Kuroyanagi, Sachiko, Tashiro, Hiroyuki, Sugiyama, Naoshi
We numerically study the interaction of inflation-produced magnetic fields with gravitational waves, both of which originate from quantum fluctuations during inflation. The resonance between the...
S-Z power spectrum produced by primordial magnetic fields (2009)
Tashiro, Hiroyuki, Sugiyama, Naoshi
Primordial magnetic fields generated in the very early universe are one of the candidates for the origin of magnetic fields observed in galaxy clusters. After recombination, the Lorentz force acts on...
Simulations of Wide-Field Weak Lensing Surveys I: Basic Statistics and Non-Gaussian Effects (2009)
Sato, Masanori, Hamana, Takashi, Takahashi, Ryuichi, Takada, Masahiro, Yoshida, Naoki, Matsubara, Takahiko, ...
We study the lensing convergence power spectrum and its covariance for a standard LCDM cosmology. We run 400 cosmological N-body simulations and use the outputs to perform a total of 1000 independent...
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...
Constraints on neutrino masses from WMAP5 and BBN in the lepton asymmetric universe (2009)
Shiraishi, Maresuke, Ichikawa, Kazuhide, Ichiki, Kiyotomo, Sugiyama, Naoshi, Yamaguchi, Masahide
In this paper, we put constraints on neutrino properties such as mass $m_{\nu}$ and degeneracy parameters $\xi_i$ from WMAP5 data and light element abundances by using a Markov chain Monte Carlo...
Observing the Evolution of the Universe (2009)
Aguirre, James, Amblard, Alexandre, Ashoorioon, Amjad, Baccigalupi, Carlo, Balbi, Amedeo, Bartlett, James, ...
How did the universe evolve? The fine angular scale (l>1000) temperature and polarization anisotropies in the CMB are a Rosetta stone for understanding the evolution of the universe. Through detailed...
The 21cm Signature of Early Relic \HII Regions (2009)
Tokutani, Midori, Yoshida, Naoki, Oh, S. Peng, Sugiyama, Naoshi
We calculate the spin temperature and 21 cm brightness of early \HII regions around the first stars. We use outputs from cosmological radiation-hydrodynamics simulations of the formation and...
Takahashi, Ryuichi, Yoshida, Naoki, Takada, Masahiro, Matsubara, Takahiko, Sugiyama, Naoshi, Kayo, Issha, ...
We use 5000 cosmological N-body simulations of 1(Gpc/h)^3 box for the concordance LCDM model in order to study the sampling variances of nonlinear matter power spectrum. We show that the non-Gaussian...
3Department of Astronomy and Physics (2008)
Wayne Hu, Naoshi Sugiyama, Joseph Silk
Cosmic microwave background anisotropies provide a vast amount of cosmological information. Their full physical content and detailed structure can be understood in a simple and intuitive fashion...
Nishimichi, Takahiro, Shirata, Akihito, Taruya, Atsushi, Yahata, Kazuhiro, Saito, Shun, Suto, Yasushi, ...
We use a series of cosmological N-body simulations and various analytic models to study the evolution of the matter power spectrum in real space in a \Lambda Cold Dark Matter universe. We compare the...
Search for a Stochastic Background of 100-MHz GravitationalWaves with Laser Interferometers (2008)
Akutsu, Tomotada, Kawamura, Seiji, Nishizawa, Atsushi, Arai, Koji, Yamamoto, Kazuhiro, Tatsumi, Daisuke, ...
This Letter reports the results of a search for a stochastic background of gravitational waves (GW) at 100 MHz by laser interferometry. We have developed a GW detector, which is a pair of 75-cm...
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...
Tashiro, Hiroyuki, Silk, Joseph, Langer, Mathieu, Sugiyama, Naoshi
The S-Z effect and Faraday rotation from halos are examined over a wide mass range, an including gas condensation and magnetic field evolution. Contributions to the CMB angular power spectrum are...
Constraints on primordial black holes by distortions of the cosmic microwave background (2008)
Tashiro, Hiroyuki, Sugiyama, Naoshi
The possible influence of primordial black hole (PBH) evaporations on cosmic microwave backgrounds (CMB) is investigated. The spectrum distortions of CMB from the blackbody spectrum are described by...
Electromagnetic properties of the early universe (2008)
Takahashi, Keitaro, Ichiki, Kiyotomo, Sugiyama, Naoshi
Detailed physical processes of magnetic field generation from density fluctuations in the prerecombination era are studied. Solving Maxwell equations and the generalized Ohm's law, the evolutions of...
Precision calculations of the gravitational wave background spectrum from inflation (2008)
Kuroyanagi, Sachiko, Chiba, Takeshi, Sugiyama, Naoshi
The spectrum of the gravitational wave background originating from quantum fluctuations during inflation is calculated numerically for various inflation models over a wide range of frequencies. We...
