Recent Talks

Activity of cool dwarf stars can reveal itself in the form of high-energy radiation (eg, enhanced X-ray coronal emission, flares) and particles (eg, winds, coronal mass ejections). Together, these phenomena shape the space weather around (exo)planets. Because most of the known exoplanets have significantly closer orbital distances than solar system planets, they are often embedded in much harsher particle and radiation environments, leading to stronger interactions between the exoplanet and its surrounding environment. In this talk I will present an overview of how stellar activity and outflows can induce and shape atmospheric escape in exoplanets. I will focus mostly on close-in gas giant planets, whose escaping atmospheres are somewhat easier to observe. I will then discuss how the observability of atmospheric escape, through spectroscopic transits, evolve on billions of years timescales.

The coupling between the baryonic cycle of galaxies and dark matter halo assembly is central to our understanding of galaxies, and yet, it remains a challenge for theoretical models and elusive to observations. In this talk, I report observational evidence demonstrating that different baryonic properties of nearby galaxies are controlled by their host halos. We map galaxy ages, metallicities and star formation histories across the stellar-to-halo mass relation for SDSS central galaxies using absorption optical spectra. In addition to stellar populations, we also investigate the stellar angular momentum, star formation rates and galaxy morphology across the stellar-to-total dynamical mass relation for CALIFA galaxies. We find that the scatter of both relations correlates with these galaxy properties, which are determined by the combined role of stellar and halo/total mass. Galaxies become older, more metal-rich and less rotationally supported, form the bulk of their stars earlier on and faster, have lower star formation rates and earlier-type morphologies as their stellar mass increases (at fixed halo/total mass). Furthermore, we also observe that the scatter of the star-forming main sequence is driven by galaxies that have experienced different evolutionary histories. We interpret our results as being driven by halo evolution, with galaxies/halos at different evolutionary stages modulating the variety of galaxy properties observed at fixed stellar mass. Our findings call for a revision of the sub-grid physics implementation in cosmological numerical simulations, in particular during the early stages of galaxy formation, and warn observational studies to account for the profound effect that halo formation time may have on measured galaxy properties.

Zoom Link: https://rediris.zoom.us/j/96210828127?pwd=Z25JdFg1bnpRTVBSQUdpTVlwUDgyQT09

El objetivo de esta charla es presentar los recientes avances del sistema de Óptica Adaptativa de GTC (GTCAO). Se resumirán los resultados de las pruebas de aceptación en la sala AIV en abril de 2023; las dificultades y el éxito del transporte al ORM y la instalación en GTC en junio de 2023; la integración del sistema con el control del telescopio y los primeros resultados de las campañas de commissioning en cielo. Se repasará también brevemente el estado del resto de proyectos del programa, en concreto el sistema de Estrella Guía Láser y el instrumento GRANCAIN.

Feedback from accreting supermassive black holes (aka active galactic nuclei, AGN) is thought to be key in shaping the life-cycle of galaxies. AGN inject a significant amount of energy into the surrounding interstellar medium and launch gaseous winds. They are therefore able to potentially inhibit future star formation in their hosts. An ideal cosmic laboratory to study how AGN regulate galaxy growth is the so-called cosmic noon (z~2), i.e. the peak of AGN accretion activity, when their energy output is overall maximized. In this talk I will describe our recent efforts to systematically characterize the impact of AGN on star formation in galaxies at cosmic noon. To this aim, we are exploiting integral field spectroscopy data obtained with SINFONI and ALMA observations of the ionized and molecular gas as well as dust continuum. In addition, I will discuss a complementary avenue to build a statistical understanding of AGN feedback across the galaxy population by using spectroscopic surveys, less time consuming than integral field spectroscopy and able to collect large samples of thousands of targets.

Zoom link: https://rediris.zoom.us/j/99761131815?pwd=QUN0ckRSZWJZQkh1aUxvSU9UNmtJUT09
Meeting ID: 997 6113 1815

Passcode: 164994

El presente trabajo analiza cómo es el proceso de gestión del conocimiento científico en el Instituto de Astrofísica de Canarias (IAC) como caso paradigmático de un entorno de coopetición donde se coopera y se compite en aras de lograr la excelencia científica. Para ello se ha llevado a cabo un estudio cualitativo y cuantitativo del Área de Investigación del IAC, que ha permitido tener una visión de los diferentes aspectos que determinan dicho proceso (capital humano, social y organizativo; capacidades directivas y prácticas de RRHH). Además de evidenciar los principales hallazgos sobre el bienestar laboral de los investigadores, también se analizarán los resultados alcanzados desde la perspectiva de género. Finalmente, se presentarán las conclusiones y recomendaciones del estudio.

The Institute for Astrophysics and Geophysics (IAG) in Göttingen operates a Fourier-Transform Spectrograph (FTS) that can be fed by either a 50cm siderostat or an integrating sphere. In 2016, we published a solar flux atlas (disk-integrated) at wavelengths 405-2300nm. Being largely comparable to the Kitt Peak spectral atlases in terms of resolution and signal-to-noise, our focus lies on an accurate calibration of frequencies (wavelengths) because we are interested in absolute convective blueshift of solar surface features.
Recently, we published an atlas of the quiet solar surface at different limb positions (spatially resolved Sun) and investigated convective velocities across the solar surface and in different spectral lines (Ellwarth et al., 2023 and in press). Furthermore, we studied the impact of centre-to-limb variation on exoplanet transit observations (Reiners et al., 2023). We are currently collecting data of active solar regions with the goal to measure convective blueshift as a function of limb position and magnetic field strength. In the talk, I will provide an overview of our program with a focus on the challenges we met in our attempts to determine Doppler velocities at the solar surface at m/s accuracy.

Zoom link: https://rediris.zoom.us/j/97531318437?pwd=TEpGZGVkNkpBcXBLWVlNTGt6bkdNUT09
Meeting ID: 975 3131 8437

Passcode: 147922

Using unsupervised machine learning methods, we present a novel approach to classifying galaxies into early and late types based on their spectral characteristics. The research utilizes a balanced dataset of 2000 galaxies from the Galaxy Zoo 2 and spectral data from the Sloan Digital Sky Survey Data Release 13. The methodology involves applying an Autoencoder Neural Network for dimensionality reduction, followed by a Gaussian Mixture Model for clustering. The study demonstrates that this approach achieves an accuracy rate of approximately 86% in galaxy classification, highlighting the potential of unsupervised machine learning techniques in enhancing the precision and efficiency of morphological classification of galaxies based on spectral data.

In the local Universe, there are a handful of dwarf star-forming galaxies that are young, having formed a large fraction of their stellar mass during their last few hundred Myr. However, little is known about the fraction of young stellar populations in more massive galaxies. Using the data from the Sloan Digital Sky Survey, we identified a surprisingly large sample of more massive, very young galaxies (VYGs), defined to have formed at least 50 per cent of their stellar mass within the last 1 Gyr. In this seminar, I will present our study on the fractions, properties and environment of low-redshift VYGs in observations and simulations, discuss possible mechanisms responsible for the recent triggering of intense star formation activity in these systems, and argue that VYGs can be useful in constraining the uncertainties in both galaxy formation models and spectral modelling of galaxy star formation histories.