Recent Talks

Although there is increasing speculation that the evolution of galaxy bulges may be regulated by AGN-induced outflows associated with the growth of the central supermassive black holes, the importance of AGN-induced outflows relative to those driven by starbursts has yet to be established observationally. In this context we have recently presented a study focusing on AGN-induced outflows in a sample of local Seyftert-ULIRGs. Perhaps, our most interesting result is related to the energy that the AGN returns to the galaxy in the form of feedback. We find that the typical mass outflows rates and kinetic powers of the emission line outflows are, in general, less energetically significant than the neutral and molecular outflows in ULIRGs and moreover, than those required today in the majority of the current hydrodynamic simulations that include AGN feedback. However, the uncertainties in the existing measurements are large, and more accurate estimates of the radii, densities and reddening of the outflows are required to put these results on a firmer footing. In this context, we are using HST /ACS+STIS and VLT-Xhsooter observations to accurately estimate sizes, electron densities and reddening to eventually provide the most accurate estimates of the kinetic powers associated with the ionized gas. In this talk I will describe in detail the results of this study focussing on testing the current simulations of hierarchical galaxy evolution.

How do the first galaxies form and evolve? Optical and near-infrared deep surveys are now finding galaxies at very high redshifts. However, they are typically small, not massive and present some but not very high star formation. But now the Herschel Multi-tiered Extragalactic Survey (HerMES), the largest project that has being carried out with the Herschel Space Observatory, in collaboration with other groups, has discovered a massive, maximum-starburst galaxy at a redshift of 6.34. The presence of galaxies like HFLS3 in the early Universe challenges current theories of galaxy fomation and evolution. I will describe the method we have developed to find these galaxies, the follow-up observations with different facilities and the main physical properties of this extreme object.

Taking advantage of the ultra-deep near-infrared imaging obtained with the Hubble Space Telescope on the Hubble Ultra Deep Field, we detect and explore for the first time the properties of the stellar haloes of two Milky Way-like galaxies at z~1. We find that the structural properties of those haloes (size and shape) are similar to the ones found in the local universe. However, these high-z stellar haloes are approximately three magnitudes brighter and exhibit bluer colours ((g-r)<0.3 mag) than their local counterparts. The stellar populations of z~1 stellar haloes are compatible with having ages <1 Gyr. This implies that the stars in those haloes were formed basically at 1<z<2. This result matches very well the theoretical predictions that locate most of the formation of the stellar haloes at those early epochs. A pure passive evolutionary scenario, where the stellar populations of our high-z haloes simply fade to match the stellar halo properties found in the local universe, is consistent with our data.

Total spectral irradiance is typically modeled by assinging an atmospheric model to each pixel of a full disk image and geometricllay combining the predicted wavelength dependent intensity for each of these models into a disk integrated spectrum. This works reasonably well, as the hydrostatic models that are used in this procedure generally reproduce observed spectra very well. However, for numerical expedience this scheme neglects some important physical aspects of the the solar atmosphere, in particular its three-dimensional and strongly dynamic nature. In this talk I will discuss the importance of some of these effects on the spectral irradiance signal, using forward radiative transfer modeling in realistic three-dimenional simulations. Obviously, modeling the three-dimensional dynamic structure over the whole disk is computaionally prohibitive, but if some of the effects discused above are important, strategies will have to be implemented to incorporate them approximately. Characterizing these cotributions to the spectral irradiance will also help us to better understand the physical nature of the forces that drive variability, and hopefully improve our predictive capabilities. 

X-ray observations performed by several missions during the last few decades have provided a very large data base on black hole X-ray binaries. Many of these objects are transient systems that spend most part of their lives in quiescence, showing occasional outburst where their luminosity increases up to eight orders of magnitude. I will review the state-of-the-art in the field, focussing on the different accretion regimes observed in these sources. In the second part of the talk I will concentrate on the influence that the orbital inclination (i.e., viewing angle) has in the spectral properties of black hole binaries, with emphasis on the detection of relativistic effects in the inner accretion flow surrounding the black hole.

