149 research outputs found
The Cosmic Web from Perturbation Theory
Context: Analyzing the large-scale structure (LSS) with galaxy surveys
demands accurate structure formation models. Such models should ideally be fast
and have a clear theoretical framework to rapidly scan a variety of
cosmological parameter spaces without requiring large training data sets. Aims:
This study aims to extend Lagrangian perturbation theory (LPT), including
viscosity and vorticity, to reproduce the cosmic evolution from dark matter
N-body calculations at the field level. Methods: We extend LPT to an Eulerian
framework, dubbed eALPT. An ultraviolet regularisation through the spherical
collapse model provided by Augmented LPT, turns out to be crucial at low
redshifts. This enables modelling the stress tensor, with this introducing
vorticity. The model has two free parameters apart from the choice of
cosmology, redshift snapshots, cosmic volume, and the number of
particles-cells. Results: We find that the cross-correlation of the dark matter
distribution as compared to N-body solvers increases at Mpc
and from 55\% with the Zel'dovich approximation (70\% with
ALPT), to 95\% with three timesteps eALPT, and power spectra within
percentage accuracy up to Mpc.Comment: 6 pages, 3 figure
All-sky angular power spectra from cleaned WISESuperCOSMOS galaxy number counts
Aiming to extract cosmological information from linear scales of the
WISESuperCOSMOS photometric redshift catalog, we perform a
characterization of the systematic effects associated with stellar content,
evidencing the presence of contamination and obscuration. We create an
integrated model for these effects (which together we call `usurper
contamination'), devise a method to remove both of them simultaneously and show
its functionality by applying it to a set of mock catalogs. When administered
to WISESuperCOSMOS data, our method shows to improve the measurements
of angular power spectra on scales and the extraction of
cosmological parameters therefrom, even though a significant excess of power
remains at these scales. When ignoring scales , we still find strong
indications of systematics, albeit these can be localized in the southern
equatorial hemisphere. An independent analysis of the northern hemisphere at
agrees with a CDM model with parameters from the Planck
satellite and gives and
at 95% confidence limit when combined with priors
on , and .Comment: 33 pages, 20 figures, 5 tables. Accepted for publication in JCA
Sistema multiobjetivo de soporte a decisiones para planificación de programación de operaciones
This research shows the design and construction of a multi objective optimization support system for decision making, DSS-SCHEDULER, in order to effectively perform naval shipbuilding operations, by managing to have a rational usage, under a limited capacity, of the installed capacity. The system creates the operational plan for the scheduling of operations as well as the allocation of all the resources related to the processes carried out at the plant, and, taking into account all the restrictions this type of service entails, generate a set of optimal solutions in order to comply with the objective functions as planned, such as costs and the promise for delivery dates to support the decision making process in scheduling Cotecmar’s industrial operations.La presente investigación muestra el diseño y construcción de un sistema de optimización Multiobjetivo de soporte a toma de decisiones, DSS-SCHEDULER, para realizar de manera efectiva la actividad de programación de operaciones en planta de astilleros navales, logrando una utilización racional, bajo capacidad finita, de la capacidad instalada, el cual realiza la creación de la planificación operativa de programación de operaciones y la asignación de todos los recursos asociados a los procesos que se realizan en la planta, y teniendo en cuenta todas las restricciones que conlleva estos servicios, generar un conjunto de soluciones óptimas cumpliendo con las funciones objetivo propuestas, como costos y promesa de fechas de entrega para apoyar la toma de decisiones de la programación de las operaciones industriales de Cotecmar
Report of the Age Calibration Exercise Analysis for Anchovy in Division 9a (IBERAS survey 2018)
In November 2018, a new acoustic survey (IBERAS) coordinated by IEO and IPMA was
carried out in order to estimate the strength of sardine and anchovy recruitment in the Atlantic
waters of the Iberian Peninsula (ICES Division 9a) and to map its distribution area. As well as
determine the main biological characteristics of these species in the area.
