Recent Talks

Low-luminosity AGN (LLAGN; LINERs and low-luminosity Seyferts) are present in numerous nearby galaxies and are often suggested to be the "missing link" between bright AGN and "normal", quiescent systems. Their accretion physics appear to differ from those of higher-luminosity AGN, and their place in the AGN unified scheme is not yet clear. Mid-IR observations promise new constraints on the accretion mechanisms and obscuring medium in LLAGN. However, their mid-IR emission remains almost completely unexplored at the high angular resolution needed to separate the weak nucleus from the host galaxy. I will show the results of an exploratory imaging study of ~20 LLAGN using Michelle and T-ReCS on the Gemini telescopes. Combined with Spitzer spectroscopy and high-resolution multi-wavelength information, the data establish, for the first time, the general nuclear IR properties of these objects. There are some hints that the obscuring torus disappears at low AGN luminosities, and we are also able to provide "dust-free" candidates for detailed study of the disk and jets.

Solar Orbiter is the first mission of the ESA Cosmic Vision program and that has recently been approved at implementation level. It is an M class mission with a predicted launch in 2017. Solar Orbiter will approach the Sun to a distance of 0.28 AU and perform coordinated in-situ and remote sensing observations of the Heliosphere and the Sun. It's main scientific goal is to understand the link between physical processes at the solar surface and their impact in the inner Heliosphere. A series of gravity assist manoeuvres with Venus will kick the mission out of the ecliptic plane until it reaches an angle of 35 degrees. From this vantage point, we will observe for the first time the Solar Poles without suffering from strong projection effects. These observations can help us understand key physical ingredients of the solar dynamos such as the meridional flow and the polar field reversal. Solar Orbiter includes ESA and NASA participation and it is the first time a space mission has two instruments where Spain participates at PI level. In particular IAC/INTA is co-PI of the Polarimetric and Helioseismic Imager, a magnetograph to image the solar surface magnetic field.

Supermassive black holes are ubiquitous in galaxies and play a fundamental role in their life cycle. I will review observational progress in defining and refining the various empirical scaling relations between black hole masses and host galaxy properties. I will emphasize ways in which the intrinsic scatter of the scaling relations can be quantified, and present evidence that the scatter correlates with physical properties. I will describe how the scaling relations can be extended to active galaxies and summarize preliminary efforts to probe the evolution of these scaling relations with redshift. I will present new measurements of the cold ISM content in AGN host galaxies and constraints they place on currently popular models of AGN feedback. Lastly, I will discuss a new class of low-mass black holes in bulgeless and dwarf galaxies that serve as local analogs of seed supermassive black holes.

Golden Age of Astronomy” does not only influence professional but also amateur astronomy. Today, amateurs basically use the same technologies as the professionals. This includes the most important tool – spectroscopy. There is an important gap in professional astronomical spectroscopy which can be filled by amateurs and their smaller telescopes. Some stellar phenomena need longer time coverage, of order, e.g., some weeks. This is especially valid for binary stars. One such interesting target is Wolf-Rayet 140, a WR+O binary with a highly eccentric orbit and a period of about 8 years. The observation of its periastron passage in the visible wavelength range is valuable for measurements in other wavelength domains to understand the wind-wind shock interaction of both components and the global geometry and physics of the system. For this and some other massive star targets, a group of amateur and professional astronomers performed a successful campaign for 116 nights at the 50 cm Mons telescope at Teide observatory, supported by the IAC and embedded in a joint worldwide X-ray, visual and IR campaign. The group of observers was a mix of enthusiastic astronomers from various professions (e.g., physicists, a physics student, a chemist, a physician, a schoolboy, a pilot) but they all have been experienced and enthusiastic observers. The talk will highlight the most important results of this campaign

Abstract: The study of the structure of our Galaxy, particularly its inner disc, has always been hindered by two factors: interstellar extinction dims even the brightest stars at optical wavelengths and the high source density prevents us, as the proverbial trees, to see the big galactic picture. 

