Improving the precision matrix for precision cosmology

The estimation of cosmological constraints from observations of the large scale structure of the Universe, such as the power spectrum or the correlation function, requires the knowledge of the inverse of the associated covariance matrix, namely the precision matrix, $\mathbf{\Psi}$. In most analyses, $\mathbf{\Psi}$ is estimated from a limited set of mock catalogues. Depending on how many mocks are used, this estimation has an associated error which must be propagated into the final cosmological constraints. For future surveys such as Euclid and DESI, the control of this additional uncertainty requires a prohibitively large number of mock catalogues. In this work we test a novel technique for the estimation of the precision matrix, the covariance tapering method, in the context of baryon acoustic oscillation measurements. Even though this technique was originally devised as a way to speed up maximum likelihood estimations, our results show that it also reduces the impact of noisy precision matrix estimates on the derived confidence intervals, without introducing biases on the target parameters. The application of this technique can help future surveys to reach their true constraining power using a significantly smaller number of mock catalogues.Comment: 9 pages, 7 figures, minor changes to match version accepted by MNRA

Anisotropic halo model

In the present work, we extend the classic halo model for the large-scale matter distribution including a triaxial model for the halo profiles and their alignments. In particular, we derive general expressions for the halo-matter cross correlation function. In addition, by numerical integration, we obtain instances of the cross-correlation function depending on the directions given by halo shape axes. These functions are called anisotropic cross-correlations. With the aim of comparing our theoretical results with the simulations, we compute averaged anisotropic correlations in cones with their symmetry axis along each shape direction of the centre halo. From these comparisons we characterise and quantify the alignment of dark matter haloes on the ΛCDM context by means of the presented anisotropic halo model. As our model requires multidimensional integral computation we implement a Monte Carlo method on GPU hardware which allows us to increase the precision of the results whereas it improves the performance of the computation.publishedVersio

Void Dynamics

Cosmic voids are becoming key players in testing the physics of our Universe. Here we concentrate on the abundances and the dynamics of voids as these are among the best candidates to provide information on cosmological parameters. Cai, Padilla \& Li (2014) use the abundance of voids to tell apart Hu \& Sawicki $f(R)$ models from General Relativity. An interesting result is that even though, as expected, voids in the dark matter field are emptier in $f(R)$ gravity due to the fifth force expelling away from the void centres, this result is reversed when haloes are used to find voids. The abundance of voids in this case becomes even lower in $f(R)$ compared to GR for large voids. Still, the differences are significant and this provides a way to tell apart these models. The velocity field differences between $f(R)$ and GR, on the other hand, are the same for halo voids and for dark matter voids. Paz et al. (2013), concentrate on the velocity profiles around voids. First they show the necessity of four parameters to describe the density profiles around voids given two distinct void populations, voids-in-voids and voids-in-clouds. This profile is used to predict peculiar velocities around voids, and the combination of the latter with void density profiles allows the construction of model void-galaxy cross-correlation functions with redshift space distortions. When these models are tuned to fit the measured correlation functions for voids and galaxies in the Sloan Digital Sky Survey, small voids are found to be of the void-in-cloud type, whereas larger ones are consistent with being void-in-void. This is a novel result that is obtained directly from redshift space data around voids. These profiles can be used to remove systematics on void-galaxy Alcock-Pacinsky tests coming from redshift-space distortions.Comment: 8 pages, 4 figures, to appear in the proceedings of IAU308 Symposium "The Zeldovich Universe

Halos de materia y estructura en gran escala /

Tesis (Doctor en Astronomía)--Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física, 2010.Las galaxias, grupos y cúmulos, representan los mayores sistemas ligados de materia, y por ello proveen información invaluable sobre el surgimiento, formación y evolución de estructuras en el universo. Es también frecuente referirse a estos sistemas como halos de materia, o simplemente halos. En esta tesis se analiza la dinámica de estos objetos, en un amplio rango de masas y escalas. Como es sabido, la estructura en gran escala del universo puede ser descripta, en primera aproximación, como un campo gaussiano en densidad completamente caracterizado por su espectro de potencias. Dicho espectro se aproxima a una ley de potencias, en un amplio rango de escalas. Los campos en densidad que siguen esta ley presentan ciertas características fractales, tales como la autosimilitud de estructuras a diferentes escalas. Luego podemos esperar, si bien no autosimilitud estricta, cierto grado de uniformidad en la fenomenología y teoría de los halos de materia, en un amplio rango de escalas y masas. Por lo cual es posible incluir objetos astronómicos de diferentes tamaños y masas, como galaxias, grupos de galaxias y grandes cúmulos, en un análisis cualitativo unificado.Fil: Paz, Dante Javier. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina

