Recent Talks

The expansion rate of the Universe parameterized by the Hubble-Lemaître parameter H(z), has been a major endeavor in cosmology since the discovery of the expanding Universe. In the last years, significant effort has been put forth to measure with high precision the local value of the Hubble-Lemaître parameter known as the Hubble constant (H0), and today H0 is estimated from the distance ladder with an uncertainty of <3% . Perplexingly, these findings have revealed a dramatic discrepancy dubbed "the Hubble tension": the estimation of H0 from the local distance ladder is in strong disagreement (at 4.4σ or 99.99% level) with the value inferred at high-redshift from the angular scale of fluctuations in the cosmic microwave background (CMB), possibly hinting towards new physics beyond the standard model. This discrepancy represents the most urgent puzzle of modern cosmology, and it is nowadays one of its hottest topics. The HOSTFLOWS project aims to advance towards solving of this tension by (i) performing an unprecedented study of the local environments of nearby standard candles to address the leading systematic uncertainties in the measurement of H0, and (ii) reconstructing the panorama of our supercluster Laniakea by studying cosmic flows using type Ia supernovae (SNe Ia) in the near-infrared (NIR). In this talk, I will introduce the topic and summarize the current and future efforts HOTFLOWS is doing in this regard.

Zoom link: https://rediris.zoom.us/j/81863823691?pwd=OFM1QW9Qc0dOQjZZVVd5RHAxM3FvQT09

Meeting ID: 818 6382 3691

Passcode: 223140

Youtube link: https://youtu.be/uGQPTJCZIfE

Did you ever want to re-run your project from the beginning, but run into trouble because you forgot one step? Do you want to run just one part of your project and ignore the rest? Do you want to run it in parallel with many different inputs using all the cores of your computer? Do you want to design a modular project, with re-usable parts, avoiding long files hard to debug?

Make is a well-tested solution to all these problems. It is independent of the programming language you use. Instead of having a long code hard to debug, you can connect its components making a chain. Make will allow you to automate your project and retain control of how its parts are integrated. This SMACK seminar will give an overview of this powerful tool.

Gitlab link: https://gitlab.com/makhlaghi/smack-talks-iac/-/tree/master/

EST es un proyecto para construir un telescopio solar de clase cuatro metros dedicado a la observación del sol con alta resolución y alta precisión polarimétrica desde los Observatorios de Canarias. Con él se pretende aunar y mejorar las prestaciones de los telescopios de clase un metro que están operativos en la actualidad. En esta charla, veremos las diferentes fases por las que ha ido pasando el proyecto, su situación actual y las perspectivas de futuro.

https://youtu.be/lnLKdvQWpE0

Following Cowling's anti-dynamo theorem of 1933, there was a long period during which the very existence of dynamos was unclear. Even with the emergence of three dimensional simulations in the late 1980s, people were careful to distinguish true dynamos from just some sort of amplification. Meanwhile, we know of many examples of true dynamos - not only from simulations, but also from several laboratory experiments. Nevertheless, there are still problems, fundamental ones and also very practical ones. After all, we are really not sure how the solar dynamo works. Today, global three-dimensional simulations seem to have an easier time to reproduce the behaviors of superactive stars, but not really the group of inactive stars, to which also the Sun belongs. The Sun itself may actually be special; it has so well defined cycles and it is at the brink of becoming very different. Theoretically, slightly slower rotators should have antisolar rotation, but it is possible that some of those stars never become that slow if stellar breaking ceases for some reason. Sun and starspots are very evident indicators of solar and stellar activity. Their formation is also not well understood. Polarimetry reveals their magnetic helicity, which can be detected even with the solar wind.

The field of Galactic archaeology has been very active in recent years, with a major influx of data from the Gaia satellite and large spectroscopic surveys. The major science questions in the field include Galactic structure and dynamics, the accretion history of the Milky Way, chemical tagging, and age-abundance relations. I will give an overview of GALAH as a large spectroscopic survey, and describe how it is complementary to other ongoing and future survey projects. I will also discuss recent science highlights from the GALAH team and compelling questions for future work.

