109 research outputs found
Thermodynamics of a two-dimensional Yukawa fluid
Thermodynamic quantities of a two-dimensional Yukawa system, a model for various systems including single-layered dust particles observed in dusty plasmas, are obtained and expressed by simple interpolation formulas. In the domain of weak coupling, the analytical method based on the cluster expansion is applied and, in the domain of intermediate and strong coupling, numerical simulations are performed. Due to reduced dimensionality, the treatment based on the mean field fails at the short range and exact behavior of the binary correlation is to be taken into account even in the case of weak coupling.</p
Nonlinear Evolution of the Genus Statistics with Zel'dovich Approximation
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 invariant manner. It is shown that
normalized genus density does not depend on the initial spectral shape but is a
function of the fluctuation amplitude only.Comment: 21 pages, 6 Postscript figures, LaTe
The Galaxy Distribution Function from the 2MASS Survey
We determine the spatial distribution function of galaxies from a wide range
of samples in the 2MASS survey. The results agree very well with the form of
the distribution predicted by the theory of cosmological gravitational
many-body galaxy clustering. On large scales we find a value of the clustering
parameter b = 0.867 +/- 0.026, in agreement with b = 0.83 +/- 0.05 found
previously for the Pisces-Perseus supercluster. We measure b(theta) as a
function of scale, since this is a powerful test of the applicability of
computer simulations. The results suggest that when galaxies clustered they
were usually surrounded by individual, rather than by communal haloes.Comment: Astrophysical Journal, accepted: 14 pages with 23 embedded reduced
resolution Postscript figures & 2 table
Clustering of Lyman alpha emitters at z ~ 4.5
We present the clustering properties of 151 Lyman alpha emitting galaxies at
z ~ 4.5 selected from the Large Area Lyman Alpha (LALA) survey. Our catalog
covers an area of 36' x 36' observed with five narrowband filters. We assume
that the angular correlation function w(theta) is well represented by a power
law A_w = Theta^(-beta) with slope beta = 0.8, and we find A_w = 6.73 +/- 1.80.
We then calculate the correlation length r_0 of the real-space two-point
correlation function xi(r) = (r/r_0)^(-1.8) from A_w through the Limber
transformation, assuming a flat, Lambda-dominated universe. Neglecting
contamination, we find r_0 = 3.20 +/- 0.42 Mpc/h. Taking into account a
possible 28% contamination by randomly distributed sources, we find r_0 = 4.61
+/- 0.6 Mpc/h. We compare these results with the expectations for the
clustering of dark matter halos at this redshift in a Cold Dark Matter model,
and find that the measured clustering strength can be reproduced if these
objects reside in halos with a minimum mass of 1-2 times 10^11 Solar masses/h.
Our estimated correlation length implies a bias of b ~ 3.7, similar to that of
Lyman-break galaxies (LBG) at z ~ 3.8-4.9. However, Lyman alpha emitters are a
factor of ~ 2-16 rarer than LBGs with a similar bias value and implied host
halo mass. Therefore, one plausible scenario seems to be that Lyman alpha
emitters occupy host halos of roughly the same mass as LBGs, but shine with a
relatively low duty cycle of 6-50%.Comment: 23 pages in preprint format, 4 figures, ApJ accepte
Hierarchical clustering and formation of power-law correlation in 1-dimensional self-gravitating system
The process of formation of fractal structure in one-dimensional
self-gravitating system is examined numerically. It is clarified that
structures created in small spatial scale grow up to larger scale through
clustering of clusters, and form power-law correlation.Comment: 9pages,4figure
Phases in Strongly Coupled Electronic Bilayer Liquids
The strongly correlated liquid state of a bilayer of charged particles has
been studied via the HNC calculation of the two-body functions. We report the
first time emergence of a series of structural phases, identified through the
behavior of the two-body functions.Comment: 5 pages, RevTEX 3.0, 4 ps figures; Submitted to Phys. Rev. Let
Primordial fractal density perturbations and structure formation in the Universe: 1-Dimensional collisionless sheet model
Two-point correlation function of galaxy distribution shows that the
structure in the present Universe is scale-free up to a certain scale (at least
several tens Mpc), which suggests that a fractal structure may exist. If small
primordial density fluctuations have a fractal structure, the present
fractal-like nonlinear structure below the horizon scale could be naturally
explained. We analyze the time evolution of fractal density perturbations in
Einstein-de Sitter universe, and study how the perturbation evolves and what
kind of nonlinear structure will come out. We assume a one-dimensional
collisionless sheet model with initial Cantor-type fractal perturbations. The
nonlinear structure seems to approach some attractor with a unique fractal
dimension, which is independent of the fractal dimensions of initial
perturbations. A discrete self-similarity in the phase space is also found when
the universal nonlinear fractal structure is reached.Comment: 17 pages, 19 jpeg figures. Accepted for publication in ApJ. Figures
are also available from
http://www.phys.waseda.ac.jp/gravity/~tatekawa/0003124/figs.tar.g
The Correlation Function in Redshift Space: General Formula with Wide-angle Effects and Cosmological Distortions
A general formula for the correlation function in redshift space is derived
in linear theory. The formula simultaneously includes wide-angle effects and
cosmological distortions. The formula is applicable to any pair with arbitrary
angle between lines of sight, and arbitrary redshifts, , ,
which are not necessarily small. The effects of the spatial curvature both on
geometry and on fluctuation spectrum are properly taken into account, and thus
our formula holds in a Friedman-Lema\^{\i}tre universe with arbitrary
cosmological parameters and . We illustrate the pattern
of the resulting correlation function with several models, and also show that
validity region of the conventional distant observer approximation is .Comment: 45 pages including 9 figures, To Appear in Astrophys. J. 535 (2000
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