Constraints on the cosmological density parameters and cosmic topology

A nontrivial topology of the spatial section of the universe is an observable, which can be probed for all locally homogeneous and isotropic universes, without any assumption on the cosmological density parameters. We discuss how one can use this observable to set constraints on the density parameters of the Universe by using a specific spatial topology along with type Ia supenovae and X-ray gas mass fraction data sets.Comment: 11 pages, 4 figures. To appear in Int. J. Mod. Phys. D (2006). Invited talk delivered at the 2nd International Workshop on Astronomy and Relativistic Astrophysic

A note on the large-angle anisotropies in the WMAP cut-sky maps

Recent analyses of the WMAP data seem to indicate the possible presence of large-angle anisotropy in the Universe. If confirmed, these can have important consequences for our understanding of the Universe. A number of attempts have recently been made to establish the reality and nature of such anisotropies in the CMB data. Among these is a directional indicator recently proposed by the authors. A distinctive feature of this indicator is that it can be used to generate a sky map of the large-scale anisotropies of the CMB maps. Applying this indicator to full-sky temperature maps we found a statistically significant preferred direction. The full-sky maps used in these analyses are known to have residual foreground contamination as well as complicated noise properties. Thus, here we performed the same analysis for a map where regions with high foreground contamination were removed. We find that the main feature of the full-sky analysis, namely the presence of a significant axis of asymmetry, is robust with respect to this masking procedure. Other subtler anomalies of the full-sky are on the other hand no longer present.Comment: 10 pages, 3 figeres. We performed a similar analysis of arXiv:astro-ph/0511666 by considering the LILC map with a Kp2 sky cut, and find that the presence of a significant axis of asymmetry is robust with respect to this masking procedur

Non-Gaussianity in the HILC foreground-reduced three-year WMAP CMB map

A detection or nondetection of primordial non-Gaussianity in the CMB data is essential not only to test alternative models of the physics of the early universe but also to discriminate among classes of inflationary models. Given this far reaching consequences of such a non-Gaussianity detection for our understanding of the physics of the early universe, it is important to employ alternative indicators in order to have further information about the Gaussianity features of CMB that may be helpful for identifying their origins. In this way, a considerable effort has recently gone into the design of non-Gaussianity indicators, and in their application in the search for deviation from Gaussianity in the CMB data. Recently we have proposed two new large-angle non-Gaussianity indicators which provide measures of the departure from Gaussianity on large angular scales. We have used these indicators to carry out analyses of Gaussianity of the single frequency bands and of the available foreground-reduced {\it five-year} maps with and without the KQ75 mask. Here we extend and complement these studies by performing a new analysis of deviation from Gaussianity of the {\it three-year} harmonic ILC (HILC) foreground-reduced full-sky and KQ75 masked maps obtained from WMAP data. We show that this full-sky foreground-reduced maps presents a significant deviation from Gaussianity, which is brought down to a level of consistency with Gaussianity when the KQ75 mask is employed.Comment: 6 pages, 1 figure. To appear in IJMPD (2010). V2: Corrected ref.[8]

Constraints on dark energy and cosmic topology

A non-trivial spatial topology of the Universe is a potentially observable attribute, which can be probed through the circles-in-the-sky for all locally homogeneous and isotropic universes with no assumptions on the cosmological parameters. We show how one can use a possible circles-in-the-sky detection of the spatial topology of globally homogeneous universes to set constraints on the dark energy equation of state parameters.Comment: 6 pages, 1 figure. To appear in Int. J. Mod. Phys. A (2009). From a talk presented at the Seventh Alexander Friedmann International Seminar on Gravitation and Cosmolog

Observational constraints on modified gravity models and the Poincar\'e dodecahedral topology

We study the constraints that spatial topology may place on the parameters of models that account for the accelerated expansion of the universe via infrared modifications to general relativity, namely the Dvali-Gabadadze-Porrati braneworld model as well as the Dvali-Turner and Cardassian models. By considering the Poincar\'e dodecahedral space as the circles-in-the-sky observable spatial topology, we examine the constraints that can be placed on the parameters of each model using type Ia supernovae data together with the baryon acoustic peak in the large scale correlation function of the Sloan Digital Sky Survey of luminous red galaxies and the Cosmic Microwave Background Radiation shift parameter data. We show that knowledge of spatial topology does provide relevant constraints, particularly on the curvature parameter, for all models.Comment: Revtex4, 10 pages, 1 table, 12 figures; version to match the one to be published in Physical Review