Search for a stochastic background of 100-MHz gravitational waves with laser interferometers (2008)
Akutsu, Tomotada, Kawamura, Seiji, Nishizawa, Atsushi, Arai, Koji, Yamamoto, Kazuhiro, Tatsumi, Daisuke, ...
This letter reports the results of a search for a stochastic background of gravitational waves (GW) at 100 MHz by laser interferometry. We have developed a GW detector, which is a pair of 75-cm...
Simulations of Baryon Acoustic Oscillations I: Growth of Large-Scale Density Fluctuations (2008)
Takahashi, Ryuichi, Yoshida, Naoki, Matsubara, Takahiko, Sugiyama, Naoshi, Kayo, Issha, Nishimichi, Takahiro, ...
We critically examine how well the evolution of large-scale density perturbations is followed in cosmological $N$-body simulations. We first run a large volume simulation and perform a mode-by-mode...
Nishizawa, Atsushi, Kawamura, Seiji, Akutsu, Tomotada, Arai, Koji, Yamamoto, Kazuhiro, Tatsumi, Daisuke, ...
Recently, observational searches for gravitational wave background (GWB) have been developed and given constraints on the energy density of GWB in a broad range of frequencies. These constraints have...
Constraints on Primordial Black Holes by Distortions of Cosmic Microwave Background (2008)
Tashiro, Hiroyuki, Sugiyama, Naoshi
Possible influence of primordial black hole (PBH) evaporations on cosmic microwave background (CMB) is investigated. The spectrum distortions of CMB from the black-body spectrum are described by the...
Nishizawa, Atsushi, Kawamura, Seiji, Akutsu, Tomotada, Arai, Koji, Yamamoto, Kazuhiro, Tatsumi, Daisuke, ...
Recently, observational searches for gravitational wave background (GWB) have been developed and given direct and indirect constraints on the energy density of GWB in a broad range of frequencies....
Ken Gangal, Bharat Ratra, Mark A. Lim, Naoshi Sugiyama, Stacy T. Tanaka
We account for experimental and observational uncertainties in likelihood analyses of cosmic microwave background (CMB) anisotropy data from the MAX 4 and MAX 5 experiments. These analyses use CMB...
Using White Dish CMB Anisotropy Data to Probe Open and Flat-A CDM (2007)
Bharat Ratral, Ken Ganga, Naoshi Sugiyama, G. S. Tucker, J. B. Peterson
We usedata from the White Dish experiment to set limits on cosmic microwave background radiation anisotropies in open and spatially-flat-A cold dark matter cosmogonies. We account for the White Dish...
The Effect of Physical Assumptions on the Calculation of Microwave Background Anisotropies (2007)
Wayne Hu, Douglas Scott, Naoshi Sugiyama, Martin White
this paper, we have set about studying the various assumptions which go into these calculations. For most of the issues, there is a very definite correct choice in order to obtain the most accurate...
Takeshi Chiba, Naoshi Sugiyama, Jun'ichi Yokoyama
Spectra of density perturbations produced during chaotic inflation in scalartensor theories of gravity are calculated, taking both adiabatic and isocurvature modes into account. Comparing the...
Nishizawa, Atsushi J., Komatsu, Eiichiro, Yoshida, Naoki, Takahashi, Ryuichi, Sugiyama, Naoshi
Non-linear evolution of density fluctuations yields secondary anisotropies in the cosmic microwave background (CMB), which are correlated with the same density fluctuations that can be measured by...
Electromagnetic Properties of the Early Universe (2007)
Takahashi, Keitaro, Ichiki, Kiyotomo, Sugiyama, Naoshi
Detailed physical processes of magnetic field generation from density fluctuations in the pre-recombination era are studied. Solving Maxwell equations and the generalized Ohm's law, the evolutions of...
Nishizawa, Atsushi, Kawamura, Seiji, Akutsu, Tomotada, Arai, Koji, Yamamoto, Kazuhiro, Tatsumi, Daisuke, ...
Recently, observational searches for gravitational wave background (GWB) have developed and given direct and indirect constraints on the energy density of GWB in a broad range of frequencies. These...
Analyzing WMAP Observation by Quantum Gravity (2007)
Hamada, Ken-ji, Horata, Shinichi, Sugiyama, Naoshi, Yukawa, Tetsuyuki
The angular power spectra of cosmic microwave background are analyzed under the light of the evolutional scenario of the universe based on the renormalizable quantum theory of gravity in four...
