Recent Talks

List of all the talks in the archive, sorted by date.

Thursday March 9, 2023
Dr. Robert Szabo
Konkoly Observatory


Kepler photometry was so precise that new ways could be developed to harvest the great wealth of quasi-continuous data that has never been accessible from the ground. We initiated a project that we dubbed The Kepler Pixel Project in order to explore approaches and to discover new pulsating stars and other time-variable objects. During the project we examined individual pixels of the original Kepler mission to find interesting objects around the main Kepler targets. Specifically we launched a subproject to find background, faint RR Lyrae stars that are missing from the original Kepler sample. Altogether we found 26 new RR Lyrae stars, increasing the Kepler original RR Lyrae sample by 50%. In this talk I'll present the latest results of this project. In addition to RR Lyrae stars I will also show results on ~1000 new eclipsing binaries found in the framework of the same project.

Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST) is one of the most important ground-based astronomy projects of the coming decade. In the second half of this talk I will present my research group's work on classification of variable stars with machine learning methods which is part of the Hungarian in-kind LSST contribution. The novelty of our method is that we use images of light curves, such as a human classifier would do. The method gives surprisingly good results based on the shape of light curves only, but can be further improved if additional astrophysical parameters (distance, amplitude, colors, etc.) are taken into account.

Tuesday March 7, 2023
Dr. Eduardo Balbinot
Kapteyn Institute at the University of Groningen


Only recently, thanks to the Gaia, have we been able to directly measure how our own Galaxy was formed since its infancy, by cannibalizing smaller galaxies formed at the core of dark matter subhalos. These accretion events can be seen as kinematic groups and may have brought their own group of globular clusters, some of which are only seen today as their remnant cold stellar streams. Here I will discuss how the main accretion events unveiled by Gaia can be linked to previously known halo substructures, mainly large stellar clouds identified more than a decade ago in large photometric surveys. Additionally I will discuss the Jhelum stellar stream in the light of its interaction with the Sagittarius stream, which can give us insight on the details of this ongoing accretion event. Finally, I will briefly discuss how the new Gaia XP DR3 spectra is aiding in  the identification of metal-poor unmixed halo substructures in the solar neighbourhood, highlighting the case of ED-2, a [Fe/H] = -2.5 cold stellar stream in which the Sun is embedded in. 

Finally, I will briefly discuss how the new Gaia XP DR3 spectra is aiding in  the identification of metal-poor unmixed halo substructures in the solar neighbourhood, highlighting the case of ED-2, a [Fe/H] = -2.5 cold stellar stream  in which the Sun is embedded in.

Tuesday March 7, 2023
Dr. Antonio Cabrera-Lavers


In this talk, I'll describe the full upgrade of OSIRIS at GTC telescope, once installed in the Cassegrain focal station including a new monolithic blue-sensitive detector. Changes in the standard operation of the instrument will be detailed, as well as a brief summary of the short-term instrumentation plan for GTC in 2023.


Unirse a la reunión Zoom
ID de reunión: 869 8574 0449

Enlace de Youtube:

Friday March 3, 2023
Adrián Calzadilla González


La finalidad del proyecto TTNN es realizar la mejora del sistema de control de los telescopios IAC-80 y Carlos Sánchez con el objetivo que el nuevo entorno de software y hardware que se diseñe sea robusto
versátil, permitan controlar los telescopios de forma remota y facilitar, a posteriori, su operación automática. Para el cumplimiento de estos requerimientos en la parte software se está diseñando e implementando un sistema de control de alto nivel basado en ROS y una aplicación de escritorio escrita en pyQt5.


Thursday March 2, 2023
Dr. Carlo Cannarozzo



Early-type galaxies: instructions to build them through mergers
Massive early-type galaxies (ETGs) are "red and dead" systems mainly composed of old and metal-rich stellar populations. In a cosmological context, present-day ETGs are believed to be the remnants of a complex stellar mass assembly history marked by several mergers, which are the consequence of the underlying hierarchical assembly of their host dark matter halos. In this talk, I will deal mainly with the merger-driven evolution of ETGs. Firstly, I will illustrate a comparison between observed ETGs from the MaNGA survey and simulated galaxies from the IllustrisTNG cosmological simulation suite. The aim of this study is to provide an interpretative scenario of the stellar mass assembly history of observed present-day ETGs, comparing the radial distributions of their stellar properties with those of simulated galaxies, in which it is possible to disentangle the contribution of stars formed in situ (i.e. within the main progenitor galaxy) and stars formed ex situ (i.e. in other galaxies) and then accreted through mergers. Then, I will describe how the scaling relation between the stellar mass and stellar velocity dispersion in ETGs evolves across cosmic time. Specifically, by extending the results of Cannnarozzo, Sonnenfeld & Nipoti (2020), I model the aforementioned relation through a Bayesian hierarchical approach, considering ETGs with log(M∗/M⊙) > 9 over the redshift range 0 ≲ z ≲ 4. Together with a new characterisation of the relation, I reconstruct the back-in-time evolutionary pathways of individual ETGs on the stellar mass-velocity dispersion plane to answer the question “how did high-redshift ETGs assemble through cosmic time to reach the functional form of the relation in the present-day Universe?“.
After the main topic, if time permits, I would like to spend a few minutes presenting another extra content (below you can find the title and a brief abstract of this further content). Feel free to include it or not in the announcement mail.
EXTRA - Inferring the Dark Matter halo mass in galaxies from other observables with Machine Learning
In the context of the galaxy-halo connection, it is widely known that the Dark Matter (DM) halos show correlations with some physical properties of the hosted galaxy: the most well-known relation is the so-called Stellar-to-Halo-Mass Relation. However, we know that there are several other empirical relations among galaxy properties, involving, for example, the stellar mass, the gas and stellar metallicities, the black hole mass, etc. Given the complexity of the problem and the high number of galaxy properties that might be related to DM halos, the study of the galaxy-halo connection can be approached by relying on machine learning techniques to shed light on this intricate network of relations. With the aim of inferring the DM halo mass and then finding a unique functional form able to link the halo mass to other observables in real galaxies, I rely on the state-of-the-art Explainable Boosting Machine, a novel implementation of generalised additive models with pairwise interactions, training a model on the IllustrisTNG simulation suite at different redshift.





