Static spherically symmetric solutions in the IR limit of nonrelativistic quantum gravity (2009)
Harada, Tomohiro, Miyamoto, Umpei, Tsukamoto, Naoki
We investigate static spherically symmetric vacuum solutions in the IR limit of projectable nonrelativistic quantum gravity, including the renormalisable quantum gravity recently proposed by...
Stability of branes trapped by d-dimensional black holes (2009)
Hioki, Kenta, Miyamoto, Umpei, Nozawa, Masato
The system of extended objects interplaying with a black hole describes or mimics various gravitational phenomena. In this brief paper, we report the results of stability analysis of codimension-one...
The Bernstein Conjecture, Minimal Cones, and Critical Dimensions (2009)
Gibbons, Gary W., Maeda, Kei-ichi, Miyamoto, Umpei
Minimal surfaces and domain walls play important roles in various contexts of spacetime physics as well as material science. In this paper, we first review the Bernstein conjecture, which asserts...
Black hole-black string phase transitions from hydrodynamics (2008)
Maeda, Kei-ichi, Miyamoto, Umpei
We discuss the phase transitions between three states of a plasma fluid (plasma ball, uniform plasma tube, and non-uniform plasma tube), which are dual to the corresponding finite energy black...
Hidden symmetries, null geodesics, and photon capture in the Sen black hole (2008)
Important classes of null geodesics and hidden symmetries in the Sen black hole are investigated. First, we obtain the principal null geodesics and circular photon orbits. Then, an irreducible...
Curvature driven diffusion, Rayleigh-Plateau, and Gregory-Laflamme (2008)
It can be expected that the respective endpoints of the Gregory-Laflamme black brane instability and the Rayleigh-Plateau membrane instability are related because the bifurcation diagrams of the...
Liquid bridges and black strings in higher dimensions (2008)
Miyamoto, Umpei, Maeda, Kei-ichi
Analyzing a capillary minimizing problem for a higher-dimensional extended fluid, we find that there exist startling similarities between the black hole-black string system (the Gregory-Laflamme...
Generic features of Einstein-Aether black holes (2007)
Tamaki, Takashi, Miyamoto, Umpei
We reconsider spherically symmetric black hole solutions in Einstein-Aether theory with the condition that this theory has identical PPN parameters as those for general relativity, which is the main...
Analytic evidence for the Gubser-Mitra conjecture (2007)
A simple master equation for the static perturbation of charged black strings is derived while employing the gauge proposed by Kol. As the charge is varied it is found that the potential in the...
Hawking radiation of a vector field and gravitational anomalies (2007)
Murata, Keiju, Miyamoto, Umpei
Recently, the relation between Hawking radiation and gravitational anomalies has been used to estimate the flux of Hawking radiation for a large class of black objects. In this paper, we extend the...
High and Low Dimensions in The Black Hole Negative Mode (2007)
Asnin, Vadim, Gorbonos, Dan, Hadar, Shahar, Kol, Barak, Levi, Michele, Miyamoto, Umpei
The negative mode of the Schwarzschild black hole is central to Euclidean quantum gravity around hot flat space and for the Gregory-Laflamme black string instability. We analyze the eigenvalue as a...
On Hawking radiation from black rings (2007)
Miyamoto, Umpei, Murata, Keiju
We calculate the quantum radiation from the five dimensional charged rotating black rings by demanding the radiation to eliminate the possible anomalies on the horizons. It is shown that the...
New stable phase of non-uniform charged black strings (2006)
Miyamoto, Umpei, Kudoh, Hideaki
Non-uniform black strings coupled to a gauge field are constructed by a perturbative method in a wide range of spacetime dimensions. At the linear order of perturbations, we see that the...
On non-uniform smeared black branes (2005)
Kudoh, Hideaki, Miyamoto, Umpei
We investigate charged dilatonic black $p$-branes smeared on a transverse circle. The system can be reduced to neutral vacuum black branes, and we perform static perturbations for the reduced system...
Quantum Effect and Curvature Strength of Naked Singularities (2004)
Miyamoto, Umpei, Maeda, Hideki, Harada, Tomohiro
There are many solutions to the Einstein field equations that demonstrate naked singularity (NS) formation after regular evolution. It is possible, however, that such a quantum effect as particle...
Semiclassical Instability of the Cauchy Horizon in Self-Similar Collapse (2003)
Miyamoto, Umpei, Harada, Tomohiro
Generic spherically symmetric self-similar collapse results in strong naked-singularity formation. In this paper we are concerned with particle creation during a naked-singularity formation in...
Particle velocity in noncommutative space-time (2002)
Tamaki, Takashi, Harada, Tomohiro, Miyamoto, Umpei, Torii, Takashi
We investigate a particle velocity in the $\kappa$-Minkowski space-time, which is one of the realization of a noncommutative space-time. We emphasize that arrival time analyses by high-energy...
Have we already detected astrophysical symptoms of space-time noncommutativity ? (2001)
Tamaki, Takashi, Harada, Tomohiro, Miyamoto, Umpei, Torii, Takashi
We discuss astrophysical implications of $\kappa$-Minkowski space-time, in which there appears space-time noncommutativity. We first derive a velocity formula for particles based on the motion of a...