El Proyecto de SOLARNET se encarga del desarrollo de Unidades de Campo Integral (IFU) basadas en rebanadores de imagen para observaciones solares. El objetivo es alcanzar los requerimientos de EST en cuanto a resolución espacial y Field of View (FoV). La primera IFU desarrollada con un rebanador de imagen de 100 μm de ancho demostró la viabilidad de esta tecnología para espectropolarimetría solar. Ahora, para alcanzar el objetivo es necesario aumentar la resolución espacial y el FoV. Por ello, se han desarrollado dos nuevas IFUs que permitirán validar estos objetivos. Una está basada en tecnología de vidrio (igual que el actual) y el otro en tecnología metálica. Ambas alternativas tienen sus ventajas e inconvenientes y está todavía por confirmar si pueden cumplir los requisitos de EST, en términos de calidad de imagen. En esta charla nos pondremos al día del estado del proyecto y se presentará la última IFU con un rebanador de 35 μm que actualmente está siendo desarrollada. 

https://youtu.be/BJJWKgBeUPY

One prediction of ΛCDM is the existence of partially phase-mixed substructures from accreted dwarf galaxies in the Milky Way stellar halo. Substructure originating in a single accretion event can be readily identified as a tight cluster of stars in phase space with similar chemical properties. Recently, the discovery of the Gaia Sausage Enceladus (GSE) has revolutionised our understanding of the complex assembly of the Milky Way halo. We present a review of the chemistry that characterises the last major merger that happened to the Milky Way some 9-10 Gy ago.

Insights on the shape and nature of the ionizing continuum in astronomical objects are usually inferred via indirect methods as high energy photons are absorbed by our Galaxy. This talk will discuss the relevance of high ionization-potential coronal lines as unique tracers on the ionizing continuum  of active galactic nuclei (AGN), and of active black-hole in general.Focussing on AGN,  using bona-fide black-hole  masses from reverberation mapping and the strong infrared coronal line [Si vi] 1.96 um, a novel BH-mass scaling relation of the form log(M_BH) = (6.40 ± 0.17) − (1.99 ± 0.37)× log ([Si vi] / Brγ_broad) over  the BH mass interval, 10^6 − 10^8 Mo, is found. The dispersion of the relation is 0.47 dex, comparable with that of the canonical "M-sigma" relation.   Following on the thinaccretion disc approximation and after surveying a basic parameter space for coronal lines production, we believe a main driver of the relation is the effective temperature of the disc, which is effectively sampled by the [Si vi] 1.96 um coronal line. By means of CLOUDY photoionisation models, the observed anti-correlation appears formally in line with the thin disc prediction Tdisc prop M_BH^(-1/4).

Zoom:

https://rediris.zoom.us/j/5614942498
Meeting ID: 561 494 2498

YouTube:

https://youtu.be/lfYhJ0pMwTY

I will present the Cosmology and Astrophysics with MachinE Learning Simulations (CAMELS) project, whose main goal of the project is to provide theoretical predictions for observables as a function of cosmology and astrophysics by combining thousands of state-of-the-art cosmological hydrodynamic simulations with machine learning. I will first introduce the simulations and their characteristics. Next, I will present a few results from the CAMELS collaboration, such as the finding of a universal relation between subhalo properties, the usage of convolutional neural networks to marginalize over astrophysics effects at the field level, a constrain on the mass of the Milky Way and Andromeda using graph neural networks, and the prospects of inferring cosmological parameters with a single galaxy.

Join Zoom Meeting
https://rediris.zoom.us/j/81173800387?pwd=Q3hvV0trbnlXeTQ2SzZVS1JveGZZUT09
Meeting ID: 811 7380 0387
Passcode: 437953

YouTube: https://youtu.be/qCYFAh9te_Y

Galactic globular clusters have always been at the crossroad of several investigations
in both Stellar and Galactic Astrophysics. For long time, they have been considered
the prototypes of Simple Stellar Populations, and hence used for testing and calibrating
stellar evolutionary models as well as population synthesis tools. Nowadays, after the 
discovery of the presence of multiple stellar populations in almost all Galactic GCs, we know
that this assumption is no longer valid. The process(es) of formation and early evolution 
of these star clusters is (are) very far to be understood, and any scenario so far envisaged is
severely challenged by the pletora of empirical evidence collected till now. In the same time,
thanks to the availability of an impressive observational framework - collected by combining
kinematic measurements from Gaia mission, with data provided by large spectroscopic and 
photometric surveys -, GCs are playing a crucial role for our understanding of the
assembly history of the Milky Way.
We will review our present knowledge about these important stellar systems, discussing the 
several, open issues related to their formation/evolution, and discuss how we can use them
in our effort to depict the Milky Way assembly history.