Detectability of Cosmic Topology in Generalized Chaplygin Gas Models

If the spatial section of the universe is multiply connected, repeated images or patterns are expected to be detected observationally. However, due to the finite distance to the last scattering surface, such pattern repetitions could be unobservable. This raises the question of whether a given cosmic topology is detectable, depending on the values of the parameters of the cosmological model. We study how detectability is affected by the choice of the model itself for the matter-energy content of the universe, focusing our attention on the generalized Chaplygin gas (GCG) model for dark matter and dark energy unification, and investigate how the detectability of cosmic topology depends on the GCG parameters. We determine to what extent a number of topologies are detectable for the current observational bounds on these parameters. It emerges from our results that the choice of GCG as an alternative to the $\Lambda$CDM matter-energy content model has an impact on the detectability of cosmic topology.Comment: Submitted to A&

The reverse of subject: Foucault’s provocations to think about human rights

Este ensayo pretende discutir los modos de subjetivación propuestos por Michel Foucault y los derechos humanos. Tomando esas implicaciones Faucaultianas del cuidado de sí mismo y de una estilización de la existencia de la constitución en nuestras vidas, es posible substituir el llamado a lo universal y lo esencial por formas más disonantes de subjetivación, significativamente más singulares. Este ensayo se enfocó en un referencial bibliográfico que contempla obras de Foucault y obras sobre el autor, sobre derechos humanos, sin perder de vista las implicaciones practicas y las experiencias del campo jurídico. Sin embargo, la percepción de las insuficiencias de la teoría tradicional de los derechos humanos de encarar las diferencias de la subjetividad y de promover la autonomía y la emancipación de los sujetos, evidencia el motivo por el cual buscamos elementos nuevos de la subjetividad en la filosofía de Foucault y en una teoría critica de los derechos humanos..This paper aims to discuss the forms of subjectivation as proposed by Michael Foucault and the human rights. Taking as a starting point the Foucaultian im­plications of “the care of the self” and of “the stylization of existence” in the constitution of our lives, it is possible to replace the figures of the universal and the essential by more dissonant and singular forms of subjectivation. The essay corpus is focused in a bibliography that contemplates works by and about Michael Foucault and works about human rights without loosing sight of the practical implications and experiences in the field of law. More over, the per­ception of the deficiencies of the traditional theory about human rights when confronted with subjective differences or the need to promote autonomy and emancipation of the subjects shows why we seek new elements of subjectivity in Foucault’s philosophy and in a critical theory of human rights.Este ensaio pretende discutir os modos de subjetivação propostos por Michel Foucault e os direitos humanos. Tomando as implicações Foucaultianas do cuidado de si e de uma estilização da existência na constituição de nossas vidas, é possível substituir o apelo ao universal e ao essencial por formas mais dissonantes de subjetivação, significativamente mais singulares. O corpus deste ensaio concentrou-se num referencial bibliográfico que contempla obras de Foucault e sobre o autor, sobre direitos humanos, sem perder de vista as implicações práticas e as experiências do campo jurídico. Mais ainda, a percepção das insuficiências da teoria tradicional dos direitos humanos de encarar as diferenciações da subjetividade e de promover a autonomia e a emancipação dos sujeitos evidencia o motivo pelo qual buscamos elementos novos da subjetividade na filosofia de Foucault e em uma teoria crítica dos direitos humano

Generalized Chaplygin gas model, supernovae and cosmic topology

In this work we study to which extent the knowledge of spatial topology may place constraints on the parameters of the generalized Chaplygin gas (GCG) model for unification of dark energy and dark matter. By using both the Poincar\'e dodecahedral and binary octahedral spaces as the observable spatial topologies, we examine the current type Ia supernovae (SNe Ia) constraints on the GCG model parameters. We show that the knowledge of spatial topology does provide additional constraints on the $A_s$ parameter of the GCG model but does not lift the degeneracy of the $\alpha$ parameter.Comment: Revtex 4, 8 pages, 10 figures, 1 table; version to match the published on