Recent Talks

Strong gravitational evidence at galactic, extragalactic and cosmological scales exists to believe that most of the matter in our Universe, i.e. up to ∼85% of the total, is dark and non-baryonic. Yet, this dark matter (DM) has not been directly detected. Some of the most preferred scenarios suggest that DM consists of Weakly Interacting Massive Particles (WIMPs), which interact mostly gravitationally with baryonic matter.

The fundamental laws of physics known to date suggest that equal amounts of matter and antimatter should have been produced, and annihilated, during the Big Bang. Yet, observations show that antimatter is present at most in tiny traces is the Solar System and Milky Way neighbourhood, and that a perfect symmetry between matter and antimatter is ruled out at the scale of the entire Universe. In this seminar I will present a review of the observations that characterise the matter-antimatter asymmetry in the Universe and I will briefly outline some theories that try to explain it. I will conclude by presenting some recent observational results that may indicate cracks in the current paradigm that the Universe has been free of antimatter domains since its early phases.

The evolutionary connection between thick and thin disks is still a matter of debate, while observations of high-redshift galaxies have recently shown that stellar disks of various thicknesses emerged very early in the universe. Their diversity seeded the large variety of properties observed in the local universe. Zooming into the spatially resolved stellar populations of very nearby galactic disks traces the story of spiral and lenticular galaxies, from the early stages to recent times. I will present my contribution on this topic, combining high-quality integral-field spectroscopy (IFS) observations of edge-on galaxies with high-resolution numerical simulations.Our recent studies have revealed different stellar populations of nearby thick disks in different types of galaxies, with different star-formation rates (SFRs), suggesting that they result from different evolution histories. The sharp transition, in earlier-type disk galaxies, between old, metal-poor and alpha-enhanced thick disks, and younger metal-rich thin disks, suggests that they formed in two distinct evolution phases. Highly star-forming late-type galaxies, with little differences between relatively young and metal-poor thick and thin disks, suggest a slower upside-down formation. I will finally compare these observations with AURIGA zoom-in cosmological simulations of Milky Way-mass galaxies, revealing one other piece of the puzzle: the connection between the fraction of in-situ and ex-situ stars and stellar-population properties. In these simulations, younger thick disks are explained by later and more massive mergers. These not only contribute younger stars from accreted satellite galaxies, but also large amounts of gas to extend off-plane star formation in time.

n this talk, we will explore innovative approaches to dark matter detection, building upon the foundations of conventional methods. We begin with a concise overview of established detection techniques before delving into direct and indirect detection strategies. For indirect detection, we analyze X-ray data from INTEGRAL/SPI and cosmic-ray positron measurements from AMS-02, leveraging these observations to impose stringent constraints on the decay of dark photon dark matter. In the context of direct detection, we highlight the potential of low-threshold detectors for probing boosted dark matter. Finally, at the intersection of indirect and direct detection, we discuss the novel concept of utilizing celestial objects as natural dark matter colliders and detectors, offering a unique avenue to constrain interactions between dark matter and the Standard Model.

Durante la visita a México, el IAC ha realizado la integración del multiplexor dentro del criostato, enfriado y pruebas del software de mecanismos, control de temperatura del detector y control del detector en si mismo, obteniendo imágenes de prueba y curvas de enfriamiento y calentamiento del criostato.

Durante el resto de la visita, se integró el detector de Ingeniería y siguieron las pruebas de software para asegurar el correcto funcionamiento de los distintos módulos desarrollados.
También se hablará de los avances en el MAD, MCT y control automático de temperatura del detector.

The most massive elliptical galaxies are known to exhibit a central deficit of stars. These depleted "cores" are believed to form through dry mergers between early-type galaxies (ETGs) via a process called core scouring. In this process, stars are ejected from the center due to interactions with the merging black holes of the gas-poor progenitor galaxies. This phenomenon leaves a distinct imprint on the stellar distribution, making it a valuable tracer for investigating the formation history of ETGs.