Magnetic Field Spectrum at Cosmological Recombination (2007)
Ichiki, Kiyotomo, Takahashi, Keitaro, Sugiyama, Naoshi, Hanayama, Hidekazu, Ohno, Hiroshi
A generation of magnetic fields from cosmological density perturbations is investigated. In the primordial plasma before cosmological recombination, all of the materials except dark matter in the...
Heating of the Intergalactic Medium by Primordial Miniquasars (2006)
Zaroubi, Saleem, Thomas, Rajat M., Sugiyama, Naoshi, Silk, Joe
A simple analytical model is used to calculate the X-ray heating of the IGM for a range of black hole masses. This process is efficient enough to decouple the spin temperature of the intergalactic...
Probing Primordial Magnetic Fields with the 21cm Fluctuations (2006)
Tashiro, Hiroyuki, Sugiyama, Naoshi
Primordial magnetic fields possibly generated in the very early universe are one of the candidates for the origin of magnetic fields observed in many galaxies and galaxy clusters. After...
Cosmological Magnetic Field: a fossil of density perturbations in the early universe (2006)
Ichiki, Kiyotomo, Takahashi, Keitaro, Ohno, Hiroshi, Hanayama, Hidekazu, Sugiyama, Naoshi
The origin of the substantial magnetic fields that are found in galaxies and on even larger scales, such as in clusters of galaxies, is yet unclear. If the second-order couplings between photons and...
Generation of magnetic field from cosmological perturbations (2006)
Takahashi, Keitaro, Ichiki, Kiyotomo, Ohno, Hiroshi, Hanayama, Hidekazu, Sugiyama, Naoshi
We discuss generation of magnetic field from cosmological perturbations. We consider the evolution of three component plasma (electron, proton and photon) evaluating the collision term between...
The early reionization with the primordial magnetic fields (2005)
Tashiro, Hiroyuki, Sugiyama, Naoshi
The early reionization of the intergalactic medium, which is favored from the WMAP temperature-polarization cross-correlations, contests the validity of the standard scenario of structure formation...
The Epoch of Reionization (2005)
Benson, A. J., Sugiyama, Naoshi, Nusser, Adi, Lacey, C. G.
We have modelled the process of reionization of the IGM by photoionization by galaxies, in order to predict the epoch of reionization. We use a sophisticated semi-analytic model to track the...
Nonlinear Evolution of Cosmic Magnetic Fields and Cosmic Microwave Background Anisotropies (2005)
Tashiro, Hiroyuki, Sugiyama, Naoshi, Banerjee, Robi
In this work we investigate the effects of the primordial magnetic fields on cosmic microwave background anisotropies (CMB). Based on cosmological magnetohydrodynamic (MHD) simulations we calculate...
Inoue, Susumu, Aharonian, Felix A., Sugiyama, Naoshi
Protons can be plausibly accelerated to $\sim 10^{18}$-$10^{19}$ eV in strong accretion shocks surrounding massive clusters of galaxies. Such protons efficiently produce very high energy pairs...
Inoue, Susumu, Aharonian, Felix A., Sugiyama, Naoshi
All sufficiently massive clusters of galaxies are expected to be surrounded by strong accretion shocks, where protons can be accelerated to $\sim 10^{18}$-$10^{19}$ eV under plausible conditions....
Enoki, Motohiro, Inoue, Kaiki T., Nagashima, Masahiro, Sugiyama, Naoshi
We investigate the expected gravitational wave emission from coalescing supermassive black hole (SMBH) binaries resulting from mergers of their host galaxies. We employ a semi-analytic model of...
Classifying the Future of Universes with Dark Energy (2005)
Chiba, Takeshi, Takahashi, Ryuichi, Sugiyama, Naoshi
We classify the future of the universe for general cosmological models including matter and dark energy. If the equation of state of dark energy is less then -1, the age of the universe becomes...
Inoue, Susumu, Aharonian, Felix, Sugiyama, Naoshi
All sufficiently massive clusters of galaxies are expected to be surrounded by strong accretion shocks, where protons can be accelerated to 10181019 eV under plausible conditions. Such protons...
Patchy He II reionization and the physical state of the IGM (2004)
Gleser, Liron, Nusser, Adi, Benson, Andrew J., Ohno, Hiroshi, Sugiyama, Naoshi
We present a Monte-Carlo model of He II reionization by QSOs and its effect on the thermal state of the clumpy intergalactic medium (IGM). The model assumes that patchy reionization develops as a...
Using White Dish CMB Anisotropy Data to Probe Open and Flat-A CDM Cosmogonies (2004)
Ratra, Bharat, Ganga, Ken, Sugiyama, Naoshi, Tucker, G. S., Griffin, G. S., Nguyen, H. T., ...
In this paper we present a similar analysis of the Tucker at al. (1993, hereafter T93) White Dish CMB anisotropy data collected at the South Pole. The white dish detector and telescope are described...
