Recent Talks

I will review some recent results about the molecular content of galaxies and its dynamics, obtained from CO lines, dense tracers (HCN,HCO+), or the dust continuum emission. New data to constrain the conversion factor XCO will be discussed. The molecular surface density is essential to determine the star formation efficiency in galaxies, and the resolved Kennicutt-Schmidt law will be presented as a function of surface density and galaxy type. Large progress has been made on galaxy at moderate and high redshifts, allowing to interprete the star formation history and star formation efficiency as a function of gas content, or galaxy evolution. In massive galaxies, the gas fraction was higher in the past, and galaxy disks were more unstable and more turbulent. ALMA observations will allow the study of more normal galaxies at high z with higher spatial resolution and sensitivity.

One of the main contributions that archaeoastronomy —assisted by rigorous methodology— can bring to studies of religious practice, particularly in Greece, is to reintegrate the visible landscape and sky with ancient religious ritual. This paper is an introduction to the approach we can use in order to better understand the role of astronomical observations in the timing of ancient Greek religious festivals and cult. The paper demonstrates that, in the case of Greece, general conclusions on the predominant eastern orientation of Greek temples do not help us improve our narrative about the role of astronomy in Greek religious practice. The Greek religious system was complex, being influenced by local traditions, identity and myths. Therefore, by combining archaeology, ancient history and classics we are able to integrate the archaeoastronomical data in the context of specific cults and thus to better understand the religious experience of the people who attended and participated in these cults.

I am going to present the new massive and obscured cluster Masgomas-1. This cluster, discovered by our group formed by astronomers from the IAC and CEFCA, is the
first candidate derived from the preliminary version of our systematic search algorithm for obscured (and young) massive clusters, and part of the MASGOMAS project  (MAssive Stars in Galactic Obscured MAssive clusterS). In this talk I will present the spectrophotometric observations obtained with LIRIS at William Herschel Telescope (ORM), which allowed the physical characterization of the massive stellar population of Masgomas-1, and the confirmation of the  cluster's massive nature
(i.e. Mcl > 10^4 Msun).

Measuring distances to galaxies and determining their chemical compositions are two fundamental activities in modern extragalactic astronomy, in that they help characterizing the physical properties of their constituents and their evolutionary status. Ultimately, these measurements lead to stronger constraints on the cosmological parameters of an expanding universe and the history of cosmic chemical enrichment. Both these questions can be tackled afresh with the quantitative analysis of the absorption line spectra of individual massive and luminous, young B- and A-type supergiant stars. A spectroscopic distance determination method, the FGLR, can yield accurate distances up to several Mpc, extending to a local volume where the results can be compared with those obtained from Cepheids and other distance indicators. Moreover, and this being a unique advantage of the FGLR, reddening values and metallicities are simultaneously determined for each individual stellar target. These stellar metallicities are very accurate and can be used to constrain the formation and evolution of galaxies and to assess and overcome the systematic uncertainties of H II region strong-line abundances through a galaxy-by-galaxy comparison. Moreover, stellar spectroscopy provides fundamental complementary abundance information for star forming galaxies on additional atomic species such as iron-group elements. I will present recent results of our on-going efforts to study individual blue supergiant stars in galaxies within and beyond the Local Group based on medium and low resolution optical spectra collected with ESO VLT and the Keck telescopes. The promising perspectives of future work, based on the giant ground-based telescopes of the next generation (E-ELT, TMT) are also discussed.

I will review what we know about Type I Bursts (thermonuclear explosions on the surface of accreting Neutron Stars) and burst oscillations (fluctuations in the intensity of the burst lightcurves). I will describe the known problems in burst oscillation models and the various solutions that have been proposed. I will report recent progress made in the case of the pulsar IGR J17480-2446 in the Globular Cluster Terzan 5, where we were able to pin point the most likely mechanism responsible for the oscillations. I will explain whether this might be applicable to the other bursters and discuss future perspectives including current efforts to develop magneto-hydrodynamical simulations of the bursting process.

I will address the effects of bar-driven secular evolution in discs by comparing their properties in a sample of nearly 700 barred and unbarred massive galaxies. Through detailed structural decompositions I will show that, as a population, barred discs tend to have fainter central surface brightness and larger disc scale lengths than those of unbarred galaxies. Bars rarely occur in high-surface brightness discs and tend to reside in moderately blue discs. These results show that bars induce noticeable evolution in the structural properties of galaxy discs, in qualitative agreement with longstanding theoretical expectations.

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.