The nature of the observed cosmic acceleration is one of
the most puzzling and fascinating issues of cosmology. We have chosen
to investigate the nature of dark energy through the weak lensing of
the Cosmic Microwave Background, which we regard as a most suitable
tool due to its being especially sensitive to the dynamics at the onset
of the acceleration. We have extended the theory of weak lensing to a
wide class of models beyond the concordance \Lambda CDM one, thus
including as sources of acceleration both quintessence scalar fields,
modifications of Einstein-Hilbert gravity or a combinations of the two,
and we have set up a numerical code generating the fully lensed spectra
of the CMB in all these scenarios. We show how these models give raise
to different lensed spectra, with particular regard to the B-modes
spectrum, which is almost
entirely
due to the lensing process at intermediate and high multipoles,and is
therefore the best candidate for discriminating among different
Andrés
Balaguera
Antolinez: Equilibrium of
astrophysical structures in expanding universe
The actual acceleration of the universe can be understood
in principle through the inclusion of a positive cosmological constant.
The virialization of large astrophysical structures takes place under
different conditions depending on the cosmological model used. Once a
system is virialized, we can write down the virial conditions for
gravitational equilibrium
not
only in terms of the cosmological constant, but also in terms of the
parameters involved in models that mimic the cosmological constant at
the present time, such as the Chaplygin gas. We show that the angular
velocity of flat astrophysical rotating objects gets affected
considerably in gravitational equilibrium if the universe is
accelerated. We also study the stability criteria under small
perturbations about the equilibrium configuration. The inclusion of a
positive cosmological in this analysis constrains the equation of state
in a stringent way if the astrophysical object under consideration is
not too dense.
Eduardo
Battaner: The
PLANCK mission
PLANCK is mainly designed to
measure CMB, though other astrophysical objectives will be also
covered. The high sensitivity, spectral coverage, spatial resolution
and polarization renders PLANCK a unique opportunity for observational
Cosmology.
María
Beltrán: Cosmological
Parameter determination and
Model Selection
Recent measurements of the
CMB and LSS have made it possible to put stringent bounds on cosmological
parameters. Not much attention has been directed however to the higher-level
inference problem of model selection in cosmology. We use a data set
comprised of WMAP and other CMB data, the 2dF and SDSS power spectra, and Type Ia
supernovae data to constrain isocurvature parameters as well as to
perform model selection using Bayesian
techniques.
Arjun Berera: Warm inflation in
supersymmetric models
Recent, detailed, quantum field theory calculations have shown that
many generic inflation models, including hybrid inflation, which were
believed only to have cold inflation regimes, in fact have regimes of
both warm and cold inflation. These results dispel many foregone
assumptions generally made up to now about inflation models and bring
to the fore various elementary issues that must be addressed to do
reliable calculations from inflation models. In this talk I discuss
these results and issues. I then show that warm inflation has intrinsic
model independent features
that
makes it natural or equivalently have no ``eta problem''. I apply these
results to show warm
inflation
regimes in well known supersymmetric
models.
Mariam
Bouhmadi López: On
Brane-World Induced Gravity
We investigate non-minimal coupling to the Ricci
curvature of a scalar field on a four-dimensional (4D) brane and the
effect this may have on the scalar field dynamics and cosmological
evolution. We deduce the gravitational equations of a 4D brane with an
induced gravity term coupled to a scalar field, in a 5D bulk with a
cosmological constant. On the other hand, we study the gravitational
waves in the setup of brane-world inflation with induced gravity, where
the inflaton is confined on the 4D brane and is minimally coupled to
the Ricci curvature of the 4D brane.
Elie
Chachoua:
Rigidity and Stability of cold dark solid
universe model
This talk describes recent progress on the solid
universe model consisting
of a foam like distribution
of cosmic membranes.
Since
such a model is characterised by a negative pressure to density ratio,
w=-2/3, it has been suggested by Bucher and Spergel that it may account
for the observed cosmological acceleration. However in order to be stable such a system must
have a sufficiently high rigidity. Until recently it was not clear
whether this condition
would be satisfied. The new work presented here provides an exact
numerical evaluation of the rigidity modulus and the confirmation
that it is indeed sufficiently large
for the model to be viable.
