Demagnified GWs from Cosmological Double Neutron Stars and GW Foreground Cleaning Around 1Hz (2009)
Gravitational waves from cosmological double neutron star binaries can be significantly demagnified by strong gravitational lensing effect, and the proposed future missions such as BBO or DECIGO...
The merger of a super-massive binary black hole (SBBH) is one of the most extreme events in the universe with a huge amount of energy released by gravitational radiation. Although the characteristic...
Non-Gaussianity analysis of GW background made by short-duration burst signals (2009)
We study an observational method to analyze non-Gaussianity of a gravitational wave (GW) background made by superposition of weak burst signals. The proposed method is based on fourth-order...
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...
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...
Non-Gaussianity test for discriminating gravitational wave backgrounds around 0.1-1Hz (2008)
We propose a non-Gaussianity test for gravitational wave backgrounds by combining data streams of multiple detectors. This simple method allows us to check whether a detected background is "smooth"...
Detecting Planets around Compact Binaries with Gravitational Wave Detectors in Space (2008)
I propose a method to detect planets around compact binaries that are strong sources of gravitational radiation. This approach is to measure gravitational-wave phase modulations induced by the...
The Stokes V parameter characterizes asymmetry of amplitudes between right- and left-handed waves, and non-vanishing value of the V parameter yields a circularly polarized signal. Cosmologically, V...
Nonlinear Evolution Of The Genus Statistics With Zel'dovich Approximation (2007)
Naoki Seto, Takahiko Matsubara, Masaru Siino
Evolution of genus density is calculated from Gaussian initial conditions using Zel'dovich approximation. A new approach is introduced which formulates the desired quantity in a rotationally...
We show that pairs of widely separated interferometers are advantageous for measuring the Stokes parameter V of a stochastic background of gravitational waves. This parameter characterizes asymmetry...
Searching for primordial black hole dark matter with pulsar timing arrays (2007)
We discuss the possibility of detecting the presence of primordial black holes (PBHs), such as those that might account for galactic dark matter, using modification of pulsar timing residuals when...
We show that isotropic component of circular polarization of stochastic gravitational wave background can be explored by breaking two dimensional configuration of multiple laser interferometers for...
Prospects for direct detection of circular polarization of gravitational-wave background (2006)
We discussed prospects for directly detecting circular polarization signal of gravitational wave background. We found it is generally difficult to probe the monopole mode of the signal due to broad...
Correlation analysis of stochastic gravitational wave background around 0.1–1 Hz (2006)
We discuss prospects for direct measurement of stochastic gravitational wave background around 0.1–1 Hz with future space missions. It is assumed to use correlation analysis technique with the...
Cosmological constraints on the very low frequency gravitational-wave background (2006)
The curl modes of cosmic microwave background polarization allow one to indirectly constrain the primordial background of gravitational waves with frequencies around 10^(-18) to 10^(-16) Hz. The...
We study prospects of a method to constrain the inclination of a coalescing compact binary by detecting its gravitational waves associated with a three-dimensionally localized (direction and...
Correlation analysis of stochastic gravitational wave background around 0.1-1Hz (2005)
We discuss prospects for direct measurement of stochastic gravitational wave background around 0.1-1Hz with future space missions. It is assumed to use correlation analysis technique with the optimal...
Did WMAP see Moving Local Structures? (2005)
The divergence of the momentum density field of the large scale structure generates a secondary anisotropy contribution to the Cosmic Microwave Background (CMB). While the effect is best described as...
Probing the Largest Scale Structure in the Universe with Polarization Map of Galaxy Clusters (2005)
We introduce a new formalism to describe the polarization signal of galaxy clusters on the whole sky. We show that a sparsely sampled, half-sky map of the cluster polarization at z~1 would allow us...
We discuss an astrometric timing effect on data analysis of continuous gravitational waves from rapidly rotating isolated neutron stars. Special attention is directed to the possibility of...
Probing the largest scale structure in the universe with polarization map of galaxy clusters (2005)
We introduce a new formalism to describe the polarization signal of galaxy clusters on the whole sky. We show that a sparsely sampled, half-sky map of the cluster polarization signal at $z\sim 1$...
Can LISA Resolve Distance to the Large Magellanic Cloud? (2005)
The Laser Interferometer Space Antenna (LISA) is expected to detect N ~ 22 [x10^(+/- 1)] close white dwarf binaries in the Large Magellanic Cloud (LMC) through their gravitational radiation with...
Cosmological Constraints on the Very Low Frequency Gravitational-Wave Background (2005)
While there are no strong observational constraints on the gravitational wave background across six or more orders of magnitude between 10^{-16} Hz and 10^{-10} Hz and it is difficult to get a...
We discuss spatial fluctuations in the gravitational wave background arising from unresolved Galactic binary sources, such as close white dwarf binaries, due to the fact the galactic binary source...
Search for small-mass black-hole dark matter with space-based gravitational wave detectors (2004)
If the halo dark matter were composed of primordial black holes (PBHs) with mass between 10^16 and 10^20 g, their gravitational interaction with test masses of laser interferometer may lead to a...
Graviton mass from close white dwarf binaries detectable with LISA (2004)
The arrival times of gravitational waves and optical light from orbiting binaries provide a mechanism to understand the propagation speed of gravity when compared to that of light or electromagnetic...