To study this effect, a dynamical model is required that can recover the intrinsic orbit structure and mass distribution of the galaxy under study. We developed a novel, state-of-the-art dynamical Schwarzschild modeling technique, capable of recovering the intrinsic structure of even triaxial systems with an unprecedented precision.

Applying this model to high-resolution MUSE spectral data of the massive core elliptical galaxy NGC 5419, we identified an ideal candidate to investigate the dry-merging scenario of ETGs in greater detail. NGC 5419 has a well-depleted core, yet HST data reveal a double nucleus, suggesting that two supermassive black holes (SMBHs) from the progenitor galaxies have not yet completely merged.

We find that NGC 5419 is observed in an intermediate stage of core evolution, hosting an as-yet-unmerged SMBH binary system. NGC 5419 is the first galaxy observed in this transitional state, providing previously unobserved insights into the formation mechanism of ETGs.

Our dynamical models of NGC 5419 reveal a total SMBH mass of Mbh = (1.0 ± 0.08) × 10^10 Msol, establishing NGC5419 as host to one of the most massive BHs discovered in the local universe so far.

En este seminario se presentan los componentes software del sistema de control GCS que controlan el encendido de los diversos componentes de los armarios de los instrumentos y también el control de temperatura de los armarios.

Albeit rare in absolute numbers, massive stars are shaping our cosmic history as they are connected to many astrophysical key processes. Commonly defined as stars with an initial mass of more than 8 times the mass of our Sun, massive stars are the progenitors of black holes and neutron stars, reaching all nuclear burning stages before eventually undergoing their inevitable core collapse. In their comparably short life, these luminous objects have an enormous impact on their galactic environment, enriching the surrounding medium with momentum, matter, and ionizing radiation. This so-called "feedback" of massive stars is a building block for the evolution of galaxies, initiating and inhibiting further star formation. In the "afterlives" of massive stars, black holes and neutron stars can merge with each other, giving rise a to Gravitational Wave events. Yet, overall textbook picture typically drawn of massive stars is rather sketchy and often also at odds with observational constraints. New frontiers such as the strong metal-enrichment in high-redshift galaxies discovered by JWST or the black hole statistics obtained from Gravitational Waves only add further pieces to the enigmatic massive star puzzle.

For a better understanding of massive stars, it is essential to properly determine their parameters and feedback. For young and hot massive stars, many properties are only accessible via spectroscopy. Their quantitative measurements and predictions rely on suitable models for stellar atmospheres, which requires sophisticated simulations to account for their non-equilibrium conditions and strong stellar winds. In this talk, I will introduce the techniques and challenges of atmosphere modelling for hot, massive stars and their winds. Afterwards, I will present a selection of the research efforts within my group demonstrating the range of empirical and theoretical applications of modern non-LTE stellar atmosphere models, such as the analysis of important landmarks of massive star evolution, the search for "hidden" post-interaction binaries, or theoretical insights on radiation-driven winds. Finally, I will give an outlook on current observational challenges and theoretical insights from 2D and 3D simulations raising a new need to reconsider some of the current paradigms in massive star atmosphere modelling.

Strongly lensed supernovae are extremely rare and powerful probes that can give insights into high-redshift supernova physics, substructures in massive galaxies, and the expansion rate of the Universe. Currently, the lensed supernova field is at a turning point, as we will go from a handful of present discoveries to several hundreds per year with the advance of the next generation of telescopes. In this talk, I will present the current state of the lensed supernova field and future developments. Beginning with the discovery story of ‘SN Zwicky’, a lensed type Ia supernova found with the Zwicky Transient Facility, I will take you on a visual journey, using beautiful observations to highlight our discoveries about SN Zwicky, its exceptionally light lens galaxy, and implications for stellar microlensing. Finally, we will look ahead at the upcoming Vera Rubin Observatory and how it will help us discover more lensed supernovae and refine our understanding of the Universe’s expansion.