Recent Talks
List of all the talks in the archive, sorted by date.
Abstract
The properties of molecular clouds associated with 10 H II regions were studied using CO observations. We identified 142 dense clumps within our sample and measured and calculated physical properties of the clumps such as size, excitation temperature, line widths, density and mass. We found that our sources are divided into two categories: those that show a size-line width relation ("type I") and those which do not show any relation ("type II"). Type II sources have larger line widths in general. Investigating the relation between the line width and other parameters shows that while the MLTE (Local Thermodynamic Equilibrium mass) increases with ΔV (line width) for both 12CO(2-1) and 13CO(2-1) lines in type I sources, no relation was found for type II sources. No relation between column density and line width was found for either category. We also investigated how the characteristics of the clumps vary with distance from the HII region. We found no relation between mass distribution of the clumps and distance from the ionization front, but a weak decrease of the excitation temperature with increasing distance from the ionized gas. Only the projected distance is measured in our study which is equal or smaller than the true value. Therefore we compared the results by a Monte Carlo simulation of a central heating source and found that for small distances the relation is very scattered, which is consistent with our results. No relation was found between line width and distance from the H II region which probably indicates that the internal dynamics of the clumps is not affected by the ionized gas. Internal sources of turbulence, such as outflows and stellar winds from young proto-stars may have a more important role.
Abstract
A Friedman-like cosmological model, based on noncommutative geometry, is presented. Its Planck level is totally nonlocal with no space and no time. The dynamics on this level is strongly probabilistic which makes the initial singularity statistically insignificant. Space, time and the standard dynamics emerge when one goes from the non-commutative regime (on the Planck level) to the usual "commutative physics".
Abstract
Survey operations with the VISTA telescope with it wide field near IR camera started in Feb 2010, following a science verification phase that started in Oct, 2009. I will describe this new 4.2m wide field telescope and the ESO VISTA Public survey program. I will give details of all ESO six public surveys which will be used for a range of galactic and extragalactic science. I am the PI of the largest, by area, VISTA survey, I will focus my talk on the VISTA Hemisphere Survey and I will show how this survey will be used to find quasars in the Epoch of Reionization at redshift greater than 7. The VISTA Hemisphere Survey (VHS) has been been awarded 300 clear nights on the 4.2m ESO VISTA telescopes. VHS observations started i February, 2010 and the survey will take 5 years to complete. The VHS will cover the whole southern celestial hemisphere (dec<0) to a depth 4 magnitudes fainter than 2MASS/DENIS in at least two wavebands J and K. In the South Galactic Cap, 5000 square degrees will be imaged deeper, including H band, and will have supplemental deep multi-band grizY imaging data provided by the Dark Energy Survey (DES). The remainder of the high galactic latitude sky will be imaged in YJHK and combined with ugriz wavebands from the VST ATLAS, SDSS BOSS and Skymapper optical surveys. The medium term scientific goals include: a huge expansion in our knowledge of the lowest-mass and nearest stars; deciphering the merger history and genesis of our own Galaxy; measurement of large-scale structure out to z=1 and measuring the properties of Dark Energy; discovery of the first quasars with z > 7. In my talk, I will describe the scientific motivation and methodology of the search for quasars with z > 7.
Abstract
La Astronomía, quizá la ciencia organizada más antigua, presente en todas las culturas, que en este Siglo XXI es fundamentalmente Astrofísica, intenta penetrar en el conocimiento de la naturaleza y evolución del Universo, en su conjunto y en detalle. En tan desmesurada aventura, la clave para avanzar sigue siendo la observación astronómica. Y Canarias ha tenido la suerte de que la atmosfera de sus cumbres posea condiciones excepcionales para la observación astronómica. Por eso los observatorios del Instituto de Astrofísica de Canarias (IAC) reúnen la batería más completa de telescopios. Estos observatorios de Canarias constituyen una reserva astronómica mundial, protegida por ley, donde tienen telescopios e instrumentos más sesenta instituciones de dieciocho países. En el Observatorio del Roque de los Muchachos, además, acaba de entrar en operación el Gran Telescopio Canarias, construido por España. Siendo, con sus 10.4 m. de apertura, el mayor y más avanzado telescopio óptico-infrarrojo del momento. Pronto, esperamos, que a él también venga el Telescopio Europeo Extremadamente Grande (E-ELT) de 42 m., haciendo de en nuestras Islas el centro de gravedad de esta rama de la Ciencia.
