A new perspective on the evolution of galaxies : from global to local scales

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física Teórica. Fecha de lectura: 24-11-2016This thesis dissertation addresses the topic of galaxy formation and evolution with the main purpose of shedding some light on the main mechanism(s) responsible for the selfregulation of the star formation activity in the nearby Universe. As a first step, we revisit the classic “nature or nurture” debate in this context by using a sample of 82000 objects extracted from the Sloan Digital Sky Survey. Our analysis crosscorrelates two proxies of the specific star formation rate, the equivalent width (EW) of the H line and the (u-r) colour, with other physical properties (mass, metallicity, environment, morphology, and the presence of close companions) leading to the discovery of a relatively tight “ageing sequence” in the colour–EW plane. This trend favours a scenario where the secular conversion of gas into stars (i.e. nature) is the main physical driver of star formation and the gradual transition from a “chemically primitive” (metal-poor and intensely starforming) state to a “chemically evolved” (metal-rich and passively-evolving) system. To address the dependence on local and global properties, we investigate in further detail the resolved colour-EW diagram of 40 matching objects from the CALIFA survey. The IFS data reveal that the smooth “ageing” process always takes place, inside-out (i.e. the central parts are more evolved than the outskirts), across the entire extent of all galaxies. The current state of the different regions seems to be mostly driven by local processes, albeit global properties (in particular, galaxy morphology) may play an important role. The analysis of low signal-to-noise (S/N) measurements was critical in order to reach these conclusions. To make an optimal use of this valuable information, we developed the Bayesian Technique for Multi-image Analysis (BaTMAn) algorithm for the segmentation of multidimensional data, with emphasis on the statistically-meaningful binning of IFS observations. When applied to our dataset, the method significantly reduces the scatter in the colour-EW diagram, convincingly demonstrating that there may be different ageing paths depending on the details of the local star formation history. In our view, the new generation of IFS surveys calls for new analysis tools and methodologies, and a rigorous assessment of their accuracy (and that of the associated errors!) requires a battery of realistic test cases where the correct solution is known. The final part of this thesis describes the production of synthetic IFS observations, with similar characteristics to the CALIFA products, based on hydrodynamical simulations. This ongoing project will allow us to explore the optimal strategy to study galaxy ageing from current and forthcoming IFS data, and it will provide the scientific community with a powerful tool to test their analysis pipelines

New Directions for Contact Integrators

Contact integrators are a family of geometric numerical schemes which guarantee the conservation of the contact structure. In this work we review the construction of both the variational and Hamiltonian versions of these methods. We illustrate some of the advantages of geometric integration in the dissipative setting by focusing on models inspired by recent studies in celestial mechanics and cosmology.Comment: To appear as Chapter 24 in GSI 2021, Springer LNCS 1282

Revisiting Component Tree Based Segmentation Using Meaningful Photometric Informations

International audienceThis paper proposes to revisit a recent interactive segmentation algorithm based on an original image representation called the component-tree [1]. This method relies on an optimisation process allowing to choose a segmentation result fitting at best some image markers defined by the user. We propose different solutions to improve the efficiency of the method, in particular by including meaningful photometric informations and by assessing automatically the user parameter α

Across Space and Time. Papers from the 41st Conference on Computer Applications and Quantitative Methods in Archaeology, Perth, 25-28 March 2013

This volume presents a selection of the best papers presented at the forty-first annual Conference on Computer Applications and Quantitative Methods in Archaeology. The theme for the conference was "Across Space and Time", and the papers explore a multitude of topics related to that concept, including databases, the semantic Web, geographical information systems, data collection and management, and more

Safety and Reliability - Safe Societies in a Changing World

The contributions cover a wide range of methodologies and application areas for safety and reliability that contribute to safe societies in a changing world. These methodologies and applications include: - foundations of risk and reliability assessment and management - mathematical methods in reliability and safety - risk assessment - risk management - system reliability - uncertainty analysis - digitalization and big data - prognostics and system health management - occupational safety - accident and incident modeling - maintenance modeling and applications - simulation for safety and reliability analysis - dynamic risk and barrier management - organizational factors and safety culture - human factors and human reliability - resilience engineering - structural reliability - natural hazards - security - economic analysis in risk managemen

MS FT-2-2 7 Orthogonal polynomials and quadrature: Theory, computation, and applications

Quadrature rules find many applications in science and engineering. Their analysis is a classical area of applied mathematics and continues to attract considerable attention. This seminar brings together speakers with expertise in a large variety of quadrature rules. It is the aim of the seminar to provide an overview of recent developments in the analysis of quadrature rules. The computation of error estimates and novel applications also are described

Generalized averaged Gaussian quadrature and applications

A simple numerical method for constructing the optimal generalized averaged Gaussian quadrature formulas will be presented. These formulas exist in many cases in which real positive GaussKronrod formulas do not exist, and can be used as an adequate alternative in order to estimate the error of a Gaussian rule. We also investigate the conditions under which the optimal averaged Gaussian quadrature formulas and their truncated variants are internal

Proceedings of the NASA Conference on Space Telerobotics, volume 3

The theme of the Conference was man-machine collaboration in space. The Conference provided a forum for researchers and engineers to exchange ideas on the research and development required for application of telerobotics technology to the space systems planned for the 1990s and beyond. The Conference: (1) provided a view of current NASA telerobotic research and development; (2) stimulated technical exchange on man-machine systems, manipulator control, machine sensing, machine intelligence, concurrent computation, and system architectures; and (3) identified important unsolved problems of current interest which can be dealt with by future research