Recent Talks

1- The use and abuse of N-body codes

- relaxation in spheres and disks,  collective enhancement

- code structure, block time steps

It is now clear that supermassive black holes (M>1e6 Msun) live in the center of most (all) galaxies, including our own Milky Way. Furthermore, the energy released during the growth of this black hole is a critical ingredient in understanding galaxy formation and evolution. In this talk, I will show what we know about how, when and where these supermassive black holes are acquiring their masses. In particular, I will focus on the effects of obscuration, as it is now clear that the majority of this black hole growth is hidden from our view by large amounts of gas and dust. I will present statistical evidence suggesting that while most nuclear activity is triggered by internal secular processes, the most violent episodes are linked to major galaxy mergers. Finally, I will show how future data obtained combining observations with the ALMA radio telescope and the NuSTAR X-ray observatory will allow us to understand the physical details of the connection between black hole growth and galaxy evolution.

In the past few years, a series of discoveries have been made of objects which appear to be accreting stellar mass black holes in globular clusters -- both in the Milky Way and in other nearby galaxies. I will discuss why the theoretical work which suggested that such objects would be unlikely to exist, the observations showing they do exist, some of the unusual aspects of some of the individual sources, and the new theoretical framework for producing them.

I will present the last results of the Transit Monitoring in the South (TraMoS) project. Since 2008, TraMoS has monitored transits of 30 exoplanets with telescopes located in Chile with the following goals: (1) to refine the physical and/or orbital parameters of those exoplanet systems, and (2) to search for Transit Timing Variations (TTVs) and perturbations in other transit parameters, that could indicate the presence of additional bodies in the system.   I will also discuss recent results and the scope of ongoing/future exoplanets projects at the IAC, in particular: transmission spectroscopy of selected exoplanets, secondary eclipse observations and dynamical simulations to validate/confirm exoplanets candidates.

The discovery of new planets beyond our solar system, in particular the detection and characterization of other habitable planets similar to the Earth, is a fascinating intellectual adventure. The completely unexpected characteristics of exoplanets are capturing the imagination and interest of the scientific community and the general public. More recently the large population of Super-Earth planet questions the universality of our Solar System as a typical planetary system. While the quest to find bodies similar to the Earth is still on going, the first spectra of exoplanets have been taken, signaling the shift from an era of discovery to one of physical and chemical characterization. This talk will provide an overview of current outcomes of planet programs as well as its limitation and prospects to move forward.

Gamma-Ray Bursts (GRBs) are the most powerful sources of electromagnetic radiation in the Universe. There are many open questions about their origin and their nature, and the answers should be searched in the large amount of data collected during these last years. We focused on the study of the their X-ray and optical afterglow properties, as observed by the Swift X-Ray Telescope (XRT) and ground-based optical telescopes. We investigated the observer and rest-frame properties of all GRBs observed by Swift between December 2004 and December 2010 with spectroscopic redshift through a comprehensive statistical analysis of the XRT light-curves of GRBs carried out in a model-independent way. We found out a three parameter correlation that is followed both by short and long GRBs. We also carried out a systematic analysis of the optical data available in literature for the same GRBs to investigate the GRB emission mechanisms and to study their environment properties. Our analysis shows that the gas-to-dust ratios of GRBs are larger than the values calculated for the Milky Way, the Large Magellanic Cloud, and the Small Magellanic Cloud. In this talk I will show the major results of the analysis of this large set of data.

 CanariCam is a mid-IR imager and spectrograph with polarimetric and coronographic capabilities built by the University of Florida as a common-user instrument for the GTC. CanariCam observing capabilities are unique, offering the GTC community the opportunity to exploit the 8-25 microns observing windows at the diffraction limit of the GTC. Grantecan started CanariCam operations during the first semester of 2012. Currently, three observing modes are offered to the GTC community: Imaging, low resolution spectroscopy and imaging polarimetry. In this talk, some of the challenges of operating a mid-IR diffraction-limited instrument from the ground will be reviewed. Some CanariCam commissioning results for the currently offered modes will be presented. I will introduce some of the tools available for the community to prepare CanariCam observations and to reduce the data. Finally, I will explain what is the current status of the instrument and telescope for mid-IR observations.

The life cycle of baryonic matter in a galaxy is driven by the exchange of material between the interstellar medium (ISM) and stars, which are the agents of galaxy evolution. Dust is present at these key transition phases of matter: in the ISM, in the circumstellar environments of newly forming stars and in stellar ejecta of dying stars. The Spitzer and Herschel wavelengths provide a sensitive probe of circumstellar and interstellar dust and hence, allows us to study the physical processes of the ISM, the formation of new stars and the injection of mass by evolved stars and their relationships on a galaxy-wide scale. Due to their proximity, well constrained viewing angle, multi-wavelength information, and measured tidal interactions with the Milky Way (MW), the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) are uniquely suited for surveying the agents of galaxy evolution (SAGE), the ISM and stars. In this talk, I will present some key results from the Spitzer SAGE and Herschel HERITAGE surveys including measurements of ISM mass estimates from dust emission, discoveries of thousands of young stellar object candidates, and precise measurements of dust mass loss rates from entire populations of evolved stars and w the mass budgets of these galaxies. I will end with a brief forward look to the future prospects with the James Webb Space Telescope Mission.

Crucial issues in cosmology and astrophysics are to understand the
process of galaxy formation and evolution and the nature of what
appears to be the dominant form of matter in the Universe, i.e. dark
matter. Dwarf galaxies provide important information on both of these
issues. In this talk, I will focus on the dwarf galaxies found in the
Local Group, as it is the galaxy population that can be studied in
the greatest detail than any other from the properties of their
resolved stellar populations. I will show how wide-area surveys have
led to a leap forward in our observational understanding of these
galaxies and discuss future prospects.

AzTEC is a sensitive bolometer camera that, coupled with 10-15m-class sub-mm telescopes, has mapped more than 3 sq. deg of the extragalactic sky to depths between 0.7 and 1.1 mJy at 1.1mm, prior to its current installation and operation on the 32m Large Millimeter Telescope (LMT). These extragalactic surveys targeted towards blank-fields and biased high-z environments alike have allowed us to identify regions of the sky where submillimeter galaxies (SMGs), powerful obscured starbursts at high-redshifts (z>1), cluster, and possibly mark the potential wells of accelerated galaxy-formation that will eventually form massive clusters. In this talk I will describe the evidence we have found for these overdense regions of massive galaxies, their structure and possible interpretation, as well as the follow-up observations we are carrying out with the LMT nowadays.