Stellar halos of galaxies offer an important laboratory to understand the galaxies’ formation process and evolution. In fact, the dynamic time scale in the halos are large, and the imprint of the formation mechanisms may still be preserved at large radii in the kinematics, in the orbital structure, in streams and substructures, or in the chemical composition and distribution of stars.

I will discuss i) the kinematic and dynamical properties of stellar halos in early type galaxies as derived from tracers like planetary nebulae and globular clusters; and ii) the stellar population properties as derived from deep long-slit spectra in a number of massive ellipticals. Results are then discussed in the framework of galaxy halo formation mechanisms.

With the advent of GPU accelerators the landscape of High Performance Computing has started to change rapidly. While this is in principle good news, the increased compute power comes with a steep price tag in that new languages (CUDA, OpenCL) must be used. Recently Intel has announced their own coprocessor Many Integrated Cores (MIC) technology which will deliver competitive performance but will be programmed through familiar languages (Fortran, C/C++ and OpenMP). In my talk I will introduce Intel's MIC architecture and will discuss the ongoing efforts at the Texas Advanced Computing Center to build a 10 PetaFlop cluster with MIC coprocessors in early 2013. Coprocessors (MIC) and accelerators (GPU) are here to stay and the changing hardware will spur considerable changes in general software design. Astrophysics codes of all varieties (for example highly parallel simulations, data-intensive software pipelines for large surveys, and even data reduction software on desktops) will have to adapt to the new environment. I will discuss software design, performance considerations, and optimizations in general and specifically with respect to the MIC technology. In the second part of my talk I will introduce the software package ASSET (Advanced Spectral Synthesis 3D Tool) that allows for the fast and efficient calculation of spectra from 3D hydrodynamical models and will highlight recent projects that have employed high-resolution (> 1,000,000), wide-range (1000's of Angstroem) synthetic spectra derived from 3D radiation transfer.

Solar magnetism may look deceptively boring (a rather common star with relatively low activity). As it turns out, even the most quiet areas of the Sun (away from the sunspots) harbour a rich and interesting magnetic activity which is extremely complex and dynamic at spatial scales as small as ~100 km. And more importantly, this magnetism permeates most of the Sun, all the time. Therefore, it is not surprising that it might play an important role for solving some longstanding questions of stellar magnetism as: how is the million degree corona maintained when all sunspots have disappeared during the minimum of magnetic activity? And this is of interest not only for solar physics but for stellar astrophysics too, since it is expected that every star with a convective envelope harbours small-scale magnetic activity that we cannot hope to observe with the great detail we observe it in the Sun. From the first evidence of the presence of magnetic fields in the quiet areas of the Sun to the discovery of the smallest organised magnetic structures ever observed in a stellar surface just 30 years have passed. In this seminar, I will give an overview of our present knowledge about the small-scale quiet Sun magnetism. In particular, I will show how small loops of sizes of several hundreds of kilometers appear in the surface and travel across the solar atmosphere, reaching upper layers and having direct implications on chromospheric (coronal) magnetism. I will also show some of the properties of these newly discovered magnetic structures such as their spatial distribution, a key ingredient for understanding their origin.

The mechanism by which AGN activity is triggered has long been debated. One, often suggested, method of doing so is major, gas-rich mergers and galaxy interactions. I will present deep Gemini GMOS-S images of a sample of type II quasar host galaxies, demonstrating that 75% show clear signs that they are undergoing some kind of interaction. We compare these results with a control sample of quiescent early-type galaxies and find a similar rate of interaction (68%). However, we also find that the surface brightness of the features of the type II quasars are up to 2 mags brighter than those for the control sample, suggesting a difference in the types of mergers that the two groups are undergoing. We also compare our results with those for a sample of powerful radio galaxies and find very similar values for the surface brightness of the detected features.

The status of instrumentation at GTC and other ORM/OT telescopes will be reviewed. A short introduction regarding the different ways to access telescope time (normal call for proposals, service nights and DDT) will also be given. The aim of this talk is to help preparing observing proposals for the coming semester 12B.