Nagashima, Masahiro, Yahagi, Hideki, Enoki, Motohiro, Yoshii, Yuzuru, Gouda, Naoteru
We construct the Numerical Galaxy Catalog ($\nu$GC), based on a semi-analytic model of galaxy formation combined with high-resolution N-body simulations in a $\Lambda$-dominated flat cold dark matter...
Chemical Enrichment in Damped Lyman Alpha Systems From Hierarchical Galaxy Formation Models (2003)
Okoshi, Katsuya, Nagashima, Masahiro, Gouda, Naoteru, Yoshioka, Satoshi
We investigate chemical enrichment in Damped Lyman alpha (DLA) systems in the hierarchical structure formation scenario using a semi-analytic model of galaxy formation. The model developed by...
Universality in the distribution of caustics in the expanding Universe (2003)
Yano, Taihei, Koyama, Hiroko, Buchert, Thomas, Gouda, Naoteru
We numerically investigate the long--time evolution of density perturbations after the first appearance of caustics in an expanding cosmological model with one--dimensional `single--wave' initial...
Relations Between Environments of Quasars and Galaxy Formation (2002)
Enoki, Motohiro, Nagashima, Masahiro, Gouda, Naoteru
We investigate the environments of quasars such as number distribution of galaxies using a semi-analytic model which includes both galaxy and quasar formations based on the hierarchical clustering...
Stellar Kinematics of the Spiral Structure in the Solar Neighborhood (2000)
Yano, Taihei, Chiba, Masashi, Gouda, Naoteru
We present a method, based on the kinematic analysis of the Galactic disk stars, to clarify whether the internal motions of the stellar system in spiral arms follow those expected in the density wave...
Fujita, Yutaka, Nagashima, Masahiro, Gouda, Naoteru
In order to constrain parameters in galaxy formation theories, especially those for a star formation process, we investigate cold gas in elliptical galaxies. We calculate the detection rate of cold...
A Universal Profile of the Dark Matter Halo and the Two-point Correlation Function (1999)
We have investigated the relation between the two-point spatial correlation function and the density profile of the dark matter halo in the strongly non-linear regime. It is well known that when the...
Nagashima, Masahiro, Gouda, Naoteru
We examined the physical origin of the colour-magnitude relation of elliptical galaxies in clusters of galaxies in the hierarchical clustering scenario by using a semi-analytic model of galaxy...
Tsuchiya, Toshio, Gouda, Naoteru
The relation between relaxation, the time scale of Lyapunov instabilities, and the Kolmogorov-Sinai time in a one-dimensional gravitating sheet system is studied. Both the maximum Lyapunov exponent...
We have investigated time evolutions of power spectra of density fluctuations for long time after the first appearance of caustics in the expanding one-dimensional universe. It is found that when an...
Effects of the UV background radiation on galaxy formation (1998)
Nagashima, Masahiro, Gouda, Naoteru, Sugiura, Norimasa
We investigate the effects of the UV background radiation on galaxy formation by using the semi-analytic model including the photoionization process. The semi-analytic model is based on Cole et al....
Effects of Merging Histories on Angular Momentum Distribution of Dark Matter Haloes (1997)
Nagashima, Masahiro, Gouda, Naoteru
The effects of merging histories of proto-objects on the angular momentum distributions of the present-time dark matter haloes are analysed. An analytical approach to the analysis of the angular...
We investigate stability of the scale-invariant solutions of the BBGKY equations for two-point spatial correlation functions of the density fluctuations in the strongly non-linear regime. In the case...
Chaotic itinerancy and thermalization in one-dimensional self-gravitating systems (1996)
Tsuchiya, Toshio, Gouda, Naoteru, Konishi, Tetsuro
This is the third paper of the series of our studies of the one-dimensional self-gravitating many-body systems. In this paper, we thus study the transition phenomena after the first transition from a...
The Effect of Spatial Correlations on Merger Trees of Dark Matter Haloes (1996)
Nagashima, Masahiro, Gouda, Naoteru
The effects of spatial correlations of density fluctuations on merger histories of dark matter haloes (so-called `{\it merger trees}') are analysed. We compare the mass functions of dark haloes...
We have investigated the scale-invariant solutions of the BBGKY equations for spatial correlation functions of cosmological density fluctuations and the mean relative peculiar velocity in the...
The pseudo-spectral method is proposed for following the evolution of density and velocity fluctuations at the weakly non-linear stage in the expanding universe with a good accuracy. In this method,...
Relaxation processes in one-dimensional self-gravitating many-body systems (1995)
Tsuchiya, Toshio, Gouda, Naoteru, Konishi, Tetsuro
Though one dimensional self-gravitating $N$-body systems have been studied for three decade, the nature of relaxation was still unclear. There were inconsistent results about relaxation time; some...
Hubble Parameter in Void Universe (1995)
Nakao, Ken-ichi, Gouda, Naoteru, Chiba, Takeshi, Ikeuchi, Satoru, Nakamura, Takashi, Shibata, Masaru
We investigate the distance-redshift relation in the simple void model. As discussed by Moffat and Tatarski, if the observer stays at the center of the void, the observed Hubble parameter is not so...
Quasi-equilibria in one-dimensional self-gravitating many body systems (1994)
Tsuchiya, Toshio, Konishi, Tetsuro, Gouda, Naoteru
The microscopic dynamics of one-dimensional self-gravitating many-body systems is studied. We examine two courses of the evolution which has the isothermal and stationary water-bag distribution as...