Isolated horizons in numerical relativity: constructing the excised Kerr spacetime in Dirac gauge

Using a constrained formalism for Einstein equations in Dirac gauge, we propose to compute excised quasistationary initial data for black hole spacetimes in full general relativity. Vacuum spacetime settings are numerically constructed by using the isolated horizon formalism; we especially tackle the conformal metric part of our equations, assuming global stationarity. We show that a no-boundary treatment can be used on the horizon for the equation related to the conformal metric. We relate this finding to previous suggestions in the literature, and use our results to assess the widely used conformally flat approximation for computing black hole initial data.Comment: 3 pages, 1 figure; to appear in the proceedings of the 12th Marcel Grossmann meeting on general relativit

Guarding the border: watchtowers of the Nasrid Kingdom of Granada. Characterization and vulnerability assessment

RUIZ-JARAMILLO, J. y GARCÍA-PULIDO, L.J., 2018. Guarding the border: watchtowers of the Nasrid Kingdom of Granada. Characterization and vulnerability assessment. Heritage 2018: 6th International Conference on Heritage and Sustainable Development. Granada: Green Lines Institute for Sustainable Development, pp. 1511-1518The Islamic Nasrid kingdom of Granada occupied the mountainous areas of the south-eastern of the Iberian Peninsula. The frontier between the Nasrid kingdom and the Christian kingdom of Castile from 1232 to 1492 was controlled by an extensive network of watchtowers built by Nasrid through the provinces of Granada, Malaga, Almeria and the eastern parts of Jaen, Cordoba and Cadiz. They allowed controlling this frontier stablishing visual communication between them and the Nasrid centre at the Alhambra citadel. Even protected by Spanish Heritage law, many of these medieval towers and their cultural landscapes are in severe risk be-cause of anthropic action as well as natural deterioration. Within the framework of the R&D project called ‘Las atalayas que defendieron el reino nazarí de Granada. Análisis y docu-mentación científica (Nazalaya)”, the towers are being studied. As a complement of planimetry obtained by procedures as photogrammetry or terrestrial laser scanning (TLS), complete architectural surveys using non-destructive techniques are being performed as part of the analysis to obtain a global description of construction systems used.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Muslim heritage and environment: the case of the watchtowers of the nasrid kingdom of Granada (thirteenth to fifteenth century)

Luis José García-Pulido y Jonathan Ruiz-Jaramillo. “Muslim heritage and environment: the case of the watchtowers of the nasrid kingdom of Granada (thirteenth to fifteenth century)”. En: Heritage 2018. Proceedings of the 6th International Conference on Heritage and Sustainable Development (10th Anniversary Edition) Granada, Spain, 12-15 June 2018. Edited by Rogério Amoêda, Sérgio Lira, Cristina Pinheiro, Juan M. Santiago Zaragoza, Julio Calvo Serrano, Fabián García Carrillo. Editorial Universidad de Granada y Green Lines Institute for Sustainable Development, Granada, 2018. e-ISBN 978-84-338-6261-7This paper is devoted to the study of the different towers of the Nasrid kingdom of Granada (1232 to 1492) and their linked landscapes, as well as the evolution, preservation, resilience or transformation of their environment until present days. These late Islamic territories in medieval Iberia occupied the mountainous areas of the southeastern area of today’s Spain. There, a natural border was established between the Nasrid kingdom and the expansion of Castile during more than two centuries and a half. To control this frontier and establish visual communication between it and the Nasrid power centres lead by the Alhambra citadel, an extensive network of watchtowers and defensive towers linked to farmsteads was constructed. These towers are located in unique sites; being erected as reference landmarks of the territories on which they stand. These fortifications, with very diverse typology and morphology, are a faithful testimony to the different territorial structure that has taken place throughout history.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. This paper has been written within the framework of the Spanish Proyecto del Plan Nacional I+D+i (Programa Estatal de Fomento de la Investigación Científica y Técnica de Excelencia) entitled ‘Las atalayas que defendieron el reino nazarí de Granada. Análisis y documentación científica (Nazalaya)’ (‘The watchtowers that defended the nasrid kingdom of Granada. Analysis and scientific survey’, HAR2016-79689-P), directed by PhD Luis José García-Pulido and PhD Jonathan Ruiz Jaramillo. This contribution is also been framed within the projects ‘La construcción de un paisaje: arquitectura de tapial en la Alta Andalucía en el siglo XIII. Estudio y análisis del sistema de torres andalusíes en el valle de Segura de la Sierra’ (‘The building of a Landscape: rammed earth architecture in High Andalusia during the thirteenth century. Analysis of the andalusí tower system in the Segura de la Sierra valley’, Proyecto de Investigación Precompetitivo (mod. A) from the Plan Propio de la Universidad de Málaga), and ‘Torres medievales y modernas conservadas en Andalucía. Documentación gráfica, análisis científico e interrelaciones’ (‘Medieval and Modern towers preserved in Andalusia. Graphical survey, scientific analysis and interrelations’, X Convocatoria de Proyectos de Investigación de la Fundación Pública Andaluza Centro de Estudios Andaluces en la modalidad de proyectos individuales, PRY/259/17)