In January-February 2019, an otolith reading exercise was carried out on the anchovy from the
survey to determine its age, with the objective of calibrating the age readings among the
anchovy readers of the IEO and the IPMA, and estimating the accuracy and discrepancies in the
determination of anchovy age among these readers. As well as, to obtain the age length keys of
the surve
Minimum mass-radius ratio for charged gravitational objects
We rigorously prove that for compact charged general relativistic objects
there is a lower bound for the mass-radius ratio. This result follows from the
same Buchdahl type inequality for charged objects, which has been extensively
used for the proof of the existence of an upper bound for the mass-radius
ratio. The effect of the vacuum energy (a cosmological constant) on the minimum
mass is also taken into account. Several bounds on the total charge, mass and
the vacuum energy for compact charged objects are obtained from the study of
the Ricci scalar invariants. The total energy (including the gravitational one)
and the stability of the objects with minimum mass-radius ratio is also
considered, leading to a representation of the mass and radius of the charged
objects with minimum mass-radius ratio in terms of the charge and vacuum energy
only.Comment: 19 pages, accepted by GRG, references corrected and adde
Ellipsoidal configurations in the de Sitter spacetime
The cosmological constant modifies certain properties of large
astrophysical rotating configurations with ellipsoidal geometries, provided the
objects are not too compact. Assuming an equilibrium configuration and so using
the tensor virial equation with we explore several equilibrium
properties of homogeneous rotating ellipsoids. One shows that the bifurcation
point, which in the oblate case distinguishes the Maclaurin ellipsoid from the
Jacobi ellipsoid, is sensitive to the cosmological constant. Adding to that,
the cosmological constant allows triaxial configurations of equilibrium
rotating the minor axis as solutions of the virial equations. The significance
of the result lies in the fact that minor axis rotation is indeed found in
nature. Being impossible for the oblate case, it is permissible for prolate
geometries, with zero and positive. For the triaxial case, however,
an equilibrium solution is found only for non-zero positive . Finally,
we solve the tensor virial equation for the angular velocity and display
special effects of the cosmological constant there.Comment: 15 pages, 11 figures, published in Class. Quant. Grav. References
adde
Probing dark energy with the next generation X-ray surveys of galaxy clusters
We present forecasts on the capability of future wide-area high-sensitivity
X-ray surveys of galaxy clusters to yield constraints on the parameters
defining the Dark Energy (DE) equation of state (EoS). Our analysis is carried
out for future X-ray surveys which have enough sensitivity to provide accurate
measurements of X-ray mass proxies and Fe-line based redshifts for about 2x10^4
clusters. We base our analysis on the Fisher Matrix formalism, by combining
information on the cluster number counts and power spectrum, also including,
for the first time in the analysis of the large scale cluster distribution, the
effect of linear redshift-space distortions (RSDs). This study is performed
with the main purpose of dissecting the cosmological information provided by
geometrical and growth tests, which are both included in the analysis of number
counts and clustering of galaxy clusters. We compare cosmological constraints
obtained by assuming different levels of prior knowledge of the parameters
which define the observable-mass X-ray relation. This comparison further
demonstrates the fundamental importance of having a well calibrated
observable-mass relation and, most importantly, its redshift evolution. Such a
calibration can be achieved only by having at least net photon
counts for each cluster included in the survey. We show that RSDs in the power
spectrum analysis carry important cosmological information also when traced
with galaxy clusters and the DE FoM increases by a factor of 8. Besides
confirming the potential that large cluster surveys have in constraining the
nature of DE, our analysis emphasizes that a full exploitation of the
cosmological information carried by such surveys requires not only a large
statistic but also a robust measurement of the mass proxies and redshifts for a
significant fraction of the cluster sample, derived from the same X-ray survey
data.Comment: 16 pages, 14 figures,published on MNRA
Euclid preparation: VII. Forecast validation for Euclid cosmological probes
Aims: The Euclid space telescope will measure the shapes and redshifts of galaxies to reconstruct the expansion history of the Universe and the growth of cosmic structures. The estimation of the expected performance of the experiment, in terms of predicted constraints on cosmological parameters, has so far relied on various individual methodologies and numerical implementations, which were developed for different observational probes and for the combination thereof. In this paper we present validated forecasts, which combine both theoretical and observational ingredients for different cosmological probes. This work is presented to provide the community with reliable numerical codes and methods for Euclid cosmological forecasts.
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Methods: We describe in detail the methods adopted for Fisher matrix forecasts, which were applied to galaxy clustering, weak lensing, and the combination thereof. We estimated the required accuracy for Euclid forecasts and outline a methodology for their development. We then compare and improve different numerical implementations, reaching uncertainties on the errors of cosmological parameters that are less than the required precision in all cases. Furthermore, we provide details on the validated implementations, some of which are made publicly available, in different programming languages, together with a reference training-set of input and output matrices for a set of specific models. These can be used by the reader to validate their own implementations if required.
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Results: We present new cosmological forecasts for Euclid. We find that results depend on the specific cosmological model and remaining freedom in each setting, for example flat or non-flat spatial cosmologies, or different cuts at non-linear scales. The numerical implementations are now reliable for these settings. We present the results for an optimistic and a pessimistic choice for these types of settings. We demonstrate that the impact of cross-correlations is particularly relevant for models beyond a cosmological constant and may allow us to increase the dark energy figure of merit by at least a factor of three
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