Alvaro
Domínguez: Modelling subresolution scales in N-body
simulations
N-body simulations of large-scale structure formation suffer
from the intrinsic problem of a finite resolution. We present a model
of the dynamical influence of subresolution degrees of freedom and the
result of two simulations incorporating them. The morphological and
kinematical properties of the matter distribution are quantified and
compared to those of two standard simulations (cold DM and warm DM). A
preliminary conclusion is that the subresolution corrections favor the
formation of more low-mass clusters and the gain of angular momentum.
Inmaculada
Domínguez: Accuracy
of Type Ia
Supernovae as standard candles
Observational
hints indicate a dependence of the
SN
Ia properties with the populations from which they come from. This may
imply the existence of evolutionary effects, which is the main concern
for a standard candle. Based on our detailed 1D models of
progenitor evolution, explosions and light curves, we have analyzed the
influence of the mass and metallicity of progenitors and of the white
dwarf rotational properties on the SN light curves. Our results do not
question the existence of the dark energy. The obtained differences at
maximum light (0.2 mag) are within the dispersion of the
maximum-decline relation (0.17 mag) used to infer
the luminosity at maximum and, hence, the distances.
However, a precision of 0.05 to 0.1 mag is required to identify
the nature of the dark energy. In this case, rotation and evolutionary
effect should be taken into account to increase the accuracy in the
distance determinations. A complete
understanding of thermonuclear supernovae is fundamental for their use
as
cosmological standard candles. In this context, we revise the current
situation
of the numerical simulations of the various phases.
José Gaite:
Haloes
and
clustering in cosmological simulations: multifractal methods
We study
N-body cosmological simulations to
compare
the halo model of large-scale structure with fractal models. We
show
that both models can be combined in a model consisting of a fractal
distribution
of haloes. Furthermore, we show that the multifractal analysis of
N-body
simulations supports this model.
Enrique
Gaztañaga: Large
scale structure with wide field
galaxy surveys
I will review recent and
future results on large scale structure
using
wide field galaxy
redshift and photometric surveys, such as SDSS, 2dFGRS and the
future DES (Dark Energy Survey). The combination of 2-point and 3-point
correlation functions have been used to study at the same time the nature of
the initial conditions and the subsequent process of gravitational
instability and galaxy formation. The data can be use to estimate dark
matter and dark energy. Current results
are alredy precise enough to constraint some of the degeneracies in the models, such as the
value of sigma8, the rms linear normalizacion for the amplitude dark matter
fluctuations, and the bias parameter "b". Cross-correlation of these
galaxy catalogues with WMAP (and future wide field CMB maps, such as
Planck) also brings new light in the dark cosmos
Shahram
Jalalzadeh: On
extra forces from large extra dimensions
The motion of a classical
test particle moving on a
4-dimensional brane embedded in an $n$-dimensional bulk is studied in
which the brane is allowed to fluctuate along the extra dimensions. It
is shown that these fluctuations produce three different forces acting
on the particle, all stemming from the effects of extra dimensions.
Interpretations are offered to describe the origin of these forces and
a relationship between the 4 and $n$-dimensional mass of the particle
is obtained by introducing charges associated with large extra
dimensions.
José
A. Jiménez Madrid: Scaping the Big
Rip?
We discuss dark
energy models which might describe
effectively
the actual acceleration of the universe. More precisely, for a
4-dimensional
Friedmann-Lema\^{\i}tre-Robertson-Walker (FLRW) universe we consider
two
situations: First of them, we model dark energy by phantom energy
described
by a perfect fluid satisfying the equation of state $P=(\beta-1)\rho$
(with
$\beta<0$ and constant). In this case the universe reaches a ``Big
Rip''
independently of the spatial geometry of the FLRW universe. In the
second
situation, the dark energy is described by a phantom (generalized)
Chaplygin
gas which violates the dominant energy condition. Contrary to the
previous
case, for this material content a FLRW universe would never reach a
``big
rip'' singularity (indeed, the geometry is asymptotically de Sitter).
We
also show how this dark energy model can be described in terms of
scalar
fields, corresponding to a minimally coupled scalar field, a
Born-Infeld
scalar field and a generalized Born-Infeld scalar field.
