving frames of references are introduced into consideration. We also propose a canonical scheme when geometrical objects on a (pseudo) Riemannian space are nonholonomically deformed into generalized Lagrange, or Finsler, configurations on the same manifold or on a corresponding tangent bundle. Such canonical transforms are defined by the coefficients of a prime metric (it can be a solution of the Einstein equations) and generate target spaces as generalized Lagrange structures, their models of almost Hermitian/ Kahler, or nonholonomic Riemann spaces with constant curvature, for some Finsler like connections. There are formulated the criteria when such constructions can be redefined equivalently in terms of the Levi Civita connection.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Sergiu I. Vacaru. 2008-01-31. Finsler-Lagrange Geometries and Standard Theories in Physics: New Methods in Einstein and String Gravity. https://arxiv.org/abs/0707.1524

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

Physical properties of compact star-like systems harboring traversable wormholes: Effects of chaotic magnetic fields and anisotropic matter

We formulate exotic compact objects in form of compact star-like systems harboring traversable wormhole (CSSTW) with chaotic magnetic field and pressure anisotropy of the neutron fluid. The wormhole is traversable regardless of whether anisotropy of the neutron fluid and/or magnetic fields are included. For magnetized configurations, the resulting CSSTW can become extremely massive, with ADM masses exceeding $8\,M_\odot$, and can exhibit large surface redshifts exceeding $\mathcal{Z} \simeq 1.5$. The system can also reach the ultracompact regime, which allows us to calculate echo time that might be produced by the systems. Echo times of considered CSSTW vary depending on the chaotic magnetic field configuration and fluid anisotropy. For non-magnetized configurations, the gravitational-wave echo time is of the order of $10^{-2}-10^{-1}$ ms. For the magnetized configurations, however, it ranges from the order of $10^{-1}$ $μ$s $-10^{-1}$ ms Moreover, we derive an explicit expression for the echo time as a function of uniform magnetic field. The resulting relation shows that the echo time decreases as the magnetic field strength increases. The stability analysis of radial perturbations shows that the ultracompact non-magneized CSSTW are prone to be unstable. For magnetized CSSTW, all considered configurations with a surface magnetic field of $B_s=10^{15}$ G are stable.

gr-qc↗

Strong Lensing and Quasinormal modes of a Black Hole with a Global Monopole

In this paper, we investigate various key aspects of a static and spherically symmetric black hole with a global monopole. Firstly, we analyze the deflection angle in the strong field limit of a spacetime with a global monopole. It shows that the angle of deflection increases when the two characteristic parameters for the monopole configuration, $η$ and $λ$, increase. The influence of the global monopole parameter on the lensing observables and the black hole shadow is studied. This shows that a larger monopole parameter corresponds to larger shadow radii. The dynamics of timelike geodesics is also investigated in the spacetime. General circular orbits and the innermost stable circular orbits (ISCO) of timelike particles are discussed, highlighting that the monopole parameter significantly affects the circular orbits and the ISCO. In particular, it is observed that the radius of ISCO rises monotonically with $η$. In addition, the Lyapunov exponent is used to analyze the stability of timelike geodesics. We also determine the quasinormal modes under electromagnetic perturbations for different values of $η$. Our findings indicate that increasing the monopole parameter gives rise to electromagnetic perturbations with more slowly damped oscillations. To further validate the derived quasinormal mode spectrum, we discuss the time-domain evolution of the perturbation, confirming the presence of the characteristic quasinormal ringing followed by late-time power-law tails. Finally, comparison with the EHT observations of M87* and Sgr A* determines the parameter combinations of $η$ and $λ$ compatible with current observations, and the observational prospects of the strong-lensing observables are discussed.

gr-qc↗

Modified Teukolsky Formalism for Extreme Mass-Ratio Inspirals in Higher-Derivative Gravity

In this work, we study a model problem involving a point particle spiraling into a non-rotating black hole in higher-derivative theories of gravity. In such theories, both the background spacetime and the generation and propagation of gravitational waves differ from those in General Relativity. We develop a modified Teukolsky formalism to describe gravitational waves sourced by the point particle and, as an illustrative example, compute the resulting fluxes to the black hole horizon and null infinity for a cubic gravity theory. The formalism is constructed in a way that can be naturally extended to rotating black holes. These results represent essential steps to build extreme mass-ratio-inspiral waveforms in modified gravity theories, which may also be rescaled to approximate waveforms from comparable-mass binary black hole systems, analogous to existing approaches in General Relativity.

gr-qc↗