Pseudospectrum and binary black hole merger transients

The merger phase of binary black hole coalescences is a transient between an initial oscillating regime (inspiral) and a late exponentially damped phase (ringdown). In spite of the non-linear character of Einstein equations, the merger dynamics presents a surprisingly simple behaviour consistent with effective linearity. On the other hand, energy loss through the event horizon and by scattering to infinity renders the system non-conservative. Hence, the infinitesimal generator of the (effective) linear dynamics is a non-selfadjoint operator. Qualitative features of transients in linear dynamics driven by non-selfadjoint (in general, non-normal) operators are captured by the pseudospectrum of the time generator. We propose the pseudospectrum as a unifying framework to thread together the phases of binary black hole coalescences, from the inspiral-merger transition up to the late quasinormal mode ringdown.Comment: 18 pages, 1 figur

El cuerpo humano y su empleo como evidencia probatoria

Legitimado el Estado para el ejercicio de la actividad penal en toda su dimensión, esto es, imposición de la pena, obligación de probar responsabilidad, si se dice ser ESTADO SOCIAL DE DERECHO FUNDADO EN EL RESPETO A LA DIGNIDAD HUMANA, no puede ese Estado, amparado en la idea de eficacia de la Administración de Justicia, utilizar al hombre y su cuerpo, SIN SU CONSENTIMIENTO, como evidencia probatoria; lo contrario conduciría ineludiblemente al irrespeto de la dignidad humana "como al irrespeto por sus derechos humanos fundamentales

Numerical implementation of isolated horizon boundary conditions

We study the numerical implementation of a set of boundary conditions derived from the isolated horizon formalism, and which characterize a black hole whose horizon is in quasi-equilibrium. More precisely, we enforce these geometrical prescriptions as inner boundary conditions on an excised sphere, in the numerical resolution of the Conformal Thin Sandwich equations. As main results, we firstly establish the consistency of including in the set of boundary conditions a "constant surface gravity" prescription, interpretable as a lapse boundary condition, and secondly we assess how the prescriptions presented recently by Dain et al. for guaranteeing the well-posedness of the Conformal Transverse Traceless equations with quasi-equilibrium horizon conditions extend to the Conformal Thin Sandwich elliptic system. As a consequence of the latter analysis, we discuss the freedom of prescribing the expansion associated with the ingoing null normal at the horizon.Comment: 11 pages, 5 figures, references added and correcte

An excision scheme for black holes in constrained evolution formulations: spherically symmetric case

Excision techniques are used in order to deal with black holes in numerical simulations of Einstein equations and consist in removing a topological sphere containing the physical singularity from the numerical domain, applying instead appropriate boundary conditions at the excised surface. In this work we present recent developments of this technique in the case of constrained formulations of Einstein equations and for spherically symmetric spacetimes. We present a new set of boundary conditions to apply to the elliptic system in the fully-constrained formalism of Bonazzola et al. (2004), at an arbitrary coordinate sphere inside the apparent horizon. Analytical properties of this system of boundary conditions are studied and, under some assumptions, an exponential convergence toward the stationary solution is exhibited for the vacuum spacetime. This is verified in numerical examples, together with the applicability in the case of the accretion of a scalar field onto a Schwarzschild black hole. We also present the successful use of the excision technique in the collapse of a neutron star to a black hole, when excision is switched on during the simulation, after the formation of the apparent horizon. This allows the accretion of matter remaining outside the excision surface and for the stable long-term evolution of the newly formed black hole.Comment: 14 pages, 9 figures. New section added and changes included according to published articl