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Radiation induced by relativistic electron showers in the X-ray spectrum of Active Galactic Nuclei

The iron Kα emitted from accreting black holes is thought to be produced by the reprocessing of hard X-ray radiation illuminating the disk. Mechanisms which could produce this hard X-ray radiation are magnetic reconnection in the disk corona or shocks. Both phenomena produce high energy particles whose contribution is usually ignored. In this work, we analyze how the transfer of mechanical energy from relativistic electrons to the circumnuclear gas (accretion disk, BLR) contributes to the X-ray continuum and the iron Kα emission. It is shown that for gas columns comparable to the Thomson depth, the iron Kα yield is comparable to that observed provided that the electron energy is above ∼600 keV and that the total kinetic luminosity of the beam is around log LKIN = 46.6−47.7; this luminosity is comparable to that observed in radio-loud AGNs. The photon index of the X-ray continuum (8 keV−20 keV) generated in such an electron shower is 1 ≤ Γ ≤ 2. Γ and the continuum strength are strongly model-dependent; they are dependent on both the relative orientation between the electron beam and the observer and the radius of the electron beam compared with the characteristic radius of the absorbing medium. The relevance of particle energy transport compared to photon energy transport in the AGN environment is outlined.Peer reviewe

Seguimiento de estudiantes y egresados en los Dobles Grados de Matemáticas

El proyecto tiene carácter interfacultativo e incluye a las facultades de CC. Económicas y Empresariales, Ciencias Físicas, Informática y Ciencias Matemáticas. Es una continuación natural del PIMCD-287 “Elaboración de estudios para el seguimiento del rendimiento académico de los estudiantes de los dobles grados en Matemáticas”. El objetivo global del proyecto ha consistido en el de avanzar en el trabajo iniciado con el proyecto anterior concedido en el curso 2014-15 y profundizar en el análisis de las distintas acciones que se han llevado a cabo a través de las encuestas realizadas al alumnado, reuniones y el debate sobre aprendizaje/evaluación continua en Grados y dobles Grados. Se continuó con la revisión del modelo de coordinación horizontal académico-docente, con el fin de dotarlo de una mayor eficacia

Automated Network Service Scaling in NFV: Concepts, Mechanisms and Scaling Workflow

Next-generation systems are anticipated to be digital platforms supporting innovative services with rapidly changing traffic patterns. To cope with this dynamicity in a cost-efficient manner, operators need advanced service management capabilities such as those provided by NFV. NFV enables operators to scale network services with higher granularity and agility than today. For this end, automation is key. In search of this automation, the European Telecommunications Standards Institute (ETSI) has defined a reference NFV framework that make use of model-driven templates called Network Service Descriptors (NSDs) to operate network services through their lifecycle. For the scaling operation, an NSD defines a discrete set of instantiation levels among which a network service instance can be resized throughout its lifecycle. Thus, the design of these levels is key for ensuring an effective scaling. In this article, we provide an overview of the automation of the network service scaling operation in NFV, addressing the options and boundaries introduced by ETSI normative specifications. We start by providing a description of the NSD structure, focusing on how instantiation levels are constructed. For illustrative purposes, we propose an NSD for a representative NS. This NSD includes different instantiation levels that enable different ways to automatically scale this NS. Then, we show the different scaling procedures the NFV framework has available, and how it may automate their triggering. Finally, we propose an ETSI-compliant workflow to describe in detail a representative scaling procedure. This workflow clarifies the interactions and information exchanges between the functional blocks in the NFV framework when performing the scaling operation.Comment: This work has been accepted for publication in the IEEE Communications Magazin