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Figure 1:
A historical time-line showing the
major evolutionary stages of our Universe
according
to the standard model, from the
earliest moments of the Planck era to the present. The
horizontal
axis represents logarithmic time in
seconds (or equivalently energy in electron-Volts or
temperature in
Kelvin), and the solid red line
roughly models the radius of the Universe, showing the
different rates
of expansion at different times:
exponential during inflation, shallow power law during
the radiation
dominated era, and a somewhat
steeper power law during the current matter dominated
phase.
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Figure 2:
Schematic depicting the general
sequence of events in the post-recombination
Universe.
The solid and dotted lines
potentially track the Jeans mass of the average baryonic
gas component
from the recombination epoch
at
to the current time. A residual
ionization fraction
of
following recombination allows for
Compton interactions with photons to
, during which the Jeans mass
remains constant at
. The Jeans mass then
decreases as the Universe expands
adiabatically until the first collapsed structures form
sufficient
amounts of hydrogen molecules to
trigger a cooling instability and produce pop
III stars at
.
Star formation activity can then
reheat the Universe and raise the mean Jeans mass to
above
. This reheating could affect the
subsequent development of structures such as galaxies
and
the observed Ly
clouds.
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Figure 3:
Contour plot of the Bianchi type IX
potential
, where
are the anisotropy canonical
coordinates. Seven level surfaces
are shown at equally spaced decades ranging from
to
.
For large isocontours (
), the potential is open and
exhibits a strong triangular symmetry
with three narrow channels
extending to spatial infinity. For
, the potential closes and
is
approximately circular for
.
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Figure 4:
Fractal structure of the transition
between reflected and captured states for
colliding
kink-antikink solitons in the
parameter space of impact velocity for a
scalar field
potential. The top image (a) shows
the 2-bounce windows in dark with the rightmost
region
(
) representing the single-bounce
regime above which no captured state exists, and
the
leftmost white region (
) representing the captured state
below which no reflection windows
exist. Between these two marker
velocities, there are 2-bounce reflection states of
decreasing widths
separated by regions of bion
formation. Zooming in on the domain outlined by the
dashed box, a
self-similar structure is apparent
in the middle image (b), where now the dark regions
represent
3-bounce windows of decreasing
widths. Zooming in once again on the boundaries of these
3-bounce
windows, a similar structure is
found as shown in the bottom image (c) but with 4-bounce
reflection
windows. This pattern of
self-similarity characterized by
-bounce windows is observed at all
scales
investigated numerically.
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Figure 5:
Image sequence of the scalar field
from a 2D calculation showing the interaction of
two
deflagration systems (one planar
wall propagating from the right side, and one spherical
bubble
nucleating from the center). The
physical size of the grid is set to
and resolved
by
zones. The run time of the
simulation is about two sound crossing times, where
the
sound speed is
, so the shock fronts leading the
condensing phase fronts travel across the grid
twice. The hot quark (cold hadron)
phases have smaller (larger) scalar field values and are
represented
by black (color) in the
colormap.
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Figure 6:
Image sequence of the scalar field
from a 2D calculation showing the interaction of
two detonation systems (one planar
wall propagating from the right side, and one spherical
bubble
nucleating from the center). The
physical size of the grid is set to
and resolved by
zones. The run time of the
simulation is about two sound crossing times.
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Figure 7:
Image sequence of the scalar field
from a 2D calculation showing the interaction of
shock
and rarefaction waves with a
deflagration wall (initiated at the left side) and a
detonation wall
(starting from the right). A shock
and rarefaction wave travel to the right and left,
respectively, from
the temperature discontinuity
located initially at the grid center (the right half of
the grid is at a
higher temperature). The physical
size of the domain is set to
and resolved by
zones. The run time of the
simulation is about two sound crossing times.
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Figure 8:
Historical time-line of the cosmic
microwave background radiation showing the start
of
photon/nuclei combination, the
surface of last scattering (SoLS), and the epoch of
reionization due
to early star formation. The times
are represented in years (to the right) and redshift (to
the left).
Primary anisotropies are
collectively attributed to the early effects at the last
scattering surface and the
large scale Sachs-Wolfe effect.
Secondary anisotropies arise from path integration
effects, reionization
smearing, and higher order
interactions with the evolving nonlinear structures at
relatively low
redshifts.
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Figure 9:
Temperature fluctuations (
) in the CMBR due to the primary
Sachs-Wolfe
(SW) effect and secondary
integrated SW, Doppler, and Thomson scattering effects in
a critically
closed model. The top two plates
are results with no reionization and baryon fractions
0.02 (plate
1,
,
), and 0.2 (plate 2,
,
).
The bottom two plates are results
from an ”early and gradual” reionization scenario of
decaying
neutrinos with baryon fraction 0.02
(plate 3,
,
; and plate 4,
,
). If reionization occurs, the
scattering probability increases and
anisotropies are damped with each
scattering event. At the same time, matter structures
develop large
bulk motions relative to the
comoving background and induce Doppler shifts on the CMB.
The imprint
of this effect from last scattering
can be a significant fraction of primary
anisotropies.
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Figure 10:
Secondary anisotropies from the
proper motion of galaxy clusters across the sky
and Rees-Sciama effects are
presented in the upper-left image over
in a critically
closed Cold Dark Matter model. The
corresponding column density of matter over the
same
region (
,
) is displayed in the upper-right,
clearly showing the dipolar
nature of the proper motion effect.
Anisotropies arising from decaying potentials in an
open
model over a scale of
are shown in the bottom left image,
along with
the gravitational potential over
the same region (
,
) in the bottom right,
demonstrating a clear
anti-correlation. Maximum temperature fluctuations in
each simulation are
respectvely. Secondary anisotropies
are dominated by decaying
potentials at large scales, but all
three sources (decaying potential, proper motion, and
R-S) produce
signatures of order
.
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Figure 11:
Distribution of the gas density at
redshift
from a numerical
hydrodynamics
simulation of the Ly
forest with a CDM spectrum
normalized to second year COBE observations,
Hubble parameter of
, a comoving box size of
, and baryonic density of
composed of 76% hydrogen and 24%
helium. The region shown is 2.4
Mpc (proper) on a
side. The isosurfaces represent
baryons at ten times the mean density and are color coded
to the gas
temperature (dark blue
, light blue
). The higher density contours
trace
out isolated spherical structures
typically found at the intersections of the filaments. A
single random
slice through the cube is also
shown, with the baryonic overdensity represented by a
rainbow-like color
map changing from black (minimum)
to red (maximum). The
mass fraction is shown with
a
wire mesh in this same slice. To
emphasize fine structure in the minivoids, the mass
fraction in the
overdense regions has been rescaled
by the gas overdensity wherever it exceeds unity.
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Figure 12:
Two different model simulations of
cosmological sheets are presented: a six species
model
including only atomic line cooling
(left), and a nine species model including also hydrogen
molecules
(right). The evolution sequences in
the images show the baryonic overdensity and gas
temperature at
three redshifts following the
initial collapse at
. In each figure, the vertical axis
is
long (parallel to the plane of
collapse) and the horizontal axis extends to
on a logarithmic
scale to emphasize the central
structures. Differences in the two cases are observed in
the cold pancake
layer and the cooling flows between
the shock front and the cold central layer. When the
central layer
fragments, the thickness of the
cold gas layer in the six (nine) species case grows
to
and
the surface density evolves with a
dominant transverse mode corresponding to a scale of
approximately
. Assuming a symmetric distribution
of matter along the second transverse direction,
the
fragment masses are
approximately
(
) solar masses.
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