Does Positronium Form in the Universe ? (2004)
Chiba, Takeshi, Sugiyama, Naoshi
Positronium (the bound state of electron and positron) has been thought to be formed after proton decay ($>10^{34}$yr) through collisional recombination and then decays by pair annihilation, thereby...
Enoki, Motohiro, Inoue, Kaiki T., Nagashima, Masahiro, Sugiyama, Naoshi
We investigate the expected gravitational wave emission from coalescing supermassive black hole (SMBH) binaries resulting from mergers of their host galaxies. When galaxies merge, the SMBHs in the...
WMAP constraints on scalar-tensor cosmology and the variation of the gravitational constant (2003)
Nagata, Ryo, Chiba, Takeshi, Sugiyama, Naoshi
We present observational constraints on a scalar-tensor gravity theory by $\chi^2$ test for CMB anisotropy spectrum. We compare the WMAP temperature power spectrum with the harmonic attractor model,...
Isocurvature Fluctuations Induce Early Star Formation (2003)
Sugiyama, Naoshi, Zaroubi, Saleem, Silk, Joseph
The early reionisation of the Universe inferred from the WMAP polarisation results, if confirmed, poses a problem for the hypothesis that scale-invariant adiabatic density fluctuations account for...
Partially ionizing the universe by decaying particles (2003)
Kasuya, S., Kawasaki, M., Sugiyama, Naoshi
We show that UV photons produced by decaying particles can partially reionize the universe and explain the large optical depth observed by Wilkinson Microwave Anisotropy Probe. Together with UV...
Can Non-Gaussian Cosmological Models Explain the WMAP's High Optical Depth for Reionization? (2003)
Chen, Xuelei, Cooray, Asantha, Yoshida, Naoki, Sugiyama, Naoshi
The first-year Wilkinson Microwave Anisotropy Probe data suggest a high optical depth for Thomson scattering of 0.17 +/- 0.04, implying that the universe was reionized at an early epoch, z ~ 20. Such...
The Evolution of Baryon Density Fluctuations in Multi-Component Cosmological Simulations (2003)
Yoshida, Naoki, Sugiyama, Naoshi, Hernquist, Lars
We critically examine how the evolution of the matter density field in cosmological simulations is affected by details of setting up initial conditions. We show that it is non-trivial to realise an...
Simulations of Early Structure Formation: Primordial Gas Clouds (2003)
Yoshida, Naoki, Abel, Tom, Hernquist, Lars, Sugiyama, Naoshi
(abridged) We use large cosmological simulations to study the origin of primordial star-forming clouds in a Lambda CDM universe, by following the formation of dark matter halos and the cooling of gas...
Probing intracluster magnetic fields with cosmic microwave background polarization (2003)
Ohno, Hiroshi, Takada, Masahiro, Dolag, Klaus, Bartelmann, Matthias, Sugiyama, Naoshi
Mukherjee, Pia, Ganga, Ken, Ratra, Bharat, Rocha, Graca, Souradeep, Tarun, Sugiyama, Naoshi, ...
We use joint likelihood analyses of combinations of fifteen cosmic microwave background (CMB) anisotropy data sets from the DMR, UCSB South Pole 1994, Python I--III, ARGO, MAX 4 and 5, White Dish,...
Observational Consequences of Evolution of Primordial Fluctuations in Scalar-Tensor Cosmology (2002)
Nagata, Ryo, Chiba, Takeshi, Sugiyama, Naoshi
Evolution of primordial fluctuations in a Brans-Dicke type scalar-tensor gravity theory is comprehensively investigated. The harmonic attractor model, in which the scalar field has its harmonic...
OVRO CMB Anisotropy Measurement Constraints on Flat-Lambda and Open CDM Cosmogonies (2002)
Mukherjee, Pia, Souradeep, Tarun, Ratra, Bharat, Sugiyama, Naoshi, Górski, Krzysztof M.
We use Owens Valley Radio Observatory (OVRO) cosmic microwave background (CMB) anisotropy data to constrain cosmological parameters. We account for the OVRO beamwidth and calibration uncertainties,...
Statistics of Neutral Regions During Hydrogen Re-Ionization (2002)
Nusser, Adi, Benson, Andrew, Sugiyama, Naoshi, Lacey, Cedric
We present predictions for two statistical measures of the hydrogen reionization process at high redshift. The first statistic is the number of neutral segments identified in spectra of high redshift...
Probing Intracluster Magnetic Fields with Cosmic Microwave Background Polarization (2002)
Ohno, Hiroshi, Takada, Masahiro, Dolag, Klaus, Bartelmann, Matthias, Sugiyama, Naoshi
Intracluster magnetic fields with $ \sim \mu G $ strength induce Faraday rotation on the cosmic microwave background (CMB) polarization. Measurements of this effect can potentially probe the detailed...
