What can the spatial distribution of galaxy clusters tell about their scaling relations?

We aim to quantify the capability of the inhomogeneous distribution of galaxy clusters, represented by the two-point statistics in Fourier space, to retrieve information on the underlying scaling relations. We make a case study using the mass X-ray luminosity scaling relation for galaxy clusters and study its impact on the clustering pattern of these objects. We define the luminosity-weighted power spectrum and introduce the luminosity power spectrum as direct assessment of the clustering of the property of interest, in our case, the cluster X-ray luminosity. Using a suite of halo catalogs extracted from N-body simulations and realistic estimates of the mass X-ray luminosity relation, we measured these statistics with their corresponding covariance matrices. By carrying out a Fisher matrix analysis, we quantified the content of information (by means of a figure-of merit) encoded in the amplitude, shape, and full shape of our probes for two-point statistics. The full shape of the luminosity power spectrum, when analyzed up to scales of k~0.2 h/Mpc, yields a figure of merit which is two orders of magnitude above the figure obtained from the unweighted power spectrum, and only one order of magnitude below the value encoded in X-ray luminosity function estimated from the same sample. This is a significant improvement over the analysis developed with the standard (i.e., unweighted) clustering probes. The measurements of the clustering of galaxy clusters and its explicit dependence on the cluster intrinsic properties can contribute to improving the degree of knowledge regarding the underlying links between cluster observables and the cluster masses (Abridged).Comment: 12 pages, 9 figures. Accepted for publication in Astronomy and Astrophysic

The cosmic web connection to the dark matter halo distribution through gravity

In this letter we investigate the connection between the cosmic web and the halo distribution through the gravitational potential. We combine three fields of research, cosmic web classification, perturbation theory expansions of the halo bias, and halo (galaxy) mock catalog making methods. In particular, we use the invariants of the tidal field tensor as generating functions (dubbed I-web), to reproduce the halo number counts of a reference catalog from full gravity calculations, populating the dark matter field on a mesh well into the non-linear regime ($\sim5$ Mpc scales). Our results show an unprecedented agreement with the reference power spectrum within 0.5% up to $k=0.72\,h$ Mpc$^{-1}$. By analysing the three point statistics on large scales (configurations of up to $k=0.2\,h$ Mpc$^{-1}$), we find evidence for non-local bias at the 4.8 $\sigma$ confidence level (an information gain of $\sim$ 3.4 $\sigma$ over the commonly used T-web), being fully compatible with the reference catalog. In particular, we find that a detailed description of tidal anisotropic clustering on large scales is crucial to achieve this accuracy. We conclude that the I-web can potentially be useful to study the cosmic web, to improve the generation of mock galaxy catalogs, to improve on halo mass reconstructions, to study primordial non-Gaussianities, to develop new effective Eulerian galaxy bias models at the field level, and to investigate galaxy evolution improving on environmental studies.Comment: 5 pages, 3. figures and supplemental material with 11 page, 4 figuresand 2 table

DESI Mock Challenge: Halo and galaxy catalogs with the bias assignment method

We present a novel approach to the construction of mock galaxy catalogues for large-scale structure analysis based on the distribution of dark matter halos obtained with effective bias models at the field level. We aim to produce mock galaxy catalogues capable of generating accurate covariance matrices for a number of cosmological probes that are expected to be measured in current and forthcoming galaxy redshift surveys (e.g. two- and three-point statistics). We use the bias assignment method (BAM) to model the statistics of halo distribution through a learning algorithm using a few detailed $N$-body simulations, and approximated gravity solvers based on Lagrangian perturbation theory. Using specific models of halo occupation distributions, we generate galaxy mocks with the expected number density and central-satellite fraction of emission-line galaxies, which are a key target of the DESI experiment. BAM generates mock catalogues with per cent accuracy in a number of summary statistics, such as the abundance, the two- and three-point statistics of halo distributions, both in real and redshift space. In particular, the mock galaxy catalogues display $\sim 3\%-10\%$ accuracy in the multipoles of the power spectrum up to scales of $k\sim 0.4\,h^{-1}{\rm Mpc}$. We show that covariance matrices of two- and three-point statistics obtained with BAM display a similar structure to the reference simulation. BAM offers an efficient way to produce mock halo catalogues with accurate two- and three-point statistics, and is able to generate a variety of multi-tracer catalogues with precise covariance matrices of several cosmological probes. We discuss future developments of the algorithm towards mock production in DESI and other galaxy-redshift surveys. (Abridged)Comment: Accepted for publication at A&

