Recent Talks

On March 17 the team responsible for the BICEP2 experiment, a CMB telescope located in the South Pole, announced the discovery of the primordial B-mode signal in the CMB polarization. This discovery inmediatly had a well-deserved impact in the media world-wide. In fact, it is the first observational confirmation of a prediction from the inflationary model, which was proposed at the beginning of the 80s as a solution for some inconsistencies of the Big Bang model. In this talk I will put this discovery in the context of CMB research, with a historical perspective. I will emphasize the importance of this discovery for Cosmology, and for Fundamental Physics, and will finally comment the prospects for the future, in particular the role of experiments like Quijote that have to confirm this signal.

R Coronae Borealis (RCB) stars are the more prominent group  of high luminosity hydrogen deficient stars that are rich in carbon  and helium. They also show characteristic irregular light drops of  several magnitudes (between 3 and 8 magnitudes) at unpredictable  times, caused by expulsion of self-made clouds of dust. They range in 
surface temperatures from 4500 K to  20000 K. Some of them seem to  have made even such complex molecules like fullerenes (C60) in their  circumstellar regions. Neither their evolutionary history nor the dust 
formation mechanism are well understood. Two scenarios that have been  suggested are that the present stars are a result of merger of two  white dwarfs (CO+He) or a post born-again (AGB) giant that is  surviving after a final helium shell flash. The talk would describe  the RCB properties and highlight the problems and challenges they pose 
in understanding their origins and dust production.

Because of the carbon dioxide emissions from fossil fuel burning, the Earth's atmosphere and oceans are warming through what is known as the "greenhouse effect". Big changes are on their way which we have not yet seen because of the time taken for the oceans to warm. It is essential that human communities prepare to adapt to these changes e.g. in sea level rise, severe heat waves, and a greater frequency of climate extremes.

The challenge to scientists is to learn enough about the complexities of the world's climate system to be able to project the climate's likely future.

The nations and peoples of the world need to recognise the urgency of the many actions that can - and must be taken.

Dwarf galaxies are a complex population. They comprise objects with young and old stellar populations, slow and fast rotation, as well as single- and multi-component structure. These characteristics show correlations with environmental density - we thus believe that dwarf galaxies hold a fossil record of how environment affected galaxy evolution. In this talk I will review and discuss recent progress on our understanding of dwarf galaxies in clusters, both from the observational and the modelling side. In particular, I will attempt to reconcile the proposed formation mechanisms of early-type dwarf galaxies - the most abundant population in clusters - with the continuous environmental influence predicted by cosmological simulations.

The theory of stellar evolution is well developed over the past decades, and in particular the predictions of one dimensional numerical models have passed basic observational tests. With the advent of high precision astronomical observations, these tests can now be improved to fine tune the physics of the models. In particular, the combination of exploiting binary properties with the information obtained from asteroseismology, proves to provide a promising test framework. However, both binarity and seismology increase the complexity of the observational models and their relation to the stellar evolutionary model, and therefore require as many independent tests as possible.

Majority of galaxies reside in groups and clusters where they are understood to evolve also through galaxy-galaxy interactions. Multiple mergers at the core of galaxy groups can develop a luminosity deficiency or gap, which is quantified as the difference between the luminosity of the two brightest galaxies in groups and clusters. This observable carries important information about the evolution of galaxy groups, for instance, there are indications that collapsed groups with a large luminosity gap, known as fossil groups, are associated with the halos that are relatively old. In a series of recent studies, employing X-ray, optical and radio observations complemented by cosmological simulations, we have utilised the luminosity gap to probe the formation scenarios for galaxies and specially the most luminous galaxies in groups and clusters, introduce a powerful age-date routine for galaxy groups, and also obtain clues about the AGN activities and the IGM heating.

The chromosphere is the interface between the photospheric solar surface and the outer corona and wind.  In this complex domain the
solar gas becomes transparent throughout the ultraviolet and in the strongest spectral lines while magnetic pressure becomes dominant over gas pressure even in weak-field regions.  Fine-scale magnetically caused or guided dynamic processes in the chromosphere constitute the roots of mass and energy loading of the corona and solar wind. Notwithstanding this pivotal role the chromosphere remained ill-understood after its basic NLTE radiation physics was formulated in the 1960s and 70s.  Presently, both chromospheric observation and
chromospheric simulation mature towards the required sophistication.  The open-field features seem of greater interest than the easier-to-see closed-field features. For the latter, the grail of coronal topology and eruption prediction comes in sight.

I will start with an introductory overview, show movies to present the state of art in observation and simulation, and treat some
recent success stories in more detail.

The IAC is the only Spanish Institution participating as a full member in SDSS-III (2009-2014). The survey finishes in June 2014, and will publicly release all data by the end of the year, including H-band high-resolution spectra for 100,000 stars in the Milky Way and optical mid-resolution spectra for 1.5 million LRGs and 160,000 quasars.

SDSS-IV will immediately follow, including spectroscopic surveys of variable sources, x-ray source follow-up observations, galaxy and quasar redshifts, Integral-field-unit spectroscopy of galaxies and high-resolution infrared spectroscopy of galactic stars, organized in the following projects: Time-Domain Spectroscopic Survey (TDSS), SPectroscopic IDentification of ERosita Sources (SPIDERS), Extended Baryon Oscillation Spectroscopic Survey (eBOSS), Mapping Nearby Galaxies at APO (MaNGA), and the APO Galaxy Evolution Experiment 2 (APOGEE-2).

The participation of the IAC in SDSS is gaining strength. As an example, in the first half of 2013, about 13% of the papers published by IAC researchers used SDSS data, and these papers contributed 33% of the citations received by the IAC in the same period. We will provide an overview of SDSS activities at the IAC, and current plans for participating in SDSS-IV (2014-2020).

1) López-Corredoira & Gutiérrez (2012, RAA, 12, 249): Extremely luminous QSOs exist at high redshift but they are absent at low redshift. Our analyses show that it is not due to any significant evolution of black hole masses or Eddington ratios for equal luminosity QSOs, so the problem can be translated into a "Why are not there QSOs with very high black hole masses at low redshift?". 2) López-Corredoira & Perucho (2012, A&A, 544, 56): The MOJAVE survey contains 101 quasars with a total of 354 observed radio components that are different from the radio cores, among which 95% move with apparent projected superluminal velocities with respect to the core, and 45% have projected velocities larger than 10c (with a maximum velocity 60c). Relativistic Doppler boosting explains these apparent anomalies, but it requires a huge average kinetic power to produce such powerful ejections: ~7×10^{47} erg/s, a significant portion of the Eddington luminosity and on the order of the bolometric luminosity. This amount is much higher than previous estimates of kinetic power on kpc-scales. 3) There are many other pending problems in QSOs in the literature (review at López-Corredoira 2011, IJAA, 1, 73): the different structure of the clouds along the QSO's line of sight and their tangential directions; the spatial correlation between QSOs and galaxies; inconsistencies in the AGN unification model; etc.

The accelerated expansion of the Universe discovered in the late 90's has opened one of the most intriguing questions of modern  physics. To help to understand its origin, and measure the expansion history of the Universe, large galaxy spectroscopic surveys are being carried out and planned for the future. In this talk, I will review the Baryon Oscillation Spectroscopic Survey (BOSS) and the requirements to achieve its precise results. I will then describe a sample of large-volume high-resolution N-body simulations available at MultiDark database,
that are useful to test the models. Finally, I will present some work I have been doing aimed at producing a large number of mock galaxy catalogs using an improved lagrangian perturbation theory calibrated with these simulations. Mock galaxy catalogs are essential to produce reliable cosmological constraints from these surveys.