3.16 Tesis magíster
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Browsing 3.16 Tesis magíster by Subject "520"
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- ItemA VLT/MUSE galaxy survey towards QSO Q1410 : looking for a WHIM traced by BLAs in inter-cluster filaments(2018) Pessa Gutiérrez, Ismael Alejandro; Tejos, Nicolás; Barrientos, Luis Felipe; Pontificia Universidad Católica de Chile. Instituto de Astrofísica
- ItemBlue Stragglers in the Gaia Era: Galactic Open and Globular Clusters(2023) Carrasco Varela, Francisco Felipe; Puzia, Thomas H.; Pontificia Universidad Católica de Chile. Instituto de AstrofísicaBlue Straggler Stars (BSSs) are one of the keys to understand in a better way how stars evolve and interact with each other in different star clusters. They appear to be hotter and brighter than the Main Sequence Turn Off Point (MSTO) and, therefore, they should have evolved off the Main-Sequence branch. We properly select, for Open Clusters (OCs) and Globular Clusters (GCs), star cluster members based on proper motions and parallaxes provided by Gaia Data Release 3 (DR3). Using isochrones models and selection criteria from previous studies, we select and classify stars as BSS, Yellow Straggler Stars and Red Stragglers Stars (evolved BSSs). We identify BSSs to be present in all our GCs and in 42/129 (∼ 33 %) of studied OCs. We counted a total of 4399 BSSs; 434 (∼ 10 %) located in OCs and 3965 (90 %) located in GCs. Clusters younger than ∼ 500 Myr do not show the presence of BSSs in our sample. We obtain astrophysical parameters from 3 different methods (color–temperature relations, isochrone–fitting models and parameters from Gaia DR3 spectra) such as the effective temperature Teff, star mass M, and surface gravity log(g). We find values for BSS Teff to be ∼ (6800 ± 585) K in GCs and ∼ (7570 ± 1400) K in OCs; and an average mass of ⟨MBSS⟩ = (1.75 ± 0.45) M⊙ in OCs and ⟨MBSS⟩ = (1.02 ± 0.1) M⊙ in GCs. For every BSS, we compute the difference of the BSS mass and the MSTO mass of its parent cluster, normalized by the MSTO mass, and called it Me based on previous studies. This parameter is classified as low–Me (Me < 0.5, BSS likely formed through mass-transfer) and high–Me (0.5 < Me < 1.0, BSS likely formed through mergers). For OCs we find a percentage 81.34 % high–Me and 18.66 % low–Me. For GCs, we find 94.25 % low–Me and 5.25 % high–Me. Comparing Me against the BSS age obtained with isochrone modes, we were able to detect: i) GC BSSs that are most likely to be formed through collisions show a “boost” in their percentage/fraction for stars with an age ∼ 1 − 2 Gyr, in agreement with reported age for core-collapse events in GCs found in previous studies; ii) a double sequence for GC BSSs, where we conclude that these sequences correspond to a pre merger/closer-binary interaction and post merger/closer-binary interaction of BSS formation
- ItemComputer vision and machine-learning method for the detection of low-surface brightness galaxies in the Fornax Cluster(2024) Hernández Flores, Alejandra Valentina; Puzia, Thomas H.; Pontificia Universidad Católica de Chile. Instituto de AstrofísicaDetecting the faint luminosity in Low Surface Brightness Galaxies (LSBGs) poses significant challenges, primarily due to sky brightness and contamination from brighter sources while separating LSBGs from the background. Despite these challenges, the study of LSBGs holds great potential to advance our understanding of various fields, including cosmology, galaxy formation, evolution, and the characteristics of galaxy clusters. The primary goal of this study is to develop an automated code capable of effectively detecting LSBGs, including the more diffuse LSBGs that are only detectable through visual search. The initial focus is on the Fornax cluster of galaxies, with the possibility of extension to other galaxy clusters. The purpose is to significantly contribute to advancing research in LSBGs and its implications for broader astronomical studies. We have created an automated code that successfully detects LSBGs in digital images at a reasonable processing speed. We have incorporated an innovative algorithm to separate LSBGs from the background using a dynamic background kernel and threshold applied to image segments to achieve this. We have also implemented a bilateral filter that identifies the most diffuse LSBGs and preserves morphology, ensuring precise identification and classification. Additionally, we have developed and trained a One-Class Support Vector Machine (SVM) classifier using a gold sample of 143 LSBGs, resulting in a classifier with a low rate of false positives. The implemented code has successfully detected LSBGs, showcasing its ability to address the challenges associated with identifying the faint luminosity in these galaxies, even in the presence of brighter sources. The integrated algorithm has significantly improved the accuracy and efficiency of the detection process, allowing for the identification of a substantial number of LSBG candidates. Specifically, in the Fornax Cluster, our algorithm successfully identified 31,295 LSBG candidates, as documented in the comprehensive catalog available at GitHub Repository: \url{https://github.com/Alevhf/LSB_candidates/blob/main/Catalog_result.csv#L19304}.
- ItemEstimadores de metalicidad en SN tipo II-P(2023) Castro Morales, Nicolás Manuel; Clocchiatti, Alejandro; Pontificia Universidad Católica de Chile. Instituto de AstrofísicaUno de los parámetros más difíciles de estimar en supernovas es su metalicidad, basicamente por lo complejo de sus espectros y por la imposibilidad de haber observado con el detalle apropiado al progenitor en la gran mayoría de los casos. Los espectros de las supernovas de tipo IIP durante la fase fotosférica, sin embargo, revelan información directa sobre la metalicidad de la estrella progenitora que es posible interpretar. Los pseudo anchos equivalentes de los perfiles P Cygni de líneas de elementos químicos complejos ya han sido utilizados como indicadores de metalicidad, pero tienen algunas limitaciones. Presentamos un nuevo método que añade a las líneas de los espectros un indicador fotométrico basado en la evolución del brillo de las supernovas en la banda B, y/o la U, de Johnson, siempre en supernovas tipo IIP. Usando modelos teóricos de la atmósfera en estas supernovas encontramos que la variación de la magnitud en B entre las fases temprana y tardía de la curva de luz (EtoLC, por las siglas en inglés, de ``Early to Late Contrast'') está relacionada tanto con la masa como con la metalicidad del progenitor. Mostramos además que con el uso combinado de los anchos equivalentes de una línea de hierro y estos EtoLCS es posible discriminar con bastante sensibilidad y separar supernovas provenientes de la explosión de progenitores muy masivos de las provenientes de progenitores poco masivos, así como los que tenían metalicidad elevada de los que la tenían baja. Utilizando esta técnica a una muestra de supernovas reales, con buenos conjuntos de datos como para poder medir estos parámetros, se encuentra concordancia con lo ilustrado por los modelos indicando que, una vez calibrado, el método tendrá el potencial de poder encontrar con observaciones directas las características de masa y metalicidad de los progenitores de SN tipo IIP.
- 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.
- 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.
- ItemStatistical study of neutron star glitches(2018) Fuentes Baeza, José Rafael; Reisenegger, Andreas; Espinoza, Cristóbal; Pontificia Universidad Católica de Chile. Instituto de Astrofísica