On February 15, while we were preparing to observe the close approach of the potentially hazardous asteroid (PHA) 2012 DA14 another small asteroid entered the Earth’s atmosphere over Russia. The object, of about 17m in diameter and  11.000 tons exploded in the atmosphere generating a bright flash, a powerful shock wave and small fragmentary meteorites. About 1500 people were injured because of the shock wave effects in the city of Chelyabinsk located east of the Ural Mountains and on the border of Europe and Asia. The more than 400 kilotons released suggest that this was largest asteroid that entered the Earth atmosphere since the 1908 Tunguska event.

The differences between the orbits of DA14 and the asteroid that caused the Chelyabinsk event showed that both objects are not related. The composition of the meteorite and the spectrum of DA14 we obtained with the GTC also support that.

In this talk I will resume all the information about the Chelyabinsk event and discuss the relevance of studying the near-Earth asteroids, in particular the PHAs, and present the main results of our study of asteroid DA14 (de León et al. 2013). I will also discuss the relevance of space mission studies on this objects and resume our participation in MarcoPolo-R and AIDA missions. 

Evolution of galaxies is relatively well known up to z ~ 5, but beyond this limit and regarding the few number of galaxies confirmed by spectroscopy, their evolution is still uncertain. In the last five years, many projects and instruments aiming at pushing the limits of the Universe have emerged. Among them, the WIRCam Ultra Deep Survey (WUDS), a very large (~400 arcmin^2 field of view) and deep (m_H=27.00 AB) survey covering wavelength from Y to Ks bands, dedicated to select the brightest sources at z > 4.5, has just been finished.This survey takes benefit from the deep images from the CFHT-LS (Groth Strip) in u, g, r, i and z-band to improve the wavelength coverage and thus the determination of photometric redshift in each sample. The evolution of galaxies has been studied through the evolution of the UV Luminosity Function from z~5 up to z~9. During this talk I will present you the WIRCam Ultra Deep Survey and the most popular method used to select the very high-redshift sources. Then I will focus on the determination of the luminosity function and on the implications of this evolution on the Epoch of Reionization. I will finish this presentation by giving some perspectives, and especially the results that we can expected from futures instruments and telescopes (e.g. EMIR @ GTC, KMOS and MUSE @ VLT, JWST, E-ELT).

Segunda charla que ofrecemos a todo el personal del IAC para su 
posterior uso en charlas de divulgación. En este caso se trata de una 
charla para público adulto o jóvenes de secundaria o bachillerato.
Puede adaptarse fácilmente según audiencia. El material quedará
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Es una charla sencilla en la que lo que cuenta es lo que se cuenta...
Ven, sorpréndete (y cuéntalo!)

The CoRoT space mission aims at detecting planets with the transit method. In operation for more than 6 years, the instrument has monitored a couple of ten fields located in two opposite directions the Galactic plane for durations up to about 160 days. Transits are detected in about 100 up to 300 light curves per run. The large majority of them are however pinpointed as transiting stellar systems thanks to the identification of secondary eclipses or light curve modulation. The nature of the remaining candidates is then assessed through a multi-step strategy of complementary observations. This approach has allowed the discovery of a variety of planets with a large range of properties, from the first Super-Earth, CoRoT-7b to CoRoT-9b, the first temperate hot Jupiter or even the two transiting companions in the theoretical mass domain of brown dwarfs. We will review the status of the mission and then present the CoRoT exoplanetary systems and their properties.

The stellar spectroscopic sequence has now been extended into very cool objects bridging the gap between low-mass stars and classical planets. Those objects, called Y dwarfs, are the coolest substellar objects known to date with temperatures below 500 Kelvins. We obtained z-band far-red imaging for six Y dwarfs and a T9+Y0 binary with GTC/OSIRIS to characterise their spectral energy distribution. This photometric dataset represent the first optical detection of Y dwarfs. I will present the z-band photometry, optical-to-infrared colours, and proper motions of these Y dwarfs. I will discuss the larger dispersion in the optical-to-infrared colours of Y dwarfs than in warmer brown dwarfs, which may originate from presence of sulfide clouds, the depletion of alcalines, and/or gravity effects.