Recent Talks

MOONS is a 0.8 to 1.8 microns multi-object spectrometer for the Nasmyth focus of UT1 that is being built by a consortium led by the UK-ATC. The instrument is fibre fed, has a multiplex of 1000 and covers a total field of 25 arc minutes in diameter with a high transmission. There are two spectral resolving powers, ~4000 spanning the full wavelength range and a higher resolution mode which gives ~9000 in the I window and ~20,000 in a region in H windows. The instrument itself has two main parts:

• The rotating front-end which is at the focal plane and houses the fibre positioners, acquisition system, metrology system for the fibres, etc., and
• The cryogenic spectrograph which houses the spectrograph optics, VPH gratings and detectors.

MOONS is now approaching completion and is due to be shipped to Paranal in March 2024. This talk presents the MOONS instrument, the science that it will allow, and its current status.

Nebular emission lines are a powerful diagnostic tool for tracing the chemical evolution in star-forming galaxies (SFGs) across cosmic time. Due to their proximity, SGFs are ideal for studying the physical properties, stellar population, and nebular gas in much more detail. The COS Legacy Spectroscopy SurveY (CLASSY) is a treasury survey that comprises UV+optical spectra of 45 local SFGs covering a broad range of physical properties. In this talk, I present the results of the physical conditions and metallicities for the CLASSY sample focused on the impact of the aperture effects of the inferred metallicities and the abundance patterns of several elements. We found that the results for the inferred electron density, temperature, and metallicity derived using different aperture sizes, 1″-3″, are consistent, indicating a uniform mapping of the nebular gas. We also showed that the physical properties derived from the optical are appropriate for observations in the far-UV, allowing a better interpretation of the interplay between the stellar and gas components. I will also discuss the results of the Ne/O, Cl/O, S/O, and Ar/O vs. O/H relations and their behaviour with different galaxy properties (e.g., stellar mass and star formation rate). We found that such abundance ratios follow a constant trend with O/H as expected, except for Ne/O and Ar/O, which show a significant trend at high metallicities. We discuss the scatter involved in the N/O versus O/H relation and its connection with the different UV+optical observables. Finally, we compare these results with the chemical abundances derived at z > 6 galaxies observed with the JWST.

Se profundizará sobre las tres funcionalidades para el sistema de control del IAC80 en las que se ha trabajado durante el periodo de las prácticas externas en el IAC. 

Youtube

https://youtube.com/live/l3J7pRrcuFc?feature=share

La trazabilidad al sistema internacional de unidades SI de las mediciones espectrorradiométricas de la radiación óptica en multitud de aplicaciones (control de variables climáticas esenciales, procesos industriales, iluminación, asistencia sanitaria, seguridad laboral, generación de energía fotovoltaica, etc.) se ha realizado mediante patrones de transferencia basadas en lámparas de incandescencia. Sin embargo, la disponibilidad de estas lámparas está disminuyendo debido al abandono progresivo de la producción de lámparas de este tipo para la iluminación.

El objetivo de este seminario es discutir sobre otras fuentes de radiación (actuales o futuras) que puedan sustituir de forma adecuada y asequible a las lámparas de incandescencia y sobre procedimientos alternativos a las fuentes de radiación para la transferencia/calibración de medidas de irradiancia espectral en los intervalos ultravioleta, visible e infrarrojo cercano.

