Recent Talks

Charla divulgativa sobre cultura preventiva en el IAC

The Square Kilometre Array (SKA) will be the world’s largest and most sensitive radio telescope. It will address fundamental unanswered questions about our Universe including how the first stars and galaxies formed after the big bang, how dark energy is accelerating the expansion of the Universe, the role of magnetism in the cosmos, the nature of gravity, and the search for life beyond Earth. This project envisages the construction of 133 15-m antennas in South Africa and 131,072 log-periodic antennas in Australia, together with the associated infrastructure in the two desert sites. In addition, the SKA is an exemplar Big Data project, with data rates of around 10 Tbps being transported out of the telescope to HPC facilities; and very exacting data processing requirements that are likely to need a combination of CPU, GPU and FPGA technologies to solve.

I will present ALMA Compact Array (ACA) 870 micron data of 28 infrared-bright SDSS quasars at redshifts 2 – 4 with estimated star formation rates beyond 1000 solar masses per year, the largest such sample ever observed with ALMA. The majority of the sources have unique ACA counterparts down to 3" - 4"resolution within the SPIRE 250 micron beam, centred on the SDSS coordinates. With only a handful of clear cases of multiple sources within the SPIRE beam, these results are in tension with works on the multiplicity of SPIRE 250 micron sources and sub-millimetre galaxies. I will present an extensive comparison between these findings and other recent works and will discuss the implications in the scenario supporting major mergers as triggers of the brightest AGN.

Binarity and mass transfer appear to play a key role in the shaping and, most likely, in the formation of planetary nebulae (PNe), thereby explaining the large fraction of axisymmetric morphologies. I present the binary hypothesis for PNe and its current status. Recent discoveries have led to a dramatic increase in the number of post-common envelope binary central stars of PNe, thereby allowing us to envisage statistical studies. Moreover, these binary systems let us study in detail the mass transfer episodes before and after the common envelope, and I present the evidences for mass transfer - and accretion - prior to the common envelope phase.

Charla divulgativa sobre cultura preventiva en el IAC

We present a detailed study of the spatially resolved thermodynamic and hydrostatic mass profiles of the five most massive clusters detected at z~1 via the Sunyaev-Zel'dovich effect. These objects represent an ideal laboratory to test our models in a mass regime where structure formation is driven mainly by gravity. We present a method to study these objects that optimally exploits information from XMM-Newton and Chandra observations. The combination of Chandra’s excellent spatial resolution and XMM-Newton’s photon collecting power allows us to spatially resolve the profiles from the core to the outskirts, for the first time in such objects.  Evolution properties are investigated by comparison with the REXCESS  local galaxy cluster sample. Finally, we discuss the current limitations of this method in the context of  joint analysis of future Chandra and XMM large programs and, more generally, of  multi-wavelength efforts to study high redshift objects.

I will discuss our present knowledge of the statistics of stellar multiplicity (the multiplicity fraction and the distribution of periods, mass ratios, and eccentricities), and the implications for stellar evolution, in particular for Type Ia Supernovae (SN Ia). I will describe how multi-epoch radial velocity measurements from large spectroscopic surveys can open a new observational window on stellar multiplicity, and present two case studies: white dwarfs in SDSS/SEGUE and the ESO SPY survey, and main sequence stars and red giants in SDSS/APOGEE. For the white dwarfs, we can measure their merger rate and evaluate their viability as Type Ia SN progenitors. For the main sequence stars and red giants, we can explore the interplay between stellar evolution and stellar multiplicity, evaluate the rate of stellar mergers, and uncover a strong dependence of the multiplicity fraction with metallicity.

The IAC Solar System group has been cooperating with NASA’s OSIRIS-REx mission since 2011 when I became member of its Science Team. In 2015 we came to an agreement to be members of the Image Processing Working Group (IPWG) to perform two main tasks: produce and analyze the Color-ratio Maps and participate in the in-flight calibration of the cameras (OCAMS). Actually 5 members of our group are participating in the science of the mission.

OSIRIS-REx was launched in 2016 and will visit the asteroid Bennu. It will completely characterize Bennu during 2018-2019, and took a sample of material from the surface that will bring to Earth for detailed study in 2023. Bennu is the primitive near-Earth asteroid more accessible and is also one of the Potentially Hazardous asteroids most likely to collide with Earth. It is well stablished that primitive class asteroids are the parents of carbonaceous chondrite meteorites, the meteorites with the most primitive known composition. Their primitive nature and their water and complex organics content make their study have a high cosmogonic and astrobiological interest

With the aim of supporting the science return of OSIRIS-REx and other two missions (JAXA’s Hayabusa II and ESA’s MarcoPolo-R), we started in 2010 our PRIMitive Asteroids Spectroscopic Survey (PRIMASS). As part of the PRIMASS project, we are obtaining visible and near infrared spectra of the members of the primitive collisional families and dynamical groups of the main asteroid belt. 

In this seminar I will present OSIRIS-REx mission and summarize the research activities of the IAC Solar System group, in particular those related with our participation in the OSIRIS-REx mission: (1) the preparation for the analysis of OCAMS images using Dawn images of Ceres; (2) the spectroscopic characterization of the inner main belt primitive asteroids families from which Bennu likely came from.

The discovery of relic galaxies in our nearby Universe allow us to explore the physical conditions that took place at the early stages of galaxy formation (z>2) with unprecedented detail. In this talk, we will describe how these objects have been found, what is the physical motivation to explore them and what are the most relevant results we have learnt so far. In particular, in this seminar, we will focus on our recent publication in the journal Nature, where we study the globular cluster population of the massive compact relic galaxy NGC1277 using the Hubble Space Telescope. The analysis of its globular cluster population has confirmed the extraordinary nature of this object. This galaxy underwent  an early collapse phase but failed to evolve and accrete smaller satellite galaxies. The study of the globular cluster of this system (which has no similar counterpart in the near Universe) gives unique insights into the formation and evolutionary processes of the most massive galaxies.

The kinematic characterization of different galaxy populations is a key
observational input to distinguish between different galaxy evolutionary
scenarios, since it helps to determine the number ratio of rotating disks
to mergers at different cosmic epochs. Local luminous and ultra-luminous
infrared galaxies [(U)LIRGs] offer a unique opportunity to study at high
linear resolution and S/N extreme star forming events and compare them
with those observed at high z.
We obtained Very Large Telescope (VLT) VIMOS optical integral field
spectroscopy (IFS) data of a sample of 38 local (z < 0.1) (U)LIRGs (50
individual objects). Our goal is to analyze in detail the kinematics of
the
H\alpha ionized gas applying kinematic criteria able to characterize the
evolutionary status of these systems. In particular, the unweighted and
weighted kinemetry-based methods are used to kinematically classify our
galaxies in disk and merger. We also simulate our systems at z=3 to
evaluate how a loss of angular resolution affects our results.
From the kinemetry-based analysis we are able classify our local (U)LIRGs
in three distinct kinematic groups according to their total kinematic
asymmetry values (Ktot) as derived when using the weighted (unweighted)
method: 1) 25 out of 50 galaxies are kinematically classified as disk; 2)
9 out of 50 galaxies are kinematically classified as merger; 3) 16 out of 50
galaxies lie in the transition region, in which disks and mergers coexist.
When we apply our criteria to the high-z simulated systems, a lower total
kinematic asymmetry frontier value is derived with respect to that found
locally. The loss of angular resolution smears out the kinematic features,
thus making objects to appear more kinematically regular than actually they
are.