We calculate energy and momentum of a spherically symmetric dilaton frame using the gravitational energy-momentum 3-form within the tetrad formulation of general relativity (GR). The frame we use is characterized by an arbitrary function $Υ$ with the help of which all the previously found solutions can be reproduced. We show how the effect of inertia {\it (which is mainly reproduced from $Υ$)} makes the total energy and momentum always different from the well known result when we use the Riemannian connection ${{\widetilde Γ}_α}^β$. On the other hand, when use is made of the covariant formulation of teleparallel gravity, which implies to take into account the pure gauge connection, teleparallel gravity always yields the physically relevant result for the energy and momentum.
A note on classification of proper teleparallel conformal symmetries of spherically symmetric static space-times in the teleparallel theory of gravitation using diagonal tetrads
In \cite{Bahamonde:2019zea}, a spherically symmetric black hole (BH) was derived from the quadratic form of $f(T)$. Here we derive the associated energy, invariants of curvature, and torsion of this BH and demonstrate that the higher-order contribution of torsion renders the singularity weaker compared with the Schwarzschild BH of general relativity (GR). Moreover, we calculate the thermodynamic quantities and reveal the effect of the higher--order contribution on these quantities. Therefore, we derive a new spherically symmetric BH from the cubic form of $f(T)=T+ε\Big[\frac{1}{2}αT^2+\frac{1}…
An important characteristic of the Dilaton cosmological model is the Gasperini-Veneziano duality transformation which follows from the existence of the $O\left( d,d\right) $ symmetry. In this study, we consider the equivalent Dilaton theory in teleparallel dark energy with the $O\left( d,d\right) $ symmetry, while the equivalent teleparallel-duality transformation is presented. The classical solution of the field equations is derived. Finally the Wheeler-DeWitt equation of quantum cosmology is discussed.
A static spherically symmetric solution is obtained and examined in the framework of Einstein-power-Yang-Mills-dilaton theory. To derive this exact solution a dilaton potential $V(Φ)$ is taken into account. Thermodynamics of the black hole is also studied, namely we have obtained and investigated the temperature and heat capacity of the black hole which has allowed us characterize the stability of the black hole. Using the framework of the extended thermodynamic phase space we have derived the equation of state for the black hole. We have studied the Gibbs free energy of the black hole, which …
A static black hole with spherical symmetry is obtained and examined in the framework of Einstein-Yang-Mills-dilaton theory. The obtained black hole solution allowed us to derive and investigate entropy, temperature and heat capacity. To better examine the thermodynamics of the black hole extended phase space is also used. On this ground the equation of state is obtained and studied. We have also investigated the Gibbs free energy and it is shown that below the critical temperature the system demonstrates phase transitions of the first as well as of the zeroth order which is notable feature fo…
In this work a static spherically symmetric black hole's solution within the Einstein-Maxwell-Yang-Mills-dilaton theory is derived. The obtained solution is examined, in particular, we have calculated the Kretschmann scalar which allowed us to characterize singularity points. Using the obtained black hole's solution we have studied its thermodynamics. Namely, the temperature was calculated, the first law was written, and the heat capacity was studied. The extended thermodynamics approach is utilized to obtain the equation of state. Within the extended thermodynamics the Gibbs free energy is de…
With the advent of gravitational wave astronomy and first pictures of the "shadow" of the central black hole of our milky way, theoretical analyses of black holes (and compact objects mimicking them sufficiently closely) have become more important than ever. The near future promises more and more detailed information about the observable black holes and black hole candidates. This information could lead to important advances on constraints on or evidence for modifications of general relativity. More precisely, we are studying the influence of weak teleparallel perturbations on general relativi…
In symmetric teleparallel gravities, where the independent connection is characterized by nonmetricity while curvature and torsion are zero, it is possible to find a coordinate system whereby the connection vanishes globally and covariant derivatives reduce to partial derivatives -- the coincident gauge. In this paper we derive general transformation rules into the coincident gauge for spacetime configurations where the both the metric and connection are static and spherically symmetric, and write out the respective form of the coincident gauge metrics. Taking different options in fixing the f…
Symmetric teleparallel gravity is constructed with a nonzero nonmetricity tensor while both torsion and curvature are vanishing. In this framework, we find exact scalarised spherically symmetric static solutions in scalar-tensor theories built with a nonminimal coupling between the nonmetricity scalar and a scalar field. It turns out that the Bocharova-Bronnikov-Melnikov-Bekenstein solution has a symmetric teleparallel analogue (in addition to the recently found metric teleparallel analogue), while some other of these solutions describe scalarised black hole configurations that are not known i…
f(Q) gravity is the extension of symmetric teleparallel general relativity (STGR), in which both curvature and torsion vanish, and gravity is attributed to nonmetricity. This work performs theoretical analyses of static and spherically symmetric solutions with an anisotropic fluid for general f(Q) gravity. We find that the off-diagonal component of the field equation due to a coincident gauge leads to stringent restrictions on the functional form of f(Q) gravity. In addition, although the exact Schwarzschild solution only exists in STGR, we obtain Schwarzschild-like solutions in nontrivial f(Q…
Phase-plane analysis of the timelike geodesics around a spherically symmetric static dilaton black hole
本文用动力系统方法研究了在Einstein坐标系下，自由测试粒子围绕球对称静态黑洞黑洞运动的方程。运动方程采用欧拉-拉格朗日形式。利用第一次运动积分，我们得出了自由测试粒子在一个平面内运动的结论，命名为\emph{plane of motion}。在其中，我们分析了平衡点的存在性和性质，并使用动力学系统方法比较了平衡点附近自由测试粒子的行为。研究表明，在精确的相平面中存在不同的运动区域，通过一条名为\emph{separatrix}的曲线分开。最后得到了描述黑洞的参数与处于抛物分界线上的自由测试粒子之间的关系。
The uniqueness theorem for static, spherically symmetric, asymptotically flat, higher dimensional phantom black holes, with non-degenerate event horizon , being the solutions of Einstein phantom/dilaton Maxwell/anti-Maxwell gravity systems is considered. Conformal positive energy theorem and conformal transformations authorize the crucial tools for exploiting the boundary conditions and conformal flatness.