Search for Small-Mass Black Hole Dark Matter with Space-Based Gravitational Wave Detectors (2004)
The high sensitivity of upcoming space-based gravitational wave detectors suggests the possibility that if halo dark matter were composed of primordial black holes (PBHs) with mass between $10^{16}$...
We discuss spatial fluctuations in the gravitational wave background arising from unresolved Galactic binary sources, such as close white dwarf binaries, due to the fact the galactic binary source...
Annual modulation of the Galactic binary confusion noise bakground and LISA data analysis (2004)
We study the anisotropies of the Galactic confusion noise background and its effects on LISA data analysis. LISA has two data streams of the gravitational waves signals relevant for low frequency...
Graviton Mass from Close White Dwarf Binaries Detectable with LISA (2003)
The arrival times of gravitational waves and optical light from orbiting binaries provide a mechanism to understand the propagation speed of gravity when compared to that of light or electromagnetic...
Optical Identification of Close White Dwarf Binaries in the LISA Era (2003)
Cooray, Asantha, Farmer, Alison J., Seto, Naoki
The Laser Interferometer Space Antenna (LISA) is expected to detect close white dwarf binaries (CWDBs) through their gravitational radiation. Around 3000 binaries will be spectrally resolved at...
We study how the angular resolution of LISA for merging massive black-hole binaries would be improved if we observe multiple gravitational wave ``images'' due to strong gravitational lensing. The...
Probing the equation of state of the early universe with a space laser interferometer (2003)
Seto, Naoki, Yokoyama, Jun'Ichi
We propose a method to probe the equation of state of the early universe and its evolution, using the stochastic gravitational wave background from inflation. A small deviation from purely radiation...
Effects of finite arm-length of LISA on analysis of gravitational waves from MBH binaries (2002)
Response of an interferometer becomes complicated for gravitational wave shorter than the arm-length of the detector, as nature of wave appears strongly. We have studied how parameter estimation for...
Parameter estimation for Galactic binaries by LISA (2002)
Takahashi, Ryuichi, Seto, Naoki
We calculate how accurately parameters of the short-period binaries $(10^{-4} {Hz} \lsim f\lsim 10^{-2} {Hz})$ will be determined from the gravitational waves by LISA. In our analysis the chirp...
Long Term Operation of LISA and Galactic Close White Dwarf Binaries (2002)
The binary confusion noise spectrum at LISA band depends strongly on observational period and abundance of Galactic close white dwarf binaries (CWDBs). We have investigated how the number of the...
We propose a new method for determining total masses of low frequency eccentric binaries (such as, neutron star binaries with orbital frequency $f\gsim 10^{-3}$Hz) from their gravitational waves. In...
Seto, Naoki, Kawamura, Seiji, Nakamura, Takashi
It may be possible to construct a laser interferometer gravitational wave antenna in space with $h_{rms}\sim 10^{-27}$ at $ f\sim 0.1{\rm Hz}$ in this century. We show possible specification of this...
Numerical Analyses of Weakly Nonlinear Velocity-Density Coupling (2001)
We study evolution of various statistical quantities of smoothed cosmic density and velocity fields using N-body simulations. The parameter $C\equiv /( )$ characterizes nonlinear coupling of these...
Evolution of Power Spectrum in Non-Gaussian Models (2001)
Evolution of power spectrum is studied for non-Gaussian models of structure formation. We generalize the dark-matter-approach to these models and find that the evolved spectrum at weakly nonlinear...
We examine the polarization signal of the cosmic microwave background radiation associated with distant clusters. The polarization is induced by the Thomson scattering of microwave photons with...
Nonlinear Velocity-Density Coupling: Analysis by Second-Order Perturbation Theory (2000)
Cosmological linear perturbation theory predicts that the peculiar velocity $V(x)$ and the matter overdensity $\delta(x)$ at a same point $x$ are statistically independent quantities, as log as the...
Perturbative Analysis of Adaptive Smoothing Methods in Quantifying Large-Scale Structure (2000)
Smoothing operation to make continuous density field from observed point-like distribution of galaxies is crucially important for topological or morphological analysis of the large-scale structure,...
Sample Variance of the Higher-Order Cumulants of Cosmic Density and Velocity Fields (1998)
Seto, Naoki, Yokoyama, Jun'ichi
If primordial fluctuation is Gaussian distributed, higher-order cumulants of the cosmic fields reflect nonlinear mode coupling and provide useful information of gravitational instability picture of...
Sample variance of the cosmic velocity field (1998)
Seto, Naoki, Yokoyama, Jun'ichi
Since the cosmic peculiar velocity field depends on small wave-number modes strongly, we cannot probe its universal properties unless we observe a sufficiently large region. We calculate the expected...
Seto, Naoki, Yokoyama, Jun'ichi
The statistical distribution of the radial pairwise peculiar velocity of galaxies is known to have an exponential form as implied by observations and explicitly shown in N-body simulations. Here we...
Nonlinear Evolution of the Genus Statistics with Zel'dovich Approximation (1996)
Seto, Naoki, Yokoyama, Jun'ichi, Matsubara, Takahiko, Siino, Masaru
Evolution of genus density is calculated from Gaussian initial conditions using Zel'dovich approximation. A new approach is introduced which formulates the desired quantity in a rotationally...