How large is our universe? (2002)
Inoue, Kaiki Taro, Sugiyama, Naoshi
We reexamine constraints on the spatial size of closed toroidal models with cold dark matter and the cosmological constant from cosmic microwave background. We carry out Bayesian analyses using the...
Takada, Masahiro, Ohno, Hiroshi, Sugiyama, Naoshi
The observed magnetic field of microgauss strength in clusters of galaxies should induce the Faraday rotation effect on the linearly polarized cosmic microwave background (CMB) radiation when the CMB...
Takada, Masahiro, Sugiyama, Naoshi
We investigate a cross-correlation between the weak gravitational lensing field of the large-scale structure, $\kappa$, and the secondary temperature fluctuation field, $\Delta$, of cosmic microwave...
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...
Polarization of the Cosmic Microwave Background from Non-Uniform Reionization (2001)
Liu, Guo-Chin, Sugiyama, Naoshi, Benson, Andrew J., Lacey, C. G., Nusser, Adi
We study the signal in the Cosmic Microwave Background (CMB) polarization anisotropy resulting from patchy reionization. It is well known that the primordial polarization of the CMB is very sensitive...
Double Inflation in Supergravity and the Boomerang Observations (2000)
Kanazawa, Toshiyuki, Kawasaki, Masahiro, Sugiyama, Naoshi, Yanagida, T.
One of the biggest mystery of the recent observation of cosmic microwave background anisotropies by the boomerang team is insignificance of the second acoustic peak in the angular power spectrum. It...
Nonlinear Evolution of Very Small Scale Cosmological Baryon Perturbations at Recombination (2000)
Liu, Guo-Chin, Yamamoto, Kazuhiro, Sugiyama, Naoshi, Nishioka, Hiroaki
The evolution of baryon density perturbations on very small scales is investigated. In particular, the nonlinear growth induced by the radiation drag force from the shear velocity field on larger...
Non-uniform reionization by galaxies and its effect on the cosmic microwave backgroun (2000)
Benson, A. J., Nusser, Adi, Sugiyama, Naoshi, Lacey, C. G.
We present predictions for the reionization of the intergalactic medium by stars in high-redshift galaxies. We calculate ionizing luminosities of galaxies, including the effects of absorption by...
MeV-scale Reheating Temperature and Thermalization of Neutrino Background (2000)
Kawasaki, M., Kohri, K., Sugiyama, Naoshi
The late-time entropy production by the massive particle decay induces the various cosmological effects in the early epoch and modify the standard scenario. We investigate the thermalization process...
Limits on Neutrino Mass from Cosmic Structure Formation (1999)
Fukugita, Masataka, Liu, Guo-Chin, Sugiyama, Naoshi
We consider the effect of three species of neutrinos with nearly degenerate mass on the cosmic structure formation in a low matter-density universe within a hierarchical clustering scenario with a...
Double Inflation in Supergravity and the Large Scale Structure (1999)
Kanazawa, Toshiyuki, Kawasaki, M., Sugiyama, Naoshi, Yanagida, T.
The cosmological implication of a double inflation model with hybrid + new inflations in supergravity is studied. The hybrid inflation drives an inflaton for new inflation close to the origin through...
Temperature correlations in a compact hyperbolic universe (1999)
Inoue, Kaiki Taro, Tomita, Kenji, Sugiyama, Naoshi
The effect of a non-trivial topology on the temperature correlations on the cosmic microwave background (CMB) in a small compact hyperbolic universe with volume comparable to the cube of the...
Rocha, Graca, Stompor, Radoslaw, Ganga, Ken, Ratra, Bharat, Platt, Stephen R., Sugiyama, Naoshi, ...
We use Python I, II, and III cosmic microwave background anisotropy data to constrain cosmogonies. We account for the Python beamwidth and calibration uncertainties. We consider open and...
The Sunyaev-Zel'dovich Effect by Cocoons of Radio Galaxies (1999)
Yamada, Masako, Sugiyama, Naoshi, Silk, Joseph
We estimate the deformation of the cosmic microwave background radiation by the hot region (``cocoon'') around a radio galaxy. A simple model is adopted for cocoon evolution while the jet is on, and...
Ratra, Bharat, Stompor, Radoslaw, Ganga, Ken, Rocha, Graca, Sugiyama, Naoshi, Gorski, Krzysztof M.
We use combinations of ten small-scale cosmic microwave background anisotropy data sets from the UCSB South Pole 1994, ARGO, MAX 4 and 5, White Dish and SuZIE experiments to constrain cosmogonies. We...
