Recent Talks

Stars, the most fundamental building blocks of galaxies, are born within the clouds of gas and dust and and during their lives they enrich the gas and the interstellar medium (ISM) with heavy elements, magnetic fields, and cosmic rays all of which strongly affects the subsequent formation of stars and their host galaxy. To understand the evolution and appearance of galaxies it is therefore crucial to study the interplay between stars and the ISM. Putting together the infrared, submm, and radio observations of nearby galaxies, we have studied the physical properties of the dusty and magnetized ISM in nearby galaxies to address the pressing questions: How the ISM components are inter-connected and how their physical properties change in different galactic environments e.g. star forming regions, spiral arms, nucleus and outer disks? In what extent the star formation influences the physical properties and structure of the ISM in a galaxy? I will show the effect of star formation on the dust emission properties, interstellar magnetic fields, cosmic ray electron energy index and further discuss the important factors in the energy balance of the ISM at different scales in M33, M31, NGC6946, and other nearby galaxies.

The Sun is a magnetic star, not as magnetic as some stars, or as it was when it
was younger, but nonetheless magnetic fields dominate and even construct its
atmosphere. There would be no corona without magnetic fields. The surface is
also dappled with small scale magnetic field associated with surface convection
cells, granules and supergranules. But sometimes we also see much larger and
more powerful Active Regions containing sunspots. These are wounds in the
surface of the Sun that allow waves and oscillations in the solar interior and
atmosphere to be coupled much more directly than they usually are. In
particular, they allow the Sun's internal seismology (the p-modes) to drive a
variety of waves through the Active Region atmosphere, and conversely, the
atmospheres to pollute the internal seismology. This makes active region
helioseismology a very challenging field.

The importance of Luminous and Ultraluminous infrared galaxies (U/LIRGs) in the context of the cosmological evolution of the star-formation has been well established in the last decades. They have been detected in large numbers at high-z (z>1) in deep surveys with Spitzer and Herschel, and they seem to be the dominant component to the star formation rate (SFR) density of the Universe beyond z~2. Although rare locally, nearby U/LIRGs are valuable candidates to study extreme cases of compact star-formation and coeval AGN. In particular, the study of local U/LIRGs using near-IR integral field spectroscopic techniques allows us to disentangle the 2D distribution of the gas and the star-formation using high spatial resolution, and characterise dust-enshrouded, spatially-resolved star-forming regions with great amount of detail. In that context, we are carrying on a comprehensive 2D IFS near-IR survey of local 10 LIRGs and 12 ULIRGs, based on VLT-SINFONI observations. I will review different topics on the spatially resolved study of the ISM and the star-formation at different spatial scales. I will focus on the analysis of the multi-phase gas morphology and kinematics, and on the study of the spatially-resolved distribution of the extinction-corrected star-formation rate (SFR) and star-formation rate surface density (ΣSFR). In particular, I will present some recent results on the characterization of individual star-forming regions, in terms of their sizes and Paα luminosities.

The extragalactic background light (EBL) is the second most energetic diffuse background that fills our Universe. It is produced by star formation processes and supermassive black hole accretion over the history of the  Universe. Thus, it contains fundamental information about galaxy evolution and cosmology. Interestingly, it brings together classical astronomy and high energy astrophysics since gamma-rays from extragalactic sources such as blazars and gamma-ray bursts interact by pair-production with EBL photons. Therefore, it is also essential for extragalactic gamma-ray astronomy to understand precisely and accurately the EBL in order to interpret correctly high energy observations. In this talk, I will review the present EBL knowledge, and describe how we can extract information, such as the value of the expansion rate of the Universe, from the EBL. Finally, the latest all-sky Fermi-LAT catalog of hard sources (E>50 GeV), called 2FHL, and future directions of EBL research will also be discussed.

Gamma-ray astronomy is a new emerging and very successful branch of astrophysics. Exciting results have been obtained by the current generation Cherenkov telescope systems such as MAGIC, HESS and VERITAS. MAGIC is a ground-based detector, which consists of two 17 m diameter imaging atmospheric Cherenkov telescopes on the Observatorio Roque de los Muchachos on the Canary island of La Palma. The next generation Cherenkov Telescope Array (CTA) is currently in design. CTA is a large array of many telescopes of different sizes. Its construction will start beginning of 2016 with the construction of the prototype of the large 23m diamater Large Size Telescope (LST) on the island of La Palma, close to the MAGIC telescopes. In this presentation some beautiful results from MAGIC will be shown, as well as the current design of the LST and some key science physics related to the CTA and the LST.

