Recent Talks

In this talk I present an overview of the structure, activity and goals
of the Gaia-ESO survey, a large public spectroscopic survey aimed at investigating
the origin and formation history of our Galaxy by collecting high quality spectroscopy
of representative samples (about 105 Milky Way stars) of all Galactic stellar populations,
in the field and in clusters. Briefly, I discuss the most relevant results obtained so far.
In particular, I present our study on the internal kinematics of Galactic globular clusters based on the radial estimates obtained from the survey complemented with ESO archive data.

Can weather models be helpful for astronomers? In this talk, I do a revision of the state-of-the-art in numerical weather prediction models and its specific applications for astronomical observatories. In the context of flexible scheduling, the weather prediction models, and the mesoscale models in particular, can give a significant contribution in the management of the observing nights based on the forecasted atmospheric conditions. A prototype for the operational forecasting of the Precipitable Water Vapour above ORM for observations in the Infrared, currently under development, is presented and discussed.

Our group is presently conducting an observational campaign, using the 10-meter Gran Telescopio Canarias (GTC), to obtain the transmission spectrum of several exoplanets during a transit event. The GTC instrument OSIRIS is used in its long-slit spectroscopic mode, covering the spectral range of 520-1040 nm, and observations are taken using a set of custom-built slits of various, broad, widths. We integrate the stellar flux of both stars in different wavelength regions producing several light curves and fit transit models in order to obtain the star-to-planet radius ratio Rp/Rs across wavelength. A Markov Chain Monte Carlo (MCMC) Bayesian approach is used for the transit fitting. With our instrumental setup, OSIRIS has been able to reach precisions down to 250 ppm (WASP-48b, V=11.06 mag) for each color light curve 10 nm wide, in a single transit. Central transit timing accuracies have been measured down to 6 seconds.

Here, we will present refined planet parameters, the detection of planet color signatures, and the transmission spectrum of a set of know transiting exoplanets, namely: WASP-43b, HAT-P-32b, HAT-P-12b, WASP-48b. We will also discuss the capabilities and limitations of GTC with current and future instrumentation, and the role of GTC as tool for the follow up of faint Kepler targets. In particular, we will present the GTC observations of the intriguing evaporating planet KIC 12557548b, for which we performed simultaneous color light curves, and a search for alkali elements in its planetary tail. Other setups for observations (Broad and tunable filter photometry) have also been used and will be briefly discussed. The lessons learned from our GTC exoplanet observations will be discussed in the context of the E-ELT future capabilities.

Cognitive Astrophysics brings together tools, techniques and lessons learned from fields apparently as far apart as linguistics, philosophy and cognitive psychology, and merges them with modes and methods of understanding and discovery in modern cosmology, galaxy evolution and astrophysics. I will present an illustrated overview of the field from a variety of perspectives, and close with a discussion of "Pentessence" as an example of a globally organizing concept describing self-gravitating systems known to be operating on vastly different physical scales and in apparently disparate astrophysical circumstances.

At the end of 2013, the Hubble Space Telescope has started its last flagship program : the "Frontier Fields". In the framework of this project, three of the most powerful space telescopes to date - Hubble, Spitzer and Chandra - will dedicate a large amount of their observing time to observe six galaxies clusters, who act as additional lenses and amplify the light from background sources, including very faint galaxies to the edge of the observable Universe. These images will reach a depth comparable to the "Hubble Ultra Deep Field", but in a cluster field. Abell 2744, the first Frontier Fields target, has been observed by HST since November 1 and the first release has been made public on December 17. We have used this dataset to search for Lyman Break galaxy (LBG) at z>6.5 in the 4.9 arcmin^2 field of view of the WFC3. Several sources have been selected and the highest redshift object is estimated at z=8, called Abell2744_Y1. The amplification factor of this object is relatively modest (mu=1.5). We used our own reduced Spitzer images at 3.6 and 4.5 microns to constrain the Spectral Energy Distribution (SED) of the z=8 galaxy candidate. We computed its properties by SED-fitting using templates with and without nebular emissions. The star formation rate (SFR) in this galaxy ranges from 8 to 60Mo/yr, the stellar mass is in the order of (2.5-10) x 10^9 Mo and the size r=0.35+/-0.15 kpc, and it is consistent with expectations and previous estimates in this range of redshift. The brightness of this galaxy (F160W=26.2 AB) makes it one of the brightest z=8 object to date, and could be observed by current NIR-spectrograph in a reasonable amount of time.

Twenty years ago, no one convincingly knew the age or the size of the
Universe to within a factor of two. Ten years ago, everyone agreed on
those same two numbers to within 10%. Today, we arguably have brought
the errors down by another factor of two. But that has led to anxiety
rather than euphoria, renewed interest rather than complacency. The
problem is that there are now two independent, competing methods
giving answers of comparable precision and accuracy:
one is a model-based method using the cosmic microwave background
(the CMB), the other is a geometric, parallax-based method using local
measures of distances and expansion velocities. To within about
two-sigma the methods agree.  To within about two-sigma the methods
disagree. And basic physics (a fourth neutrino species, perhaps) hangs
in the balance.

I will discuss how this "tension" arose and how it will soon be
relieved.  A tie-breaker has been identified and developed, and it is
now being worked on from the ground and from space.

European Research Council (ERC) grants support individual researchers of any nationality and age who wish to pursue their frontier research. The ERC encourages in particular proposals that cross disciplinary boundaries, pioneering ideas that address new and emerging fields and applications that introduce unconventional, innovative approaches. ERC grants are awarded through open competition to projects headed by starting and established researchers - the sole criterion for selection is scientific excellence.

ERC grants are part of the European Horizon 2020 programme for research and innovation. Last December the ERC published the new work programme containing the first ERC calls under Horizon 2020. To gain an overall view of the rules and possibilities, we cordially invite you for an ERC information session.

Stellar-mass black holes have all been discovered through X-ray emission, which arises from the accretion of gas from their binary companions. Currently known black holes are fed by material stripped from a low-mass star or by the wind of a massive companion. Binary evolution models also predict the existence of black holes accreting from the equatorial envelope of rapidly spinning Be-type stars. However, among the ~80 Be X-ray binaries known in the Galaxy (~150 including the Magellanic Clouds), only pulsating neutron stars have been found as companions, which is known as the missing Be/black-hole X-ray binary problem. In this talk I present the first dynamical evidence for a 3.8-6.9 Msun black hole orbiting the Be star and gamma-ray candidate MWC 656 (=AGL J2241+4454). This discovery has been allowed by the detection of a HeII emission line from an accretion disc encircling the black hole. We find the black hole is X-ray quiescent with Lx<1.6 × 10−7 times the Eddington luminosity. This implies that Be binaries with black-hole companions are difficult to detect by conventional X-ray surveys and may be more abundant than predicted by population synthesis models.

Gaia - the ESA cornerstone astrometric mission - was launched in December 2013, with the goal of censing the Milky Way population in a 6D space (positions and velocity) of 10^9 point-like obects, with errors
100-1000 times smaller than Hipparcos, with three color magnitudes and spectra as well. The scientific impact of its data will be large in many fields of astrophysics, from Galactic science, to Solar system objects, to stellar astrophysics, to galaxies and Quasars; from the distance ladder revision to fundamental physics. I will describe the mission concept, the scientific goals, and the present status of the mission, with special attention to the flux calibration of Gaia data.