La Astrofísica demanda la última tecnología para sus instrumentos en tierra y espacio. Por eso es germen de desarrollo tecnológico e industrial. Lo que supone riqueza económica y social. Sin dejar de ser por ello, como toda ciencia básica, fuente de cultura, al tratar de dar respuestas a las preguntas fundamentales del ser humano, y dotarle de nuevas cosmovisiones.
Abstract
The study of the Milky is expected to have a major impact on our understanding of how galaxies form and evolve. "Near-field cosmology" is being vigorously pursued through a series of major surveys of the Galaxy's stellar content (2-MASS, SDSS, RAVE, Hermes, Apogee, Gaia) that are either in hand or pending. It will be argued that what we want to know is deeply buried in these data and can only be extracted by comparing the surveys with a hierarchy of dynamical models of ever increasing complexity. Work currently being done to build such hierarchical models will be described, and some early results from this work will be summarised.
Abstract
There is a "Warped side" of our universe, consisting of objects and phenomena that are made solely or largely from warped spacetime. Examples are black holes, singularities (inside black holes and in the big bang), and cosmic strings. Numerical-relativity simulations are revolutionizing our understanding of what could exist on our universe's Warped Side; and gravitational-wave observations (LIGO, VIRGO, LISA, ...) will reveal what phenomena actually do exist on the Warped Side, and how they behave.
Abstract
Over the next decade or so, the gravitational-wave window onto the Universe will be opened in four frequency bands that span 22 orders of magnitude: The high-frequency band, 10 to 10,000 Hz (ground-based interferometers such as LIGO and VIRGO), the low-frequency band, 10-5 to 0.1 Hz (the space-based interferometer LISA), the very-low frequency band, 10-9 to 10-7 Hz (pulsar timing arrays), and the extremely-low-frequency band, 10-18 to 10-16 Hz (polarization of the cosmic microwave background). This lecture will describe these four bands, the detectors that are being developed to explore them, and what we are likely to learn about black holes, neutron stars, white dwarfs and early-universe exotica from these detectors' observations.
Abstract
Spectral energy distributions (SEDs) of the central few tens of parsec region of some of the nearest active galactic nuclei (AGN) are presented. Peering into the nucleus at these scales, it is found that the intrinsic shape of the spectral energy distribution of an AGN and inferred bolometric luminosity largely depart from those currently on use, mostly extracted from low resolution data. The shape of the SED is different and the AGN luminosities can be overestimated by up to two orders of magnitude if relying on IR satellite data.Although the shape of these SEDs are currently limited by the availability of high angular resolution data beyond ~20 μ, a prediction from this work is that a major contribution from cold dust below 100 K to these cores is not expected. Over the nine orders of magnitude in frequency covered by these SEDs, the power stored in the IR bump is by far the most energetic fraction of the total energy budget in these cores, accounting for more than 70% of the total.
Abstract
El curso tendrá un carácter eminentemente práctico. Tras una breve serie de presentaciones sobre el proyecto Observatorio Virtual y las herramientas de análisis existentes se procederá al desarrollo de casos científicos reales utilizando una metodología VO. El desarrollo de estos casos científicos se realizará bajo la supervisión de personal del Observatorio Virtual Español.
Abstract
El curso tendrá un carácter eminentemente práctico. Tras una breve serie de presentaciones sobre el proyecto Observatorio Virtual y las herramientas de análisis existentes se procederá al desarrollo de casos científicos reales utilizando una metodología VO. El desarrollo de estos casos científicos se realizará bajo la supervisión de personal del Observatorio Virtual Español.
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Recent Talks
