61 citations · 382 across the 24 of their papers we have counts for
24 papers
Exact vacuum solution with Hopf structure in general relativity
Junpei Harada
An exact solution to the vacuum Einstein equations is presented, whose structure is based on the Hopf fibration. The solution employs a geodesic null vector field that defines a tw…
Gauge-invariant formulation for the gravitational wave equations
Junpei Harada
A gauge-invariant formulation for the gravitational wave equations is presented. Using this approach, weak, plane wave solutions in a vacuum are derived in various theories. These…
Gravity at cosmological distances: Explaining the accelerating expansion without dark energy
Junpei Harada
Three theoretical criteria for gravitational theories beyond general relativity are considered: obtaining the cosmological constant as an integration constant, deriving the energy…
Dark energy in conformal Killing gravity
Junpei Harada
The Friedmann equation, augmented with an additional term that effectively takes on the role of dark energy, is demonstrated to be an exact solution to the recently proposed gravit…
Cotton gravity and 84 galaxy rotation curves
Junpei Harada
Recently, as a generalization of general relativity, a gravity theory has been proposed in which gravitational field equations are described by the Cotton tensor. That theory allow…
Emergence of the Cotton tensor for describing gravity
Junpei Harada
It is shown that the Cotton tensor can describe the effects of gravity beyond general relativity. Any solution of the Einstein equations with or without the cosmological constant s…