A magnetic reconnection model for explaining the multi-wavelength emission of the microquasars Cyg X-1 and Cyg X-3

Recent studies have indicated that cosmic ray acceleration by a first-order Fermi process in magnetic reconnection current sheets can be efficient enough in the surrounds of compact sources. In this work, we discuss this acceleration mechanism operating in the core region of galactic black hole binaries (or microquasars) and show the conditions under which this can be more efficient than shock acceleration. In addition, we compare the corresponding acceleration rate with the relevant radiative loss rates obtaining the possible energy cut-off of the accelerated particles and also compute the expected spectral energy distribution (SED) for two sources of this class, namely Cygnus X-1 and Cygnus X-3, considering both leptonic and hadronic processes. The derived SEDs are comparable to the observed ones in the low and high energy ranges. Our results suggest that hadronic non-thermal emission due to photo-meson production may produce the very high energy gamma-rays in these microquasars.Comment: 17 pages and 7 figures. Accepted for publication in the Monthly Notices of the Royal Astronomical Society (MNRAS

Liderazgo de ambientes seguros que ayudan a crecer : directivos

El terremoto ocurrido en el norte de Chile provocó un estado de emergencia que afectó de manera integral nuestra existencia como personas y como comunidad. En una primera instancia, dicha situación requirió ser abordada con apoyos y acciones de resguardo de la integridad vital, atención de necesidades de alimentación, seguridad, vivienda, de salud física y mental, de conectividad y comunicaciones. El material fue preparado para el desarrollo de espacios de contención y apoyo emocional y la creación de ambientes de respeto, confianza, prevención y autocuidado, tanto dentro como fuera del aula. También busca estimular y motivar la realización de actividades de auto conocimiento, reflexión y expresión de las emociones, de las propias ideas y de las maneras diferentes que tenemos todos y todas de reaccionar

AE Aurigae: first detection of non-thermal X-ray emission from a bow shock produced by a runaway star

Runaway stars produce shocks when passing through interstellar medium at supersonic velocities. Bow shocks have been detected in the mid-infrared for several high-mass runaway stars and in radio waves for one star. Theoretical models predict the production of high-energy photons by non-thermal radiative processes in a number sufficiently large to be detected in X-rays. To date, no stellar bow shock has been detected at such energies. We present the first detection of X-ray emission from a bow shock produced by a runaway star. The star is AE Aur, which was likely expelled from its birthplace by the encounter of two massive binary systems and now is passing through the dense nebula IC 405. The X-ray emission from the bow shock is detected at 30" to the northeast of the star, coinciding with an enhancement in the density of the nebula. From the analysis of the observed X-ray spectrum of the source and our theoretical emission model, we confirm that the X-ray emission is produced mainly by inverse Compton upscattering of infrared photons from dust in the shock front.Comment: Accepted for publication in the Astrophysical Journal with number ApJ, 757, L6. Four figure

Defective transport properties of three-terminal carbon nanotube junctions

We investigate the transport properties of three terminal carbon based nanojunctions within the scattering matrix approach. The stability of such junctions is subordinated to the presence of nonhexagonal arrangements in the molecular network. Such "defective" arrangements do influence the resulting quantum transport observables, as a consequence of the possibility of acting as pinning centers of the correspondent wavefunction. By investigating a fairly wide class of junctions we have found regular mutual dependencies between such localized states at the carbon network and a strikingly behavior of the conductance. In particular, we have shown that Fano resonances emerge as a natural result of the interference between defective states and the extended continuum background. As a consequence, the currents through the junctions hitting these resonant states might experience variations on a relevant scale with current modulations of up to 75%.Comment: 8 pages, 8 figure

A model for the repeating FRB 121102 in the AGN scenario

Context. Fast radio bursts (FRBs) are transient sources of unknown origin. Recent radio and optical observations have provided strong evidence for an extragalactic origin of the phenomenon and the precise localization of the repeating FRB 121102. Observations using the Karl G. Jansky Very Large Array (VLA) and very-long-baseline interferometry (VLBI) have revealed the existence of a continuum non-thermal radio source consistent with the location of the bursts in a dwarf galaxy. All these new data rule out several models that were previously proposed, and impose stringent constraints to new models. Aims. We aim to model FRB 121102 in light of the new observational results in the active galactic nucleus (AGN) scenario. Methods. We propose a model for repeating FRBs in which a non-steady relativistic e±-beam, accelerated by an impulsive magnetohydrodynamic driven mechanism, interacts with a cloud at the centre of a star-forming dwarf galaxy. The interaction generates regions of high electrostatic field called cavitons in the plasma cloud. Turbulence is also produced in the beam. These processes, plus particle isotropization, the interaction scale, and light retardation effects, provide the necessary ingredients for short-lived, bright coherent radiation bursts. Results. The mechanism studied in this work explains the general properties of FRB 121102, and may also be applied to other repetitive FRBs. Conclusions. Coherent emission from electrons and positrons accelerated in cavitons provides a plausible explanation of FRBs.Instituto Argentino de RadioastronomíaFacultad de Ciencias Astronómicas y Geofísica

