Found 59 talks archived in Particle astrophysics, physical data and processes

Video
Thursday April 28, 2011
Dr. Alberto Dominguez Diaz
Instituto de Astrofísica de Andalucia, Spain

Abstract

The extragalactic background light (EBL) is of fundamental importance both for understanding the entire process of galaxy evolution and for gamma-ray astronomy, but the overall spectrum of the EBL between 0.1 and 1000 microns has never been determined directly from galaxy spectral energy distribution (SED) observations over a wide redshift range. Galaxy SED-type fractions from z=0.2-1 are estimated from a multi-wavelength sample from the AEGIS collaboration that allows a new determination of the evolving EBL. Then, the transparency of the Universe to very high energy (VHE) gamma-ray photons is derived. We find the maximum transparency of the Universe allowed by the standard framework. This result challenges current VHE observations of high redshift blazars. A solution to this problem is discussed utilizing VHE spectra of the highest redshift blazars assuming the existence of a plausible dark matter candidate known as axion-like particle.


Video
Friday April 8, 2011
Dr. Javier Tejada Palacios
Catedrático de física de la materia condensada, Universidad de Barcelona

Abstract

En mi conferencia haré una introducción a la Física Cuántica y a continuación pasaré a discutir diferentes casos en los que los fenómenos cuánticos juegan un papel determinante en el trabajo de diferentes máquinas médicas. De hecho, los ejemplos que explicaré recorrerán la historia de la medicina moderna, la del siglo XX, desde el punto de vista de la terapia como de la inspección. Para todo ello tendré que echar mano, por ejemplo, del principio de incertidumbre de Heisenberg, del efecto túnel de la corriente eléctrica y del espín, de la resonancia atómica. Todo ello para explicar, entre otros casos, cómo se “ve” el corazón, cómo se detectan los pensamientos, porque el feto de la madre roba el oxígeno a la sangre de su madre para poder vivir.


Video
Thursday April 7, 2011
Dr. Antonio Acín
ICFO-Instituto de Ciencias Fotónicas, Barcelona, Spain

Abstract

El azar es un concepto fascinante que atrae el interés de diversas comunidades, desde filósofos a físicos y matemáticos. Por otro lado, los números aleatorios se han convertido en un recurso de gran utilidad práctica, puesto que son utilizados en, por ejemplo, aplicaciones criptográficas o la simulación de sistemas físicos y biológicos. Hasta ahora, cualquier propuesta para la generación de números aleatorios adolece de los siguientes problemas: (i) certificación: ¿cómo se puede probar que los números generados son aleatorios?, (ii) privacidad: ¿cómo se puede garantizar que los números aleatorios son aleatorios, en el sentido de impredecibles, a cualquier otro observador externo y (iii) device-independent: ¿cómo afectan las imperfecciones en los dispositivos al proceso de generación de azar? En la charla se presentará un nuevo formalismo para la generación de azar que resuelve estos tres problemas: por medio de las correlaciones no-locales de los estados entrelazados, es posible generar números cuya aleatoriedad es certificable, privada e independiente de los dispositivos.


Video
Thursday April 7, 2011
Dr. María Jesús Martínez
Instituto de Astrofísica de Canarias, Spain

Abstract

This question is important because a large fraction of planetary nebulae (about 80%) are bipolar or elliptical rather than spherically symmetric. Modern theories invoke magnetic fields, among other causes, to explain the rich variety of aspherical components observed in PNe, as ejected matter is trapped along magnetic field lines. But, until recently, this idea was mostly a theoretical claim. Jordan et al. (2005) report the detection of kG magnetic fields in the central star of two non-spherical PNe, namely NGC1360 and LSS1362. We find that, contrary to that work, the magnetic field is null within errors for both stars. Then, a direct evidence of magnetic fields on the central stars of PNe is still missing — either the magnetic field is much weaker (< 600 G) than previously reported, or more complex (thus leading to cancellations), or both. The role of magnetic fields shaping PNe is still an open question.


Video
Thursday April 7, 2011
Dr. Manuel Aguilar Benítez de Lugo
CIEMAT, CERN

Abstract

El estudio de la radiación cósmica ha sido la herramienta fundamental para avanzar en el conocimiento del Universo. La instrumentación experimental ha sido muy variada utilizándose para su ubicación laboratorios convencionales, globos sonda, satélites y plataformas espaciales. Está previsto que en 2011 la Estación Espacial Internacional esté totalmente operativa y disponible para la realización de medidas precisas y de larga duración de las componentes electromagnética y cargada de la radiación cósmica en ausencia de contaminación atmosférica. Una colaboración internacional ha construido un detector de física de partículas elementales, el espectrómetro AMS−02, para la realización de este tipo de medidas, algunas de las cuales tienen extraordinario interés en Astrofísica de Partículas, una disciplina científica fronteriza entre la Física de Partículas Elementales, la Astrofísica de Altas Energías y la Cosmología. En la planificación de la NASA este instrumento será enviado a la Estación Espacial en el año 2011. En esta conferencia se describirá la Estación Espacial Internacional (ISS) y el programa científico de AMS−02, en particular la búsqueda de antimateria cósmica primaria y la posible observación de señales de materia oscura.