The Virtual Observatory (VO) is an international astronomical community-based initiative. It aims at providing easy and efficient access and analysis of the information available at astronomical archives and services. The Spanish Virtual Observatory (SVO, http://svo.cab.inta-csic.es) is part of this initiative since 2004, coordinating the VO activities at national level. ARCHES (Astronomical Resource Cross-matching for High Energy Studies, http://www.arches-fp7.eu) is a FP7 project whose goal is to provide scientifically validated spectral energy distributions and cross-correlated catalogues of the sources included in the 3XMM (DR4) catalogue. These enhanced resources will definitively ease the exploration of a wide range of astrophysical questions by the time they become public (beginning 2016).

In this presentation, after an overall view of the current status of the Virtual Observatory and some of the most relevant VO-science projects carried out in the SVO framework, I will focus on the VO-science case I am responsible for within ARCHES: A multiwavelength study of circumstellar discs around late-type main sequence stars.

The immediate surroundings of our Milky Way galaxy are home to a number of dwarf galaxies, whose variety in shape, size, spatial location and velocity tells us that these Galactic satellites all have different tales to tell. While some look round, pristine and undisturbed, others have disturbed morphologies or show gradients in their metallicity, while yet others have unusual kinematic features or clearly show their dissolution into a stellar stream. Very few of them contain significant levels of gas, also prompting the question of what mechanism is responsible for stripping out their gas content. This talk will explore the eclectic mix of Milky Way dwarf galaxies and what their properties can reveal to us about their different stories, and also what they can collectively tell us of our own Galaxy. I will also discuss how looking at the Galactic vicinity is aiding us, via this population of Galactic satellites, in the increasingly popular area of near-field cosmology.

Little is known about the mid-infrared (MIR) polarization at high-angular resolution of Active Galactic Nuclei (AGN), however, the polarimetric mode of CanariCam on the 10.4-m Gran Telescopio CANARIAS has opened a new window to reveal its core. We have found a variety of results: 1) A Highly polarized synchrotron emission in the core of Cygnus A; 2) a very complex MIR polarization structures in and around the core of NGC 1068; and 3) a very low polarized core of Mrk 231. In this talk, I will present new CanariCam polarimetric results on several AGN which provide key information on our understanding of the AGN structure and jet formation.

MASTER-Kislovodsk auto-detection system discovered a faint transient in the Andromeda galaxy on January 13th 2015. It was originally identified as a classical nova and received designation M31N 2015-01a. Further observations showed discrepancies with the spectra and lightcurves typical for the classical novae. The transient was re-identified as a likely stellar merger (aka Luminous Red Nova (LRN)), similar to V838Mon. In this presentation I will deliver a short overview of our current understanding of this class of objects and a summary of the current state of the ongoing observing campaign of the M31 LRN. Recent results will be discussed with a particular emphasis on the contributions made possible by GTC and other observing facilities at Observatorio Roque de los Muchachos. At the final part of the presentation I will touch on follow up observations once M31 is available for observations again.

 I will present a multiwavelength study of a large MIPS selected galaxies and satisfy a certain IRAC color criterion. Stellar population modeling and IRS spectra together demonstrate that the double criteria used to select this sample have efficiently isolated massive star-forming galaxies at /z/ ~ 1.9. This is the first starburst (SB)-dominated ultraluminous infrared galaxies (ULIRG) sample at high redshift with total infrared luminosity measured directly from Spitzer, Herschel FIR and millimeter photometry, and as such gives us the first accurate view of broadband spectral energy distributions for SB galaxies at extremely high luminosity and at all wavelengths. The HST images in optical and NIR bands show that most objects have very extended morphologies in the rest-frame ultraviolet and optical band, thus extended distribution of PAH molecules. We conclude that objects in this sample are ULIRGs powered mainly by SB; and the total infrared luminosity density contributed by this type of objects at /z/ ~ 1.9.