Graça Rocha, Radoslaw Stompor, Ken Ganga, Bharat Ratra, Stephen R. Platt, Naoshi Sugiyama, ...
We use Python I, II, and III cosmic microwave background anisotropy data to constrain cosmogonies. We account for the Python beamwidth and calibration uncertainties. We consider open and...
Cosmological Constraints on Late-time Entropy Production (1998)
Kawasaki, M., Kohri, K., Sugiyama, Naoshi
We investigate cosmological effects concerning the late-time entropy production due to the decay of non-relativistic massive particles. The thermalization process of neutrinos after the entropy...
ARGO CMB Anisotropy Measurement Constraints on Open and Flat-Lambda CDM Cosmogonies (1998)
Ratra, Bharat, Ganga, Ken, Stompor, Radoslaw, Sugiyama, Naoshi, De Bernardis, Paolo, Gorski, Krzysztof M.
We use data from the ARGO cosmic microwave background (CMB) anisotropy experiment to constrain cosmogonies. We account for the ARGO beamwidth and calibration uncertainties, and marginalize over the...
Small-Scale Fluctuations in Cosmic X-ray Background : A Power Spectrum Approach (1998)
Yamamoto, Kazuhiro, Sugiyama, Naoshi
Equations to investigate fluctuations in cosmic X-ray background radiation due to point-like sources at high-redshift are formulated in a systematic way. The angular power spectrum of X-ray...
Observational tests of x-matter models (1998)
Chiba, Takeshi, Sugiyama, Naoshi, Nakamura, Takashi
We study gravitational lensing statistics, matter power spectra and the angular power spectra of the cosmic microwave background (CMB) radiation in x-matter models. We adopt an equation-of-state of...
Observational Implications of Axionic Isocurvature Fluctuations (1998)
Kanazawa, Toshiyuki, Kawasaki, M., Sugiyama, Naoshi, Yanagida, T.
The axion is the most attractive candidate to solve the strong CP problem in QCD. If it exists, the inflationary universe produces axion fluctuations which are mixtures of isocurvature and adiabatic...
Isocurvature Fluctuations of the M-theory Axion in a Hybrid Inflation Model (1998)
Kanazawa, Toshiyuki, Kawasaki, M., Sugiyama, Naoshi, Yanagida, T.
The M-theory, the strong-coupling heterotic string theory, presents various interesting new phenomenologies. The M-theory bulk axion is one of these. The decay constant in this context is estimated...
Ucsb South Pole, Radoslaw Stompor, White Dish, Suzie Data, Ken Ganga, ...
We use combinations of ten small-scale cosmic microwave background anisotropy data sets from the UCSB South Pole 1994, ARGO, MAX 4 and 5, White Dish and SuZIE experiments to constrain cosmogonies. We...
Theoretical View of Anisotropies of Cosmic Microwave Background (1998)
. Cosmic Microwave Background (CMB) anisotropies have been recognized as one of the most important observational quantities to understand the early stage of our universe. In this paper, recent...
Effect of Void Network on CMB Anisotropy (1997)
Sakai, Nobuyuki, Sugiyama, Naoshi, Yokoyama, Jun'ichi
We study the effect of a void network on the CMB anisotropy in the Einstein-de Sitter background using Thompson &Vishniac's model. We consider comprehensively the Sacks-Wolfe effect, the Rees-Sciama...
CMB Anisotropy Correlation Function and Topology from Simulated Maps for MAP (1997)
Park, Changbom, Colley, Wesley N., Gott III, J. Richard, Ratra, Bharat, Spergel, David N., Sugiyama, Naoshi
We have simulated cosmic microwave background (CMB) anisotropy maps for several COBE-DMR-normalized cold dark matter (CDM) cosmogonies, to make predictions for the upcoming MAP experiment. We have...
Evolution of Small Scale Cosmological Baryon Perturbations and Matter Transfer Functions (1997)
Yamamoto, Kazuhiro, Sugiyama, Naoshi, Sato, Humitaka
The evolution of small scale cosmological perturbations is carefully re-examined. Through the interaction with photons via electrons, baryon perturbations show interesting behavior in some physical...
Cosmological Baryon Sound Waves Coupled with the Primeval Radiation (1997)
Yamamoto, Kazuhiro, Sugiyama, Naoshi, Sato, Humitaka
The fluid equations for the baryon-electron system in an expanding universe are derived from the Boltzmann equation. The effect of the Compton interaction is taken into account properly in order to...
Ganga, Ken, Ratra, Bharat, Lim, Mark A., Sugiyama, Naoshi, Tanaka, Stacy T.
We account for experimental and observational uncertainties in likelihood analyses of cosmic microwave background (CMB) anisotropy data from the MAX 4 and MAX 5 experiments. These analyses use CMB...