Options. Journal of the UNAB Financial Engineering Program. Volume 4 No. 7 June 2010

Las opiniones contenidas en los artículos de esta revista no vinculan a la institución sino que son de exclusiva responsabilidad de los autores, dentro de los principios democráticos de cátedra libre y libertad de expresión, consagrados en el artículo 3° del Estatuto General de la Corporación Autónoma de Bucaramanga. El material de esta publicación puede ser reproducido sín autorización, siempre y cuando se mencione su procedencia y el Programa de Ingeniería Financiera de la UNAB reciba un ejemplar de su publicación.Editorial. - 5 Los mercados de energía eléctrica en América Latina y Europa. - 7 Perfil del emprendedor en Bucaramanga. - 19 CRM o el camino a la calidad del servicio. - 30 Importancia del XBRL. - 37 Diseño y evaluación financiera de la creación de un centro de maquinaria agrícola para los cultivadores de tabaco del Huila y su impacto en la estructura de costos del cultivo. 41 Importancia de la intervención del estado colombiano en el sistema financiero. - 50 Análisis y valoración del riesgo de precio de energía eléctrica en Colombia. - 55The opinions contained in the articles of this magazine do not bind the institution but are exclusive responsibility of the authors, within the democratic principles of free teaching and freedom of expression, enshrined in article 3 of the General Statute of the Autonomous Corporation of Bucaramanga. The material in this publication may be reproduced without authorization, as long as its origin and the Financial Engineering Program of UNAB receives a copy of your publication

Cosmological and astrophysical structures in the Einstein-de Sitter space time

In this work we explore the consequences of a non zero cosmological constant on cosmological and astrophysical structures. We find that the effects are associated to the density of the configurations as well as to the geometry. Homogeneous and spherical configurations are slightly affected. For non homogeneous configurations, we calculate the effects on a polytropic configurations and on the isothermal sphere, making special emphasis on the fact that the cosmological constant sets certain scales of length, time, mass and density. Sizable effects are determined for non spherical systems, as elliptical galaxies or galactic clusters, where the effects of A are increased as long as the configurations deviates from spherical symmetry, i.e, for flat systems. The equilibrium of rotating ellipsoids are modified and the cosmological constant allows new configurations in equilibrium. Finally we explore the motion of a test particle in the Schwarszchild- de Sitter space time and set astrophysical bounds for the cosmological constant, not only from the Newtonian limit, but also from a full general relativistic analysis.Magíster en FísicaMaestrí

One simulation to have them all: Performance of the Bias Assignment Method against N-body simulations

In this paper, we demonstrate that the information encoded in one single (sufficiently large) N-body simulation can be used to reproduce arbitrary numbers of halo catalogues, using approximated realizations of dark matter density fields with different initial conditions. To this end, we use as a reference one realization (from an ensemble of 300) of the Minerva N-body simulations and the recently published Bias Assignment Method to extract the local and non-local bias linking the halo to the dark matter distribution. We use an approximate (and fast) gravity solver to generate 300 dark matter density fields from the down-sampled initial conditions of the reference simulation and sample each of these fields using the halo-bias and a kernel, both calibrated from the arbitrarily chosen realization of the reference simulation. We show that the power spectrum, its variance, and the three-point statistics are reproduced within ∼2 per cent (up to k ∼ 1.0hMpc), ∼5 - 10 per cent, and ∼ 10 per cent, respectively. Using a model for the real space power spectrum (with three free bias parameters), we show that the covariance matrices obtained from our procedure lead to parameter uncertainties that are compatible within ∼ 10 per cent with respect to those derived from the reference covariance matrix, and motivate approaches that can help to reduce these differences to ∼ 1 per cent. Our method has the potential to learn from one simulation with moderate volumes and high-mass resolution and extrapolate the information of the bias and the kernel to larger volumes, making it ideal for the construction of mock catalogues for present and forthcoming observational campaigns such as Euclid or DESI.ABA acknowledges financial support from the Spanish Ministry of Economy and Competitiveness (MINECO) under the Severo Ochoa program SEV-2015-0548. FSK thanks support from grants SEV-2015-0548, RYC2015-18693, and AYA2017-89891-P. MPI acknowledges support from MINECO under the grant AYA2012-39702-C02-01. MPI wishes to acknowledge the contribution of Teide High-Performance Computing facilities for the results of this research. TeideHPC facilities are provided by the Instituto Tecnol?gico y de Energ?as Renovables (ITER, SA). REA and MPI acknowledge the Spanish MINECO and the European Research Council through grants AYA2015-66211-C2-2 and ERC-StG/716151, respectively