Valeria
Kagramanova: Particles motion in
the vicinity of slowly
rotating star with nonzero gravitomagnetic charge
Investigation
of some general relativistic properties of the spacetime structure
outside
central axial-symmetric slowly rotating massive body with nonzero
gravitomagnetic
charge has been presented. A mass M endowed with a gravitomagnetic
monopole
with strength l (NUT parameter or magnetic mass) was considered. The
gravitomagnetic
effects on a test particle nonrelativistically moving along an
equatorial
circular geodesic orbit in a plane containing the proper angular
momentum
a of the central source of gravitomagnetic origin was elucidated. Driven by the gravitomagnetic
analogues
it was asked whether the NUT parameter could act on the moving test
particles
in the vicinity of the massive body. For this purpose the equations of
motion
and the effective potential for particles motion were investigated. It
was
shown the qualitative difference in the motion of the particles in the
presence
of NUT parameter with compare to the motion of the particles in the
Kerr
metric (when l=0). The effect of NUT parameter on the trajectories of
the
test particles may play an important role near the surface of the
compact
object.
Julien
Lesgourgues: A short review on
inflation: theory and constraints
I will
present a very broad introduction to the
theory
of inflation, and review the current constrains derived from CMB
anisotropies
and large scale stucture.
David
Lyth: Non-gaussianity
made easy
I explain how the Sasaki-Stewart delta N formula may be used to
calculate
the curvature
perturbation to any order of perturbation theory, using only
the properties of a family of
unperturbed universes. The only assumption
is that the evolution of this
family is determined by the values, soon
after horizon exit, of some
light fields with gaussian perturbations.
Non-gaussianity generated
subsequently is fully described, and is free of
inverse Laplacians, ie. is
purely local. The case of un-correlated
non-gaussianity is described
for the first time.
Marc
Manera: Constraining
cosmological parameters by CMB-galaxy cross-correlations thomography
Recent studies by a number of independent collaborations find a
systematically positive cross-correlation between the CMB temperatures
mesured by WMAP satellite and diferent galaxy surveys
that trace the matter
distribution. Combining data with diferent redshifts allow us to
constrain cosmological parametres, thus
finding new evidence for dark
energy content. For a flat universe
with fixed matter content one can also start constraining the
equation of state. (see astroph/0407022)
Irit
Maor: On virialization with dark energy
A primary question in today's cosmology is whether dark
energy is a cosmological constant, or is it dynamical. In order to use
inhomogeneity studies to probe dark energy, it is essential that we
understand how the presence of dark energy affects the evolution of
overdensities.
The
spherical collapse formalism is a simple model which describes how the
initial overdensities in the matter evolve into bound structures. I
will review the inclusion of an additional energy source (different
than matter) to the formalism of spherical collapse.
Germán
Olivares: Observational constraints on interacting
quintessence models
We determine the range of parameter space of Interacting Quintessence
Models
that best fits the recent
WMAP measurements of Cosmic Microwave Background
temperature anisotropies. We
only consider cosmological models with zero
spatial curvature. We show
that if the quintessence scalar field decays
into cold dark matter at a
rate that brings the ratio of matter to dark
energy constant at late
times,the cosmological parameters required to fit
the CMB data
are: \Omega_x = 0.43 \pm
0.12, baryon fraction \Omega_b = 0.08 \pm 0.01,
slope of the matter power
spectrum at large scals n_s = 0.98 \pm 0.02 and
Hubble constant H_0 = 56 \pm
4 km/s/Mpc. The data prefers a dark energy component with
a dimensionless decay
parameter c^2 =0.005 and non-interacting models are
consistent with the data only
at the 99% confidence level. Using the
Bayesian Information Criteria
we show that this exra parameter fits the
data better than
models with no interaction.
The quintessence equation of state parameter
is less constrained; i.e.,
the data set an upper limit w_x \leq -0.86 at
the same level of
significance. When the WMAP anisotropy data are combined
with supernovae data, the
density parameter of dark energy increases to
\Omega_x \simeq 0.68 while
c^2 augments to 6.3 \times 10^{-3}. Models with
quintessence decaying into
dark matter provide a clean explanation for the
coincidence problem and are a
viable cosmological model, compatible with
observations of the CMB, with
testable predictions. Accurate measurements
of baryon fraction and/or of
matter density independent of the CMB data,
would support/disprove these
models.