Video
Tuesday March 1, 2011
Dr. Karsten Berger
Instituto de Astrofísica de Canarias, Spain

Abstract

3C 279, the first quasar discovered to emit VHE gamma-rays by the MAGIC telescope in 2006, was re-observed by MAGIC in January 2007 during a major optical flare and from December 2008 to April 2009 following an alert from the Fermi space telescope on an exceptionally high gamma -ray state. The January 2007 observations resulted in a detection on January 16 with significance 5.2 sigma, corresponding to a F(> 150 GeV)(3.8±0.8) 10^-11 ph cm-2 s-1 while the overall data sample does not show significant signal. The December 2008 - April 2009 observations did not detect the source. We study the multi-wavelength behaviour of the source at the epochs of MAGIC observations, collecting quasi-simultaneous data at optical and X-ray frequencies and for 2009 also gamma-ray data from Fermi. We study the light curves and spectral energy distribution of the source. The spectral energy distributions of three observing epochs (including the February 2006, which has been previously published in Albert et al. 2008a) are modelled with one-zone inverse Compton models and the emission on January 16, 2007 also with two zone model and with a lepto-hadronic model. We find that the VHE gamma-ray emission detected in 2006 and 2007 challenges standard one-zone model, based on relativistic electrons in a jet scattering broad line region photons, while the other studied models fit the observed spectral energy distribution more satisfactorily.


Video
Thursday February 24, 2011
Prof. Antonio Dobado
Universidad Complutense de Madrid, Spain

Abstract

According to Quantum Chromodynamics, which is the well established theory of strong interactions, quark and gluons are forced to live inside hadrons because of the property of confinement. However, under extreme conditions of temperature and pressure, a new phase called quark-gluon plasma is possible, where quarks and gluons became basically free. In the last years it has been possible to study this phase experimentally by using new facilities called Heavy Ion Colliders like the RHIC (Brookhaven) or the LHC (CERN).


Video
Thursday February 10, 2011
Dr. Christophe Morisset
Instituto de Astronomía, UNAM, Mexico

Abstract

We revisit the question of the ionization of the diffuse medium in late type galaxies, by studying NGC 891, the prototype of edge-on spiral galaxies. The most important challenge for the models considered so far was the observed increase of [O III]/Hβ, [O II]/Hβ and [N II]/Hα with increasing distance to the galactic plane. We propose a scenario based on the expected population of massive OB stars and hot low-mass evolved stars (HOLMES) in this galaxy to explain this observational fact. In the framework of this scenario we construct a finely meshed grid of photoionization models. For each value of the galactic latitude z we look for the models which simultaneously fit the observed values of the [O III]/Hβ, [O II]/Hβ and [N II]/Hα ratios. For each value of z we find a range of solutions which depends on the value of the oxygen abundance. The models which fit the observations indicate a systematic decrease of the electron density with increasing z. They become dominated by the HOLMES with increasing z only when restricting to solar oxygen abundance models, which argues that the metallicity above the galactic plane should be close to solar. They also indicate that N/O increases with increasing z.

Video
Tuesday December 14, 2010
Dr. Karsten Berger
Instituto de Astrofísica de Canarias, Spain

Abstract

This seminar talk will give a short overview of the current status of the field of Astroparticle Physics. The subject includes a great variety of instruments working in different energy ranges (from a few MeV to 1020 eV) and studying different particles (neutrinos, protons, gamma-rays and more). Finally, a short discussion regarding the connection between the observations and the physics at the Large Hadron Collider will be discussed.

Video
Thursday November 25, 2010
Prof. Frank Close
University of Oxford, UK

Abstract

Rutherford discovered the atomic nucleus in 1912 in an experiment on a table top. The LHC will be producing its first major results by 2012, involving teams of thousands and apparatus that is bigger than Rutherford's entire laboratory. How did science come to this, and what are the questions the LHC hopes to answer? What is Higgs' boson, and is it really Higgs that invented it? I will explore the role of symmetry and asymmetry in physics, and illustrate how the ideas that have been associated with Higgs' name have a long history.


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