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- ItemHigh-Resolution Optical IFU Spectroscopy of the Complex Galaxy Merger II Zw 096(2025) Riesco Bravo, Clemente; Treister, Ezequiel; Pontificia Universidad Católica de Chile. Instituto de AstrofísicaLuminous and Ultra-luminous IR galaxies ((U)LIRGs) are critical for investigating feedback mechanisms due to a combination of intense star formation (SF) episodes and active galactic nuclei (AGN) in the context of complex galaxy interactions. We conduct a detailed analysis of the local(z = 0.0365) merging system II Zw 096 using the Multi-Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope (VLT), combining high-resolution Narrow Field Mode (NFM) and wide-area Wide Field Mode (WFM) observations. We mapped the morphology, kinematics, and ionizing radiation of the system’s gas by fitting atomic emission lines, and analysed the kinematics, age, and metallicity of the stellar population by fitting the continuum. We identify three or more distinct galaxies within II Zw 096, in contrast to previous studies suggesting the presence of only two. Our analysis reveals rotational patterns in the gas and stellar components, as well as complex interactions consistent with a collapsing small galaxy group. The kinematics and ionization structures suggest high star formation rates, shock-driven processes and post-Starburst events, which align with this proposed scenario. Focusing on the D1 compact region, which contributes 40–70% of the system’s IR emission, and combining information from archival multi-wavelength observations from Chandra and ALMA, we find strong evidence for the presence of a heavily obscured AGN powering it. Our analysis of the internal structure, interactions, and merger state of II Zw 096 offers novel insights into the galaxy evolution processes taking place in this dynamic and highly chaotic system.
- ItemEnhanced pixelated modeling of group and cluster scale lenses: Getting ready for Vera Rubin(2025) Urcelay Solís de Ovando, Felipe José; Barrientos, Luis Felipe; Jullo, Eric; Pontificia Universidad Católica de Chile. Instituto de AstrofísicaUpcoming wide-field surveys like LSST and Euclid will uncover thousands of strong gravitational lenses, enabling statistical studies of lens properties, tracing mass distributions from galaxies to clusters, and probing cosmology. While automated modeling exists for galaxy-scale lenses, group- and cluster-scale systems remain challenging due to their complexity.We present a fast, automated method for modeling group and cluster strong lenses, optimized for LSST-like data. The approach combines a large-scale halo with subhalos defined by scaling relations and uses a third-order Taylor expansion for subhalo deflections to improve computational efficiency. The method is memory-light and scales independently of cluster richness.We validate the pipeline on 200 LSST-like simulated lenses (100 clusters, 100 groups), recovering unbiased halo parameters and accurate total masses. Performance improves when selecting lenses with bright arcs or radial features. Application to real SGAS systems yields results consistent with previous models.We discuss possible applications of this method, such as constraining the halo mass function, inner slope of clusters, and subhalo properties. We also outline the necessary extensions for modeling Euclid lenses, which require increased source complexity due to the higher resolution.
- ItemMass Matters 2: Mass and metallicity dependence of the lithium content of Red Clump giants(2024) Del Moral Lobos, Almendra Paz; Chaname Domínguez, Julio César; Pontificia Universidad Católica de Chile. Facultad de FísicaIn this thesis, we study Lithium depletion, intending to better understand how mixing is involved in this process and how mass and metallicity affect its evolution.
- ItemPulsating stellar clocks: Mira variables on the far side of the Galactic disk(2024) Albarracín Contreras, Ricardo Rogelio; Zoccali, Manuela; Pontificia Universidad Católica de Chile. Instituto de AstrofísicaLa estructura y la cinemática del disco de la Vía Láctea se infieren en gran medida a partir de la vecindad solar. Para obtener una comprensión completa, es esencial encontrar trazadores confiables en regiones menos exploradas como el bulbo y el lado lejano del disco. Las variables Mira, que son velas estándar brillantes y bien estudiadas, ofrecen una excelente oportunidad para rastrear poblaciones intermedias y antiguas en estas regiones. Nuestro objetivo es aislar una muestra pura de variables Mira en el estudio Vista Variables en la Vía Láctea utilizando algoritmos de procesos gaussianos. Esta muestra se utilizará para estudiar poblaciones de edad intermedia y antigua en el bulbo galáctico y el disco lejano. Se procesó la fotometría de series temporales en el infrarrojo cercano y medio utilizando algoritmos de procesos gaussianos para identificar variables Mira y modelar sus curvas de luz. Calibramos criterios de selección con una muestra inspeccionada visualmente para crear una muestra de alta pureza de variables Mira, integrando fotometría multibanda y datos cinemáticos de movimientos propios. Presentamos un catálogo de 3.602 variables Mira. Al analizar la fotometría, las clasificamos según su química superficial rica en oxígeno o carbono y derivamos relaciones de extinción selectiva a total de A_{K_{s}}/E(J - K_{s}) = 0.471 \pm 0.01 y A_{K_{s}}/E(H - K_{s}) = 1.320 \pm 0.020. Usando la relación período-edad de las variables Mira, encontramos evidencia que respalda la formación de adentro hacia afuera del disco de la Vía Láctea. La distribución de movimientos propios y distancias se alinea con la curva de rotación galáctica y la cinemática del disco. Extendemos la curva de rotación hasta un radio galactocéntrico de aproximadamente 17 kpc y no encontramos evidencia fuerte del disco estelar nuclear en nuestra muestra de variables Mira. Este estudio constituye el catálogo más grande de estrellas variables en el lado lejano del disco galáctico hasta la fecha.
- ItemExploring Super-Chandrasekhar Supernova SN2007if with radiative transfer code TARDIS(2024) Silva Beyer, Joaquín; Clocchiatti, Alejandro; Pontificia Universidad Católica de Chile. Instituto de AstrofísicaSuper-Chandrasekhar Supernovae (SNe) are a peculiar case of Type Ia SNthat show very high luminosities, slow light-curve evolution, and low expan-sion velocities, consistent with progenitor masses over the Chandrasekharlimit (≳ 1.4M⊙). SN 2007if is one of those events, with a still unknownexplosion scenario. Its early spectra are smooth and near featureless, butat later epochs, they seem to morph into a normal Type Ia. I exploredits spectra with radiative transfer code TARDIS, using three models, con-sidering the envelope interaction and the violent merger hypotheses. Thebest model, based on the envelope interaction scenario, resulted in a verygood match for early epochs, and a better match in the later epochs than theother models. I performed abundance tomography and adapted its chemicalstructure, resulting in my model 07if-tail. While it had a good agree-ment with the observed low velocities and some lines, many still featuredtoo deep absorption profiles, and the lines suggested a lower temperaturethan the overall continuum. I found that SN2007if probably lacks S and hasno Fe on its outer regions. In order to explain SN2007if’s light curve andspectra, a secondary source of continuum brightness is needed. My findingssupport the scenario of a WD-WD slow merger, forming a CO envelope thatinteracts with the explosion’s ejecta.