Imprints of the Metrically-coupled Dilaton on Density Perturbations in Inflationary Cosmology (1997)
Chiba, Takeshi, Sugiyama, Naoshi, Yokoyama, Jun'ichi
Spectra of density perturbations produced during chaotic inflation are calculated, taking both adiabatic and isocurvature modes into account in a class of scalar-tensor theories of gravity in which...
Cosmology with x-matter (1997)
Chiba, Takeshi, Sugiyama, Naoshi, Nakamura, Takashi
Motivated by the possibility of $H_0t_0 > 1$ where $H_0$ and $t_0$ are the Hubble parameter and the age of the universe, respectively, we investigate the cosmology including x-matter. x-matter is...
Ganga, K., Ratra, Bharat, Church, S. E., Sugiyama, Naoshi, Ade, P. A. R., Holzapfel, W. L., ...
We use arcminute-scale data from the Sunyaev-Zel'dovich Infrared Experiment to set limits on anisotropies in the cosmic microwave background radiation in open and spatially-flat-Lambda cold dark...
The Physics of Microwave Background Anisotropies (1996)
Hu, Wayne, Sugiyama, Naoshi, Silk, Joseph
Cosmic microwave background anisotropies provide a vast amount of cosmological information. Their full physical content and detailed structure can be understood in a simple and intuitive fashion...
CMB radiation power spectrum in CDM open universes up to 2nd order perturbations (1996)
Sanz, Jose L., Martinez-Gonzalez, Enrique, Cayon, Laura, Silk, Joseph, Sugiyama, Naoshi
A second--order perturbation theory approach is developed to calculate temperature anisotropies in the cosmic microwave background. Results are given for open universes and fluctuations corresponding...
Ganga, Ken, Ratra, Bharat, Gundersen, Josh, Sugiyama, Naoshi
We develop methods to account for experimental and observational uncertainties in likelihood analyses of data from cosmic microwave background (CMB) anisotropy experiments and apply them to an...
Ganga, Ken, Ratra, Bharat, Sugiyama, Naoshi
Goodness-of-fit statistics are used to quantitatively establish the compatibility of CMB anisotropy predictions in a wide range of DMR-normalized, open and spatially-flat $\Lambda$, CDM cosmogonies...
CMB Anisotropy in COBE-DMR-Normalized Flat $\Lambda$ CDM Cosmogony (1995)
Ratra, Bharat, Sugiyama, Naoshi
We compute the cosmic microwave background (CMB) anisotropy in a low-density, flat, cosmological constant, cold dark matter model which is normalized to the two-year COBE DMR sky map. Although...
CMB Anisotropy in COBE-DMR-Normalized Open CDM Cosmogony (1995)
Ratra, Bharat, Banday, Anthony J., Gorski, Krzysztof M., Sugiyama, Naoshi
We compute the CMB anisotropy in an open inflation CDM model which is normalized to the two-year DMR sky map. Presently available CMB data is consistent with $\Omega_0 \sim 0.3 - 0.4$, but does not...
Kawasaki, M., Sugiyama, Naoshi, Yanagida, T.
In the chaotic inflation models, quantum fluctuations for axion fields lead to the overproduction of domain walls and too large isocurvature fluctuations which is inconsistent with the observations...
Small Scale Cosmological Perturbations: An Analytic Approach (1995)
Through analytic techniques verified by numerical calculations, we establish general relations between the matter and cosmic microwave background (CMB) power spectra and their dependence on...
The Effect of Physical Assumptions on the Calculation of Microwave Background Anisotropies (1995)
Hu, Wayne, Scott, Douglas, Sugiyama, Naoshi, White, Martin
As the data on CMB anisotropies improve and potential cosmological applications are realized, it will be increasingly important for theoretical calculations to be as accurate as possible. All modern...
The Physics of Microwave Background Anisotropies (1995)
Hu, Wayne, Sugiyama, Naoshi, Silk, Joseph
Cosmic microwave background anisotropies provide a vast amount of information on both structure formation in the universe and the background dynamics and geometry. The full physical content and...
COBE-DMR-normalised Open Inflation, CDM Cosmogony (1995)
Gorski, Krzysztof M., Ratra, Bharat, Sugiyama, Naoshi, Banday, Anthony J.
Fourier analysis on a cut sky of the two-year COBE DMR 53 and 90 GHz sky maps (in galactic coordinates) is used to determine the normalisation of an open inflation model based on the cold dark matter...
COBE Constraints on Baryon Isocurvature Models (1995)
Hu, Wayne, Bunn, Emory F., Sugiyama, Naoshi
We consider Bayesian constraints on standard isocurvature baryon models from the slope and normalization of the anisotropy power spectrum detected by the COBE DMR experiment in their two year maps....