Diego
Nicola Pelliccia: Scalar field instability in de Sitter
space-time
Starting from the equation of motion of the quantum operator of a real
scalar field in de Sitter space-time, a simple differential equation is
derived which describes the evolution of quantum fluctuations of this
field. Full de Sitter invariance is assumed and no ad hoc infrared
cutoff is introduced. This equation is solved explicitly and in massive
case the result agrees with the standard one. In massless case the
large time behavior of the solution differs by sign from the expression
found in the literature. Possible causes of discrepancy may be
spontaneous breaking of de Sitter invariance or quantum anomalies.
Vicent
Quilis: The Universe within a Supercomputer
This talk will be focused on the field of Numerical Cosmology,
and how the
numerical
simulations have help us to understand the formation and
evolution of the structures
in the Universe. I will start by reviewing the basic theoretical
concepts and numerical techniques used in
cosmological simulations.
Then, I will describe some of the most
important results from the
simulations and their influence on the actual
cosmological paradigm.
Regardless of the undoubtable success of the
previous generation of
cosmological simulations, recent observations have
shown severe problems in the
model. I will describe the new generation
of simulations and some of
promising ideas, which coupled, are expected
to solve the still open
problems.
Erandy
Ramírez: Stochastic approaches to inflation model
building
Typically models of inflation are motivated either by fundamental
physics considerations or by
simplicity. An alternative is to generate
large numbers of models via a
random generation process such as
the flow equations approach. We consider a different
implementation of the
flow
equations using an analytic solution found previously, and then
consider alternative
stochastic methods of generating large number of
inflation models with the aim
of testing whether the
structures
generated by the flow equations are robust. We find that there
remains some concentration of
points in the observable plane under the
different methods but there
is significant variation in the
predictions
amongst the methods considered.
Yeinzon
Rodríguez García: Non-gaussianity from the second-order
perturbation
Several conserved and/or gauge invariant
quantities
described as the second-order curvature perturbation have been given in
the literature. We review each of these quantities showing how to
interpret
one in terms of the others and analyzing the respective expected level
of
primordial non-gaussianity in single models of inflation of the
slow-roll
variety. The importance of the knowledge of the initial conditions is
highlighted
but, nevertheless, some useful information about the time evolution of
the
second-order curvature perturbation may be obtained without them.
Pilar
Ruíz-Lapuente: Dark
energy
and supernovae
This is an overview of the
progress in the determination of the nature of dark energy from
supernovae. Current surveys and methods of analysis are reviewed.
Future prospects will be discussed.
Antonio
Seguí: Causal
structure and observables in
cosmology
We analyze the causal structure for different cosmological models. It
allows us to study the properties of the observables that in an
operative way admit an asymptotic description. We find restrictions to
the observables when we take into account the entropic limits as well
as the thermal properties of the studied models. We cojecture on the
nature of the restrictions in the context of quantum gravity.
Osamu
Seto: Solving gravitino problem by a brane world
effect
We investigate the thermal production of gravitinos in brane world
cosmology. Since the expansion law is modified from that in the
standard cosmology, the Boltzmann equation for the gravitino production
is also changed. We find that the late-time gravitino abundance is
proportional to the ``transition temperature'', at which the modified
expansion law in the brane world cosmology is connecting with the
standard one, rather than the reheating temperature after inflation as
in the standard cosmology. This means that, even though the reheating
temperature is very high, we can avoid the overproduction of gravitinos
by taking the transition temperature low enough.
By
using
high resolution quasar spectra I will recover the linear dark matter
power
spectrum at scales of 1-40 comoving Mpc. These scales cannot probed by
any
other observable. When combined with Cosmic Microwave Background data
we
get tight constraints on: cosmological parameters (sigma_8, scalar
spectral
index and its running), slow-roll inflationary models, mass of a warm
dark
matter particle (such as sterile neutrinos or light gravitinos).
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