Deviations from tidal torque theory: Environment dependences on halo angular momentum growth

The tidal torque theory (TTT) relates the origin and evolution of angular momentum with the environment in which dark matter (DM) haloes form. The deviations introduced by late non-linearities are commonly thought as noise in the model. In this work, we analyse a cosmological simulation looking for systematics on these deviations, finding that the classification of DM haloes according to their angular momentum growth results in samples with different internal alignment, spin parameter distribution, and assembly history. Based on this classification, we obtain that low-mass haloes are embedded in denser environments if they have acquired angular momentum below the TTT expectations (L haloes), whereas at high masses enhanced clustering is typically associated with higher angular momentum growths (W haloes). Additionally, we find that the low-mass signal has a weak dependence on the direction, whereas the high-mass signal is entirely due to the structure perpendicular to the angular momentum. Finally, we study the anisotropy of the matter distribution around haloes as a function of their mass. We find that the angular momentum direction of W (L) haloes remains statistically perpendicular (parallel) to the surrounding structure across the mass range 11 < log(M/h-1M⊙) < 14, whereas haloes following TTT show a 'spin flip' mass consistent with previously reported values (∼5 × 1012 h-1M⊙). Hence, whether the spin flip mass of the deviated samples is highly shifted or straightly undefined, our results indicate that it is remarkably connected to the haloes angular momentum growth.Fil: López, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Merchan, Manuel Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Paz, Dante Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; Argentin

Clues on void evolution II: Measuring density and velocity profiles on SDSS galaxy redshift space distortions

Using the redshift-space distortions of void-galaxy cross-correlation function we analyse the dynamics of voids embedded in different environments. We compute the void-galaxy crosscorrelation function in the Sloan Digital Sky Survey (SDSS) in terms of distances taken along the line of sight and projected into the sky. We analyse the distortions on the cross-correlation isodensity levels and we find anisotropic isocontours consistent with expansion for large voids with smoothly rising density profiles and collapse for small voids with overdense shells surrounding them. Based on the linear approach of gravitational collapse theory we developed a parametric model of the void-galaxy redshift space cross-correlation function. We show that this model can be used to successfully recover the underlying velocity and density profiles of voids from redshift space samples. By applying this technique to real data, we confirm the twofold nature of void dynamics: large voids typically are in an expansion phase whereas small voids tend to be surrounded by overdense and collapsing regions. These results are obtained from the SDSS spectroscopic galaxy catalogue and also from semi-analytic mock galaxy catalogues, thus supporting the viability of the standard ΛCDM model to reproduce large scale structure and dynamics.Fil: Paz, Dante Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomia Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomia Teórica y Experimental; ArgentinaFil: Lares Harbin Latorre, Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomia Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomia Teórica y Experimental; ArgentinaFil: Ceccarelli, Maria Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomia Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomia Teórica y Experimental; ArgentinaFil: Padilla, Nelson David. Pontificia Universidad Católica de Chile; Chile. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Garcia Lambas, Diego Rodolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomia Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomia Teórica y Experimental; Argentin

Clues on void evolution – I. Large-scale galaxy distributions around voids

We perform a statistical study focused on void environments. We examine galaxy density profiles around voids in the Sloan Digital Sky Survey (SDSS), finding a correlation between void-centric distance to the shell of maximum density and void radius when a maximum in overdensity exists. We analyse voids with and without a surrounding overdense shell in the SDSS. We find that small voids are more frequently surrounded by overdense shells whereas the radial galaxy density profile of large voids tends to rise smoothly towards the mean galaxy density. We analyse the fraction of voids surrounded by overdense shells finding a continuous trend with void radius. The differences between voids with and without an overdense shell around them can be understood in terms of whether the voids are, on average, in the process of collapsing or continuing their expansion, respectively, in agreement with previous theoretical expectations. We use numerical simulations coupled to semi-analytic models of galaxy formation in order to test and interpret our results. The very good agreement between the mock catalogue results and the observations provides additional support to the viability of a Λ cold dark matter model to reproduce the large-scale structure of the Universe as defined by the void network, in a way which has not been analysed previously.Fil: Ceccarelli, Maria Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomia Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomia Teórica y Experimental; ArgentinaFil: Paz, Dante Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomia Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomia Teórica y Experimental; ArgentinaFil: Lares Harbin Latorre, Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomia Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomia Teórica y Experimental; ArgentinaFil: Padilla, Nelson David. Pontificia Universidad Católica de Chile; Chile. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Garcia Lambas, Diego Rodolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomia Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomia Teórica y Experimental; Argentin

