33 citations · 138 across the 13 of their papers we have counts for
13 papers
Wave propagation and shock formation in the most general scalar-tensor theories
Norihiro Tanahashi, Seiju Ohashi
This work studies wave propagation in the most general scalar-tensor theories, particularly focusing on the causal structure realized in these theories and also the shock formation…
Violation of cosmic censorship in the gravitational collapse of a dust cloud in five dimension
Ryosuke Mizuno, Seiju Ohashi, Tetsuya Shiromizu
We analyze the null geodesic equations in five dimensional spherically symmetric spacetime with collapsing inhomogeneous dust cloud. By using a new method, we prove the existence a…
Lovelock black holes with non-constant curvature horizon
Seiju Ohashi, Masato Nozawa
This paper studies a class of dimensional solutions to Lovelock gravity that is described by the warped product of a two-dimensional Lorentzian metric and an -dim…
The most general second-order field equations of bi-scalar-tensor theory in four dimensions
Seiju Ohashi, Norihiro Tanahashi, Tsutomu Kobayashi +1
The Horndeski theory is known as the most general scalar-tensor theory with second-order field equations. In this paper, we explore the bi-scalar extension of the Horndeski theory.…
Strictly static spacetimes and positive mass in the Einstein-Gauss-Bonnet theory
Tetsuya Shiromizu, Seiju Ohashi
In the Einstein gravity, it is well-known that strictly stationary and vacuum regular spacetime should be the Minkowski spacetime. In the Einstein-Gauss-Bonnet theory, we shall sho…
A no-go on strictly stationary spacetimes in four/higher dimensions
Tetsuya Shiromizu, Seiju Ohashi, Ryotaku Suzuki
We show that strictly stationary spacetimes cannot have non-trivial configurations of form fields/complex scalar fields and then the spacetime should be exactly Minkowski or anti-d…
Gravitational collapse of charged dust cloud in the Lovelock gravity
Seiju Ohashi, Tetsuya Shiromizu, Sanjay Jhingan
We study the effect of charge on gravitational collapse of inhomogeneous dust cloud in the Einstein, Gauss-Bonnet and Lovelock gravity. Dynamics of the collapsing shell is analyzed…
Spherical collapse of inhomogeneous dust cloud in the Lovelock theory
Seiju Ohashi, Tetsuya Shiromizu, Sanjay Jhingan
We study gravitational collapse of a spherically symmetric inhomogeneous dust cloud in the Lovelock theory without cosmological constant. We show that the final fate of gravitation…
A perturbative no-hair of form fields for higher dimensional static black holes
Tetsuya Shiromizu, Seiju Ohashi, Kentaro Tanabe
In this paper we examine the static perturbation of p-form field strengths around higher dimensional Schwarzschild spacetimes. As a result, we can see that the static perturbations…
Multipole moments for black objects in five dimensions
Kentaro Tanabe, Seiju Ohashi, Tetsuya Shiromizu
In higher dimensions than four, conventional uniqueness theorem in asymptotically flat space-times does not hold, i.e., black objects can not be classified only by the mass, angula…
No-dipole-hair theorem for higher-dimensional static black holes
Roberto Emparan, Seiju Ohashi, Tetsuya Shiromizu
We prove that static black holes in n-dimensional asymptotically flat spacetime cannot support non-trivial electric p-form field strengths when (n+1)/2<= p <= n-1. This implies in…
Static black hole uniqueness and Penrose inequality
Ryosuke Mizuno, Seiju Ohashi, Tetsuya Shiromizu
Under certain conditions, we give a new way to prove the uniqueness of static black hole in higher dimensional asymptotically flat spacetimes. In the proof, the Penrose inequality…
The Riemannian Penrose inequality and a virtual gravitational collapse
Seiju Ohashi, Tetsuya Shiromizu, Sumio Yamada
We reinterpret the proof of the Riemannian Penrose inequality by H. Bray. The modified argument turns out to have a nice feature so that the flow of Riemannian metrics appearing Br…