Probing Tensor-Vector-Scalar Theory with Gravitational Wave Asteroseismology (2009)
In order to examine the gravitational waves emitted from the neutron stars in the tensor-vector-scalar (TeVeS) theory, we derive the perturbation equations for relativistic stars, where for...
Ando, Masaki, Kawamura, Seiji, Sato, Shuichi, Nakamura, Takashi, Tsubono, Kimio, Araya, Akito, ...
DECIGO pathfinder (DPF) is a milestone satellite mission for DECIGO (DECi-hertz Interferometer Gravitational wave Observatory), which is a future space gravitational wave antenna. DECIGO is expected...
Gravitational Radiation from Collapsing Magnetized Dust. II -- Polar Parity Perturbation -- (2009)
With the gauge-invariant perturbation theory, we study the effects of the stellar magnetic fields on the polar gravitational waves emitted during the homogeneous dust collapse. We found that the...
Stellar Oscillations in Tensor-Vector-Scalar Theory (2009)
An alternative theory of gravity has recently been proposed by Bekenstein, named Tensor-Vector-Scalar (TeVeS) theory, which can explain many galactic and cosmological observations without the need...
Structure of Neutron Stars in Tensor-Vector-Scalar Theory (2008)
Lasky, Paul D., Sotani, Hajime, Giannios, Dimitrios
Bekenstein's Tensor-Vector-Scalar (TeVeS) theory has had considerable success in explaining various phenomena without the need for dark matter. However, it is difficult to observationally discern the...
Ando, Masaki, Kawamura, Seiji, Nakamura, Takashi, Tsubono, Kimio, Tanaka, Takahiro, Funaki, Ikkoh, ...
DECIGO pathfinder (DPF) is a milestone satellite mission for DECIGO (DECi-hertz Interferometer Gravitational wave Observatory) which is a future space gravitational wave antenna. DECIGO is expected...
The Japanese space gravitational wave antenna; DECIGO (2008)
Kawamura, Seiji, Ando, Masaki, Nakamura, Takashi, Tsubono, Kimio, Tanaka, Takahiro, Funaki, Ikkoh, ...
DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) is the future Japanese space gravitational wave antenna. DECIGO is expected to open a new window of observation for gravitational...
Structure of neutron stars in tensor-vector-scalar theory (2008)
Lasky, Paul D., Sotani, Hajime, Giannios, Dimitrios
Bekenstein's tensor-vector-scalar (TeVeS) theory has had considerable success in explaining various phenomena without the need for dark matter. However, it is difficult to observationally discern the...
Structure of neutron stars in tensor-vector-scalar theory (2008)
Lasky, Paul D., Sotani, Hajime, Giannios, Dimitrios
Bekenstein's tensor-vector-scalar (TeVeS) theory has had considerable success in explaining various phenomena without the need for dark matter. However, it is difficult to observationally discern the...
Alfv\'en QPOs in Magnetars (2007)
Sotani, Hajime, Kokkotas, Kostas, Stergioulas, Nikolaos
We investigate torsional Alfv\'en oscillations of relativistic stars with a global dipole magnetic field, via two-dimensional numerical simulations. We find that a) there exist two families of...
Gravitational radiation from collapsing magnetized dust (2007)
Sotani, Hajime, Yoshida, Shijun, Kokkotas, Kostas D.
In this article we study the influence of magnetic fields on the axial gravitational waves emitted during the collapse of a homogeneous dust sphere. We found that while the energy emitted depends...
Probing strong-field scalar-tensor gravity with gravitational wave asteroseismology (2006)
Sotani, Hajime, Kokkotas, Kostas D.
We present an alternative way of tracing the existence of a scalar field based on the analysis of the gravitational wave spectrum of a vibrating neutron star. Scalar-tensor theories in strong-field...
Stellar oscillations in scalar-tensor theory of gravity (2006)
Sotani, Hajime, Kokkotas, Kostas D.
We derive the perturbation equations for relativistic stars in scalar-tensor theories of gravity and study the corresponding oscillation spectrum. We show that the frequency of the emitted...
Gravitational waves from a dust disk around a Schwarzschild black hole (2006)
Sotani, Hajime, Saijo, Motoyuki
We investigate gravitational waves from a dust disk around a Schwarzschild black hole to focus on whether we can extract any of its physical properties from a direct detection of gravitational waves....
Sotani, Hajime, Tatekawa, Takayuki
For the evolution of density fluctuation in nonlinear cosmological dynamics, adhesion approximation (AA) is proposed as a phenomenological model, which is especially useful for describing nonlinear...
Gravitational waves from a dust disk around a Schwarzschild black hole (2005)
Sotani, Hajime, Saijo, Motoyuki
We investigate gravitational waves from a dust disk around a Schwarzschild black hole to focus on whether we can extract any of its physical properties from a direct detection of gravitational waves....
Stellar Oscillations in Scalar-Tensor Theory of Gravity (2005)
Sotani, Hajime, Kokkotas, Kostas D.
We derive the perturbation equations for relativistic stars in scalar-tensor theories of gravity and study the corresponding oscillation spectrum. We show that the frequency of the emitted...
Probing Strong-Field Scalar-Tensor Gravity with Gravitational Wave Asteroseismology (2004)
Sotani, Hajime, Kokkotas, Kostas D.
We present an alternative way of tracing the existence of a scalar field based on the analysis of the gravitational wave spectrum of a vibrating neutron star. Scalar-tensor theories in strong-field...
Restricting quark matter models by gravitational wave observation (2003)
Sotani, Hajime, Kohri, Kazunori, Harada, Tomohiro
We consider the possibilities for obtaining information about the equation of state for quark matter by using future direct observational data on gravitational waves. We study the nonradial...
Nonradial oscillations of quark stars (2003)
Sotani, Hajime, Harada, Tomohiro
Recently, it has been reported that a candidate for a quark star may have been observed. In this article, we pay attention to quark stars with radiation radii in the reported range. We calculate...
Density Discontinuity of a Neutron Star and Gravitational Waves (2001)
Sotani, Hajime, Tominaga, Kazuhiro, Maeda, Kei-ichi
We calculate quasi-normal f- and g-modes of a neutron star with density discontinuity, which may appear in a phase transition at extreme high density. We find that discontinuity will reflect largely...