Youtube:

https://youtube.com/live/T9uHYGMDIAw?feature=share

Extremely metal-poor or zero-metallicity very massive stars, with initial mass in the range 100 ≲ Mi/M⊙ ≲ 1000, have a broad astrophysical impact. Understanding how these population III stars evolve and die has implications for several key questions, including the nature of energetic transients such as pair-instability supernovæ and gamma-ray bursts, the source of extreme ionizing UV-radiation fields at high redshifts, the earliest chemical enrichment of their host galaxies and the rates of gravitational-wave emission from merging black holes among others. There are not many models in literature that follow the evolution of these population III stars, and even less so that reach the phases where the production of electron-positron pairs alter the stability of the whole star. We present new evolutionary models of very massive primordial stars, with initial masses ranging from 100 M☉ to 1000 M☉, that extend from the main sequence until the onset of dynamical instability. We focus on the final outcome of the models and associated compact remnants. Stars that avoid the pair-instability supernova channel, should produce black holes with masses ranging from ~ 40 M☉ to ~ 1000 M☉. In particular, stars with initial masses of about 100 M☉ could leave black holes of ≃ 85-90 M☉, values consistent with the estimated primary black hole mass of the GW190521 merger event. Overall, these results may contribute to explain future data from next-generation gravitational-wave detectors, such as the Einstein Telescope and Cosmic Explorer, which will have access to as-yet unexplored BH mass range of ~ 10^2-10^4 M☉ in the early universe.

TFG sobre la aplicación de técnicas de aprendizaje automático para la predicción de la temperatura de punto de rocío y su implementación de el Sistema de Control de Telescopios Nocturnos del Observatorio del Teide

Using CGMS deep integral field data we have discovered that the massive galaxy NGC 1277 has no dark matter. This is the first time that a galaxy as massive as the Milky Way or more is found to be dark matter deficient. This result is unexpected within the Lambda-CDM cosmological paradigm. We propose several alternatives to explain this intriguing observation but none is completely satisfactory, so the mystery about how to generate a galaxy without dark matter remains.

Zoom: https://rediris.zoom.us/j/81895121297?pwd=YnVpaTdUVkZvN25RYmkrN2VOV3pEdz09

ID: 818 9512 1297

Passcode: 460746

Youtube: https://youtube.com/live/TMctBBbLn9Y?feature=share

The stellar mass – halo mass relationship is a fundamental scaling relationship connecting galaxies from dwarfs to giants to their dark matter halos. This relationship is currently key to our understanding of the complex interplay between the many modes of feedback (e.g., stellar winds, supernovae, AGN) and star formation in galaxies. However, recently a population of large half-light radius, low surface brightness ultra-diffuse galaxies (UDGs) have questioned our understanding of galaxy formation in the dwarf galaxy regime. UDGs have been found to reside in dark matter halos of widely varying mass. While many likely reside in "normal" dark matter halos for their stellar mass, some may exhibit an extreme lack of dark matter while yet others are extremely dark matter rich. In this talk, I give an overview of the current observational evidence for UDGs residing in massive dark matter halos. I place particular emphasis on my own Keck observations which have provided support for UDGs' unexpected stellar mass – halo mass positioning and that has revealed the internal structure of their halo (i.e., core vs cusp nature). I discuss how these observations currently inform proposed formation scenarios for UDGs and show an outstanding tension of my observations with simulations of galaxy formation. I conclude with a brief discussion of the important future goals of the field.

Interactions between galaxies often leave an imprint that is observable in the aftermath of the interaction, such as tidal features or perturbations in the stellar and gas kinematics of the galaxies. Sometimes these perturbations can be structures (i.e. gas or stars) that are strongly misaligned or even rotating in the opposite direction with respect to the main stellar body of the galaxy. It has been suggested by simulations that misalignment may drive galaxy gas all the way to the central supermassive back hole, one of the ingredients needed to fuel black hole activity. I will show observational evidence that galaxy interactions, such as major mergers, minor mergers or galaxy flybys, indeed provide the necessary conditions to fuel black hole activity and growth. I will present a method that uses kinematically misaligned gas to observationally identify galaxies that went through an interaction. With this method we have recently shown that galaxies that have misaligned gas have a higher observed fraction of active black holes. This is the first time that an observational connection is seen between the process of formation and/or presence of misaligned structures and the fuelling of active supermassive black holes. I will discuss the implications of this black hole fuelling mechanism for different galaxy types and their evolution.