Cosmological exploitation of cosmic void statistics - New numerical tools in the CosmoBolognaLib to extract cosmological constraints from the void size function

We present new numerical tools to analyse cosmic void catalogues, implemented inside the CosmoBolognaLib, a large set of Open Source C++/Python numerical libraries. The CosmoBolognaLib provides a common numerical environment for cosmological calculations. This work extends these libraries by adding new algorithms for cosmological analyses of cosmic voids, covering the existing gap between theory and observations. We implemented new methods to model the size function of cosmic voids, in both observed and simulated samples of dark matter and biased tracers. Moreover, we provide new numerical tools to construct unambiguous void catalogues. The latter are designed to be independent of the void finder, in order to allow a high versatility in comparing independent results. The implemented Open Source software is available at the GitHub repository https://github.com/federicomarulli/CosmoBolognaLib. We provide also a full doxygen documentation and some example codes that explain how to use these libraries.Comment: 8 pages, 5 figures, reviewed version published in Astronomy & Astrophysic

Discriminación y redes sociales: Popularidad entre los estudiantes de bachillerato en Argentina

El objetivo de este trabajo es adquirir un mejor entendimiento del fenómeno de la popularidad de compañeros de clase durante la adolescencia y detectar señales de discriminación. En Argentina, estudiantes de secundaria seleccionan y clasifican a 10 compañeros de clase con los que les gustaría formar equipo. Se descubrió que los estudiantes físicamente atractivos y de alto rendimiento académico son altamente cotizados por sus compañeros de clase, pero sólo en planteles mixtos, lo que hace pensar que eso responde principalmente al emparejamiento. Otros rasgos, tales como el color de la piel, la nacionalidad y el nivel socioeconómico de los padres, no inciden en la popularidad entre los compañeros de clase, aunque el origen étnico y la formación académica de los padres son estadísticamente significativos en algunos casos. Da la impresión de que el tratamiento desigual basado en la raza, riqueza económica y nacionalidad que hay presente en otros entornos sociales de Argentina no se observa entre los adolescentes que asisten a la escuela.

Pet Loss and Representations of Death, Attachment, Depression, and Euthanasia

T Studies that have examined pet loss hypothesize that attachment, representations of death, and the belief in an afterlife for animals may influence owners\u2019 bereavement and depressive outcomes. The following instruments were administered to 159 Italian participants recruited through snowball sampling: the Lexington Attachment to Pets Scale (LAPS), the Pet Bereavement Questionnaire (PBQ), the Testoni Death Representation Scale (TDRS), and Beck\u2019s Depression Inventory II (BDI-II). Questions concerning pet euthanasia-related issues and the relationship between owners and veterinarians were also submitted to the participants. A path model was conducted, showing that the representation of death and the attachment to a pet had a direct effect on pet grief, which in turn had a direct effect on depression. The results show a positive correlation between the LAPS and PBQ factors, particularly with the PBQ factor Grief. The LAPS factors positively correlated with the TDRS representation of Death as a Passage and negatively correlated with the TDRS representation of Death as Annihilation. The LAPS People Substituting factor positively correlated with the total score and the CognitiveAffective factor of the BDI-II. The PBQ factors positively correlated with the BDI-II, whereas only the TDRS Death as Annihilation factor positively correlated with the BDI-II. Belief in a transcendent dimension was associated with higher scores on the PBQ Guilt factor and the TDRS factors of Death as a Passage and Death as Change, whereas these beliefs were associated with lower scores on the TDRS factor Death as Annihilation. The results indicated that the sensitivity of the veterinarian and a veterinarian who helps owners make conscious and informed decisions for their pet and choose the right time to perform euthanasia are important variables in the management of pet loss. However, these factors are not sufficient and psychological support should be improved to help owners better cope with grief

Enforcement of labor regulations in developing countries

More than half of private sector employees in the developing world do not receive legally mandated labor benefits. These regulations have typically been enacted by democratically elected governments, and are valued by both formal and informal workers. Increasing public enforcement (e.g. inspections, fines, and workers’ access to the judiciary) can be a powerful tool to reduce violations (e.g. increase the number of employees earning above the minimum wage). Which factors determine enforcement, and whether enforcement produces more social benefits than costs, are, however, unanswered questions.Fil: Ronconi, Lucas. Centro de Investigación y Acción Social; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Cosmic voids uncovered -- first-order statistics of depressions in the biased density field