Luminescence Spectra of Quantum Dots in Microcavities. I. Bosons

We provide a unified theory of luminescence spectra of coupled light-matter systems realized with semiconductor heterostructures in microcavities, encompassing: i) the spontaneous emission case, where the system decays from a prepared (typically pure) initial state, and ii) luminescence in the presence of a continuous, incoherent pump. While the former case has been amply discussed in the literature (albeit mainly for the case of resonance), no consideration has been given to the influence of the incoherent pump. We show how, by provoking a self-consistent quantum state, the pump considerably alters the emission spectra, even at vanishing intensities. The main outcome of our analysis is to unambiguously identify strong-coupling in situations where it appears in disguise or only seems to appear. Here, we consider bosonic matter fields, in which case fully analytical solutions can be obtained. This describes the case of quantum wells or large quantum dots, or the limit of low excitation where the average populations remain much smaller than one

Lifestyle and fat distribution in asthmatic and healthy adolescents

Introducción: el objetivo es analizar el estilo de vida, en función del ejercicio y la dieta, de un grupo de adolescentes de la Comunidad de Madrid, teniendo en cuenta género y patología y su relación con el estado nutricional, la distribución de grasa y la función pulmonar. Metodología: Estudio descriptivo de 207 sujetos que analizó el estilo de vida a partir del nivel de actividad física (AF) y la adherencia a la dieta mediterránea, el estado nutricional y la distribución de grasa, y la salud respiratoria. Resultados: El grupo de no asmáticos fue más activo (p=0,003) y presentó menor ICT (p=0,001) que el grupo de asmáticos. Se encontraron diferencias significativas dentro del grupo sin asma en nivel de AF siendo los varones más activos (p=0,01) y presentando menor índice cintura-talla (ICT) que las mujeres del mismo grupo (p=0,001). Conclusiones: Los adolescentes no asmáticos fueron más activos y presentaron mejor distribución de grasa que los asmáticosObjectives: objective is to analyze the lifestyle, integrating exercise and diet, of a group of adolescents from the Community of Madrid, taking into account gender and pathology and its relationship with nutritional status, fat distribution and lung function in adolescents with or without asthma. Methods: This was a descriptive study including 207 subjects aged 13.20 ± 0.62 years. Lifestyle was assessed in terms of physical activity (PA) levels, Mediterranean diet, nutritional status, and respiratory health measured through FEV1 (z). Results: In the non-asthma group, boys were more active (p = 0.01) and showed a lower waist-to-height ratio (WHtR) than girls (p = 0.001). Participants without asthma were more active (p = 0.003), and had a better WHtR (p = 0.001) and FEV1 (p = 0.001) than those with asthma. Conclusions: In this Spanish population sample, non-asthmatic adolescents were more active and showed a better nutritional status, fat distribution and respiratory health than their peers with asthmaFinanciado a través de la VII Convocatoria Real Madrid-Universidad Europea (Ref 2015/03RM); Tercer premio en los XV Premios Neumomadrid; Beca Jóvenes Investigadores de la SENP 2015

D meson nuclear modification factors in Pb-Pb collisions at {\surd}sNN = 2.76 TeV, measured with the ALICE detector

The ALICE experiment has measured the D meson production in pp and Pb-Pb collisions at the LHC at {\surd}s = 7 and 2.76 TeV and {\surd}sNN = 2.76 TeV respectively, via the exclusive reconstruction of hadronic decay channels. The analyses of the D0{\to}K-pi+ and D+{\to}K-pi+pi+ channels will be described and the preliminary results for the D0 and D+ nuclear modification factor will be presented.Comment: Proceedings of Quark Matter 2011 conference. 4 pages, 4 figures. The slides of the talk can be found at the link: http://indico.cern.ch/materialDisplay.py?contribId=591&sessionId=53&materialId=slides&confId=3024