Through analytic techniques veriÐed by numerical calculations, we establish general relations between the matter and cosmic microwave background (CMB) power spectra and their dependence on...
Cosmic Background Anisotropies in CDM Cosmology (1994)
Cosmic microwave background (CMB) anisotropies and density fluctuations are calculated for flat cold dark matter (CDM) models with a wide range of parameters, i.e., $\Omega_0, h$ and $\Omega_B$ for...
Toward Understanding CMB Anisotropies and Their Implications (1994)
Working toward a model independent understanding of cosmic microwave background (CMB) anisotropies and their significance, we undertake a comprehensive and self-contained study of scalar perturbation...
Anisotropies in the Cosmic Microwave Background: An Analytic Approach (1994)
We introduce a simple yet powerful {\it analytic} method which obtains the structure of cosmic microwave background anisotropies to better than 5-10\% in temperature fluctuations on {\it all} scales....
Cosmological-Constant Cold Dark Matter Models and the COBE Two-Year Sky maps (1994)
Bunn, Emory F., Sugiyama, Naoshi
We compare the two-year COBE DMR sky maps with the predictions of cosmological-constant cold dark matter models. Using a Bayesian analysis, we find that the most likely value of the cosmological...
CBR Anisotropy in an Open Inflation, CDM Cosmogony (1994)
Kamionkowski, Marc, Ratra, Bharat, Spergel, David N., Sugiyama, Naoshi
We compute the cosmic background radiation anisotropy, produced by energy-density fluctuations generated during an early epoch of inflation, in an open cosmological model based on the cold dark...
The Imprint of $\Omega$ on the Cosmic Microwave Background (1994)
Sugiyama, Naoshi, Silk, Joseph
We investigate the dependence of large angular scale cosmic microwave background anisotropies on various initial conditions, including both adiabatic and isocurvature perturbations and the initial...
Thermal History Constraints on the Isocurvature Baryon Model (1994)
We present a thorough and detailed investigation of baryon isocurvature models including realistic thermal histories, \ie, late or partial reionization of the universe and compact object formation...
Microwave Background Fluctuations in an Open Universe (1994)
Spergel, David N., Pen, Ue-Li, Kamionkowski, Marc, Sugiyama, Naoshi
( to appear in: Proceedings of the Nishonomiya Yukawa Memorial Symposium Edited by M. Sasaki) There are several models for generating fluctuations in an open universe that are compatible with the...
Kamionkowski, Marc, Spergel, David N., Sugiyama, Naoshi
We perform detailed calculations of cosmic microwave background (CMB) anisotropies in a CDM-dominated open universe with primordial adiabatic density perturbations for a variety of reionization...
Chiba, Takashi, Sugiyama, Naoshi, Suto, Yasushi
We have performed the most comprehensive predictions of the temperature fluctuations \dtt in the primeval isocurvature baryon models to see whether or not the models are consistent with the recent...
Reionization and Cosmic Microwave Anisotropies (1993)
Sugiyama, Naoshi, Silk, Joseph, Vittorio, Nicola
The effects of reionization, occurring after standard recombination in cold dark matter-dominated models, on CMB anisotropies are investigated. Late-time reionization reduces the CMB anisotropies, in...
The Small Scale Integrated Sachs-Wolfe Effect (1993)
The integrated Sachs-Wolfe effect (ISW) can be an important factor in the generation of Cosmic Microwave Background anisotropies on all scales, especially in a reionized curvature or lambda dominated...
CMB Anisotropy Correlation Function and Topology from Simulated Maps for MAP (1469)
Changbom Park, Wesley N. Colley, J. Richard, Gott Iii, Bharat Ratra, David N, ...
We have simulated cosmic microwave background (CMB) anisotropy maps for several COBE-DMR-normalized cold dark matter (CDM) cosmogonies, to make predictions for the MAP experiment, an upcoming...
Nonlinear Evolution of Very Small Scale Cosmological Baryon Perturbations at Recombination.
Liu, Guo-Chin, Yamamoto, Kazuhiro, Sugiyama, Naoshi, Nishioka, Hiroaki
The evolution of baryon density perturbations on very small scales is investigated. In particular, the nonlinear growth induced by the radiation drag force from the shear velocity field on larger...
Nonlinear Evolution of Very Small Scale Cosmological Baryon Perturbations at Recombination.
Liu, Guo-Chin, Yamamoto, Kazuhiro, Sugiyama, Naoshi, Nishioka, Hiroaki
The evolution of baryon density perturbations on very small scales is investigated. In particular, the nonlinear growth induced by the radiation drag force from the shear velocity field on larger...