Cosmic voids are the major volume component in the matter distribution of the Universe. They posses great potential for constraining dark energy as well as for testing theories of gravity. Nevertheless, in spite of their growing popularity as cosmological probes, a gap of knowledge between cosmic void observations and theory still persists. In particular, the void size function models proposed in literature have been proven unsuccessful in reproducing the results obtained from cosmological simulations in which cosmic voids are detected from biased tracers of the density field, undermining the possibility of using them as cosmological probes. The goal of this work is to cover this gap. In particular, we make use of the findings of a previous work in which we have improved the void selection procedure, presenting an algorithm that redefines the void ridges and, consequently, their radius. By applying this algorithm, we validate the volume conserving model of the void size function on a set of unbiased simulated density field tracers. We highlight the difference in the internal structure between voids selected in this way and those identified by the popular VIDE void finder. We also extend the validation of the model to the case of biased tracers. We find that a relation exists between the tracer used to sample the underlying dark matter density field and its unbiased counterpart. Moreover, we demonstrate that, as long as this relation is accounted for, the size function is a viable approach for studying cosmology with cosmic voids.Comment: 11 pages, 6 figures, 3 tables, submitted to MNRA

From cosmic voids to collapsed structures: HPC methods for Astrophysics and Cosmology

Computational methods, software development and High Performance Computing awareness are of ever-growing importance in Astrophysics and Cosmology. In this context, the additional challenge comes from the impossibility of reproducing experiments in the controlled environment of a laboratory, making simulations unavoidable for testing theoretical models. In this work I present a quite heterogeneous ensemble of projects we have performed in the context of simulations of the large scale structure of the Universe. The connection being the development and usage of original computational tools for the analysis and post-processing of simulated data. In the first part of this manuscript I report on the efforts to develop a consistent theory for the size function of cosmic voids detected in biased tracers of the density field. Upcoming large scale surveys will map the distribution of galaxies with unprecedented detail and up to depths never reached before. Thanks to these large datasets, the void size function is expected to become a powerful statistics to infer the geometrical properties of space-time. In spite of this, the existing theoretical models are not capable of describing correctly the distribution of voids detected, neither in unbiased nor in biased simulated tracers. We have improved the void selection procedure, by developing an algorithm that redefines the void ridges and, consequently, their radii. By applying this algorithm, we validate the volume conserving model of the void size function on a set of unbiased simulated density field tracers. We highlight the difference in the internal structure between voids selected in this way and those identified by the popular VIDE void finder. We also extend the validation of the model to the case of biased tracers. We find that a relation exists between the tracer used to sample the underlying dark matter density field and its unbiased counterpart. Moreover, we demonstrate that, as long as this relation is accounted for, the size function is a viable approach for studying cosmology with voids. Finally, by parameterising the size function in terms of the linear effective bias of tracers, we perform an additional step towards analysing cosmic voids in real surveys. The proposed size function model has been accurately calibrated on halo catalogues, and used to validate the possibility to provide forecasts on the cosmological constraints, namely on the matter density parameter, $Omega_M$, and on the normalisation of the linear matter power spectrum, $sigma_8$. oindent The second part of the manuscript is focused in presenting the hybrid C++/python implementation of ScamPy, our empirical framework for ``painting'' galaxies on top of the Dark Matter Halo/Sub-Halo hierarchy obtained from N-body simulations. Our confidence on the reliability of N-body Dark Matter-only simulations stands on the argument that the evolution of the non-collisional matter component only depends on the effect of gravity and on the initial conditions. The formation and evolution of the luminous component (i.e. galaxies and intergalactic baryonic matter) are far from being understood at the same level as the dark matter. Among the possible approaches for modelling the luminous component, empirical methods are designed to reproduce observable properties of a target (observed) population of objects at a given moment of their evolution. With respect to ab initio approaches (i.e. hydrodynamical N-body simulations and semi-analytical models), empirical methods are typically cheaper in terms of computational power and are by design more reliable in the high redshift regime. Building an empirical model of galaxy occupation requires to define the hosted-object/hosting-halo connection for associating to the underlying DM distribution its baryonic counterpart. The method we use is based on the sub-halo clustering and abundance matching (SCAM) scheme which requires observations of the 1- and 2-point statistics of the target population we want to reproduce. This method is particularly tailored for high redshift studies and thereby relies on the observed high-redshift galaxy luminosity functions and correlation properties. The core functionalities of ScamPy are written in C++ and exploit Object Oriented Programming, with a wide use of polymorphism, to achieve flexibility and high computational efficiency. In order to have an easily accessible interface, all the libraries are wrapped in python and provided with an extensive documentation. I present the theoretical background of the method and provide a detailed description of the implemented algorithms. We have validated the key components of the framework, demonstrating it produces scientifically meaningful results with satisfying performances. Finally, we have tested the framework in a proof-of-concept application at high-redshift. Namely, we paint a mock galaxy population on top of high resolution dark matter only simulation, mimicking the luminosity and clustering properties of high-redshift Lyman Break Galaxies retrieved from recent literature. We use these mock galaxies to infer the ionizing radiation spatial and statistical distribution during the period of Reionization