Metformin prevents the increase of nitric oxide and lipid peroxidation induced by dehydroepiandrosterone in early pregnant mice

The aim of this work was to study the effects of dehydroepiandrosterone (DHEA) and metformin (M) on nitric oxide (NO) system and oxidative stress in embryo implantation sites of early pregnant mice. The biguanide M is used for treating polycystic ovary syndrome but its complete mechanism of action remains unknown. Nitric oxide (NO) has important protective roles during pregnancy, keeping uterine relaxation and vascular function. However, its overproduction leads to nitrative stress by producing reactive nitrogen species. Here we measured NO content by Griess method and the localization of inducible and endothelial nitric oxide synthase (iNOS and eNOS) by immunohistochemistry in implantation sites. Also we measured lipid peroxidation by TBA-RS, glutathion by Ellman’s reaction and antioxidant enzymes by enzymatic kinetics in uterine homogenates. We found that the expression of both iNOS and eNOS and the NO content were increased with DHEA (p<0.001 for all) and restored to control levels with DHEA+M. Oxidative stress: DHEA increased lipid peroxidation (p<0.01) and glutathione (GSH, p<0.01). With DHEA+M lipid peroxidation was restored to control levels. The activities of the antioxidant enzymes superoxide dismutase and catalase were not modified. We conclude that hyperandrogenization with DHEA enhances the NO system and lipid peroxidation in implantation sites of early pregnant mice and that M treatment prevents these effects.Fil: Luchetti, Carolina Griselda. Universidad de Buenos Aires. Facultad de Agronomía. Pabellón de Zootecnica. Laboratorio de Biotecnología Animal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Paz, Dante Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Motta, Alicia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos. Universidad de Buenos Aires. Facultad de Medicina. Centro de Estudios Farmacológicos y Botánicos; Argentin

El rol y el alcance de la medición en la simulación astronómica

El concepto de medición se halla sujeto a una cierta tensión originada por estos dos ámbitos dentro de la práctica científica. El objetivo del presente trabajo consiste en mostrar el alcance que poseen las mediciones logradas- a partir de las simulaciones computacionales con respecto a aquellas obtemdas medIante la observación tradicional

Implementación del TPM para mejorar la gestión en el área de planeamiento en la empresa JC Electrohidráulicos S. A. C. en el año 2021

El presente trabajo de implementación del TPM, tiene como objetivo principal mejorar la gestión del área de planeamiento de la empresa JC Electrohidráulicos S.A.C. quien brinda servicio integrado de mantenimiento a equipos móviles. Los clientes buscan tener un alto porcentaje de disponibilidad que a su vez les garantice una productividad según lo que ellos se proyectaron o inclusive superar esas proyecciones, para ello fue necesario elaborar un plan estratégico capaz de adaptarse a cada una de las exigencias de los diferentes clientes. Se considera como punto de partida la recopilación y análisis la información para luego proponer las mejoraras u oportunidades de desarrollo y así alcanzar los objetivos propuestos. Para lograr dichos objetivos se basó en la metodología TPM y sus 8 pilares, de los cuales se implementaron 3, entre los que tenemos; entrenamiento, mantenimiento planificado y control administrativo, considerando que por cada uno de los pilares implementados se realizaron acciones como son las capacitaciones en actividades del personal técnico, tiempos e insumos, así como la elaboración de documentos para el registro El resultado de mejora en la gestión del mantenimiento se vio reflejado en ser más rentable, mejorar los procesos.The main objective of this TPM implementation work is to improve the management of the planning area of the company JC Electrohidráulicos S.A.C., which provides integrated maintenance service to mobile equipment. Customers seek to have a high percentage of availability that in turn guarantees them productivity depending on what they projected or even exceeded these projections, for this it was necessary to develop a strategic plan capable of adapting to each of the demands of the different clients. It is considered as a starting point the collection and analysis of information and then propose improvements or development opportunities and thus achieve the proposed objectives. To achieve these objectives, it was based on the TPM methodology and its 8 pillars, of which 3 were implemented, among which we have; training, planned maintenance and administrative control, considering that for each of the pillars implemented, actions such as the training in activities of technical staff, times and supplies, as well as the preparation of documents for registration The result of improvement in maintenance management was reflected in being more profitable, improving processes