Abstract In this paper, we investigate the photon sphere, shadow radius and quasinormal modes of a four-dimensional charged Einstein–Gauss–Bonnet black hole. The perturbation massless scalar field in hole’s background is adopted. are gotten by 6th order WKB approximation approach radius, respectively. When value Gauss–Bonnet coupling constant increase, values real parts increase those imaginary...

By employing the general expression of temperature Th = |κ|/2π = 1 2πr̃A (1 − ̇̃ rA 2Hr̃A ) associated with the apparent horizon of a FRW universe and assuming a region of FRW universe enclosed by the apparent horizon as a thermal system in equilibrium, we are able to show that the generalized second law of thermodynamics holds in Gauss-Bonnet gravity and in more general Lovelock gravity. PACS num...

We propose a novel but natural definition of conserved quantities for gravity models quadratic and higher in curvature. Based on the spatial asymptotics of curvature rather than of metric, it avoids the GR energy machinery’s more egregious problems–such as zero energy “theorems” and failure in flat backgrounds – in this fourth-derivative realm. In D > 4, the present expression indeed correctly ...

We present a grapical way to describe invariants and covariants in the (4 dim) general relativity. This makes us free from the complexity of suffixes . Two new off-shell relations between (mass)∗∗6 invariants are obtained. These are important for 2-loop off-shell calculation in the perturbative quantum gravity. We list up all independent invarians with dimensions of (mass)∗ ∗ 4 and (mass)∗∗6. F...

A generalized teleparallel cosmological model, [Formula: see text], containing the torsion scalar T and the teleparallel counterpart of the Gauss-Bonnet topological invariant [Formula: see text], is studied in the framework of the Noether symmetry approach. As [Formula: see text] gravity, where [Formula: see text] is the Gauss-Bonnet topological invariant and R is the Ricci curvature scalar, ex...

Lovelock gravity is an important extension of General Relativity that provides a promising framework to study curvature corrections to the Ein-stein action, while avoiding ghosts and keeping second order field equations. This paper derives the greybody factors for D-dimensional black holes arising in a theory with a Gauss-Bonnet curvature-squared term. These factors describe the non-trivial cou...

We construct a solitonic 3-brane solution in the 6-dimensional EinsteinHilbert-Gauss-Bonnet theory with a (negative) cosmological term. This solitonic brane world is δ-function-like. Near the brane the metric is that for a product of the 4-dimensional flat Minkowski space with a 2-dimensional “wedge” with a deficit angle (which depends on the solitonic brane tension). Far from the brane the met...

Dark energy cosmologies with an equation of state parameter w less than −1 are often found to violate the null energy condition and show unstable behaviour. A solution to this problem may require the existence of a consistent effective theory that violates the null energy condition only momentarily and does not develop any instabilities or other pathological features for a late time cosmology. ...

The d-dimensional string generated gravity models lead to Einstein-Maxwell equations with quadratic order correction term called the Gauss-Bonnet term. We calculate the quasinormal modes for the d-dimensional charged black hole in the framework of this model. The quasinormal spectrum essentially depends upon the Gauss-Bonnet coupling parameter α which is related to the string scale, and is tota...