Tuesday February 28, 2023
Dr. David Jones


MAAT is a mirror-slicer integral field unit that will be installed in OSIRIS in 2024, breathing new life into the GTC's work horse instrument. As well as the opportunity to perform spatially-resolved spectroscopy over a field of 10"x7", MAAT will also offer increased signal-to-noise and resolution for point sources with respect to the standard long slit mode.  As part of the preparations for the arrival of MAAT, we have implemented support for the reduction of OSIRIS data into the open-source, python-based spectroscopic reduction package PypeIt. Indeed, with the arrival of the new blue-sensitive CCD, PypeIt is now the only publicly available pipeline that continues to work for OSIRIS. With very little human intervention, PypeIt produces fully calibrated and coadded spectra that are near the Poisson limit for point sources. In this talk, I will present a brief overview of the philosophy behind PypeIt and demonstrate the ease with which OSIRIS data (and soon MAAT data) can be reduced.


Thursday February 23, 2023
Prof. Mauro D'Onofrio
University of Padova


I present a detailed analysis of the scaling relations of ETGs and suggest a way to predict the evolution of the distributions of galaxies in these planes. This new approach is able to account of several features observed in the FP projections and of the tilt of the Fundamental Plane.


Friday February 17, 2023
Gabriel González Rial


El próximo proyecto en estudiar es fondo cósmico de microondas (CMB) es LiteBIRD, un satélite de la JAXA que pretende estudiar la polarización de los modos-B. En él se encuentran integrados tres telescopios que recorren un rango frecuencial desde los 34 hasta los 448 GHz, donde se encuentran los Transition-Edge Sensor Detectors (TES), que operan a una temperatura de 100mK y que requieren de una estabilidad térmica estricta. En el Instituto de Astrofísica de Canarias se están estudiando mecanismos de control de la temperatura para convertir los requisitos térmicos en una realidad.


Thursday February 16, 2023
Dr. Rogério Riffel
Astronomy Department of the Physics Institute of the Federal Universisty of Rio Grande do Sul (UFRGS)



Since the pioneering studies linking the mass of supermassive black holes (SMBH) with the velocity dispersion of their host galaxies bulges it has become accepted that the products of active galactic nuclei (AGN) accretion and star-formation (SF) are somehow related. It is also accepted that nuclear SF and AGN can coexist in the inner region of galaxies, suggesting that the growth of SMBH (by gas accretion) and galaxies (by forming stars) are coupled.  In terms of galaxy evolution, it is established that AGN feedback plays a fundamental role by impacting SF (quenching, suppressing, or triggering). Cosmological simulations performed without the inclusion of feedback (SNR/AGN) effects are not able to reproduce the low and high luminosity ends of the galaxy luminosity function and underestimate the ages of the stars of the most massive galaxies when compared with observations.  While observations have shown that nuclear star formation is common in AGNs, properly measuring the stellar population properties in AGNs hosts is particularly difficult, since the active nucleus will dilute the absorption features and contribute to a large number of ionizing photons that will make it difficult to use emission line fluxes to infer the stellar properties.  In this seminar, I will discuss the results we have obtained in our group when mapping the stellar population in the inner region of active galaxies, with a special focus on the near-infrared spectral region, which allows for a better untangling of the AGN and stellar contributions for the spectral energy distribution of the galaxies. 

Meeting ID: 817 0462 3667
Passcode: 643393

Tuesday February 14, 2023
Dr. Nicolas Martin
Observatoire Astronomique de Strasbourg


Dwarf galaxies are powerful tools of near-field cosmology and galactic archaeology: their numbers, distribution, and star formation can be linked to both the tenets of LCDM (the missing satellite "problem," their (an)isotropic distribution, their dark matter content) and to the build up of their hosts and their environment (accretion, quenching). The exquisite detail offered by observation of the nearby Milky Way dwarf galaxies has built a picture of what dwarf galaxies are and how they evolved through time. In this talk, I will review the increasingly sharp view we are building of the dwarf-galaxy system of the Milky Way's "sister" galaxy, Andromeda, and emphasize key similarities and differences between these two systems of satellites in the hope to learn what features are common or, on the contrary, driven by the different pasts of the Milky Way and Andromeda.

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