3.10 Facultad de Física

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A search for substructures near the Galactic plane and bulge using RR Lyrae stars as tracers
(2024) Cristi Cambiaso, Nicolas Eduardo; Catelan, Marcio; Zoccali, Manuela; Pontificia Universidad Catolica de Chile. Faculty of Physics. Institute of Astrophysics
Usando estrellas pulsantes de tipo RR Lyrae, hacemos una búsqueda de subestructuras Galácticas ("stellar streams" y cúmulos globulares) en la región del plano Galáctico. Construimos una muestra de estrellas RR Lyrae con valores de distancia y metalicidades. Estudiamos esta muestra con un algoritmo de "clustering" para encontrar grupos de estrellas cercanas y con propiedades similares. Mediante esta búsqueda, recuperamos estructuras conocidas y encontramos posibles nuevas estructuras.
An extensive study of models beyond the standard model
(2020) Maturana Ávila, Ivania; Díaz, Marco A.; Pontificia Universidad Católica de Chile. Instituto de Física
El presente trabajo se centró en el estudio fenomenológico de tres modelos que son extensiones del actual Modelo Estandar: El Inert Higgs Doublet Model, el Scotogenic Model and el Singlet + Triplet Scotogenic Model. La motivación de estudiar estos modelos se basa en que pueden explicar algunas de las preguntas existentes en física hoy en día; todos ellos presentan una particula que será candidato a materia oscura y los últimos dos proponen un mecanismo para dar masa a al menos dos neutrinos. En todos los modelos hemos considerado la generación de la abudancia de materia oscura en un escenario de freeze-out y la partícula candidata a materia oscura será un escalar massivo debilmente interactuante (WIMP definido por su nombre en inglés). El primer trabajo está relacionado con estudiar las principales diferencias entre el Inert Higgs Doiblet Model and el Scotogenic Model. Hemos realizado un estudio profundo de la materia oscura en ambos, investigando puntos que sobrevivan a las cotas mas fuertes en física y en los actuales experimentos y también considerando que estos resultados pueden explicar la densidad de materia oscura en el Universo en su totalidad. Estudiando una señal específica en el Compact Linear Collider (CLIC), investigamos los parámetros que contribuirán a obtener diferentes valores para la sección eficaz en ambos modelos. En el segundo trabajo, hemos reexaminado el Singlet + Triplet Scotogenic Model el cual generaliza la idea introducida en el Scotogenic model simple, haciendo su fenomenología viable y mucho mas rica. Relalizamos un estudio fenomenológico detallado de la materia oscura escalar, actualizando las cotas actuales de los experimentos. Investigamos la detección directa de dark matter y la detección indirecta vía rayos gamma. Además, realizamos un estudio en colisionadores el cual tendrá relevantes implicaciones para las futuras búsquedas a alta luminosidad del Large Hadron Collider (LHC definido por su nombre en inglés).
Black holes in scale-dependent frameworks.
(2019) Rincón, Ángel; Koch, Benjamin; Pontificia Universidad Católica de Chile. Facultad de Física
In the present thesis, we investigate the scale–dependence of some well known black hole solutions in 2+1 dimensions at the level of the effective action in the presence of a cosmological constant or an electrical source. We promote the classical parameters of the theory, {G0,(· · ·)0}, to scale–dependent couplings, {Gk,(· · ·)k} and then we solve the corresponding effective Einstein field equations. To close the system of equations we impose the null energy condition. This last condition (valid in arbitrary dimension) provides a differential equation which, after solving it, allows to obtain in a simple way the specific form of the gravitational coupling. Furthermore, perfect-fluid like parameters are induced via the scale-dependent gravitational coupling. Finally, to exemplify the effect of the running of the couplings on the properties of the scale-dependent black hole solutions, we show a few concrete examples.In the present thesis, we investigate the scale–dependence of some well known black hole solutions in 2+1 dimensions at the level of the effective action in the presence of a cosmological constant or an electrical source. We promote the classical parameters of the theory, {G0,(· · ·)0}, to scale–dependent couplings, {Gk,(· · ·)k} and then we solve the corresponding effective Einstein field equations. To close the system of equations we impose the null energy condition. This last condition (valid in arbitrary dimension) provides a differential equation which, after solving it, allows to obtain in a simple way the specific form of the gravitational coupling. Furthermore, perfect-fluid like parameters are induced via the scale-dependent gravitational coupling. Finally, to exemplify the effect of the running of the couplings on the properties of the scale-dependent black hole solutions, we show a few concrete examples.In the present thesis, we investigate the scale–dependence of some well known black hole solutions in 2+1 dimensions at the level of the effective action in the presence of a cosmological constant or an electrical source. We promote the classical parameters of the theory, {G0,(· · ·)0}, to scale–dependent couplings, {Gk,(· · ·)k} and then we solve the corresponding effective Einstein field equations. To close the system of equations we impose the null energy condition. This last condition (valid in arbitrary dimension) provides a differential equation which, after solving it, allows to obtain in a simple way the specific form of the gravitational coupling. Furthermore, perfect-fluid like parameters are induced via the scale-dependent gravitational coupling. Finally, to exemplify the effect of the running of the couplings on the properties of the scale-dependent black hole solutions, we show a few concrete examples.In the present thesis, we investigate the scale–dependence of some well known black hole solutions in 2+1 dimensions at the level of the effective action in the presence of a cosmological constant or an electrical source. We promote the classical parameters of the theory, {G0,(· · ·)0}, to scale–dependent couplings, {Gk,(· · ·)k} and then we solve the corresponding effective Einstein field equations. To close the system of equations we impose the null energy condition. This last condition (valid in arbitrary dimension) provides a differential equation which, after solving it, allows to obtain in a simple way the specific form of the gravitational coupling. Furthermore, perfect-fluid like parameters are induced via the scale-dependent gravitational coupling. Finally, to exemplify the effect of the running of the couplings on the properties of the scale-dependent black hole solutions, we show a few concrete examples.
Characterization of extragalactic fast X-ray transients from X-ray archival searches
(2023) Quirola Vasquez, Jonathan Alexander; Bauer, Franz Erik; Jonker, Peter; Pontificia Universidad Católica de Chile. Instituto de Astrofísica
Extragalactic fast X-ray transients (FXTs) are non-Galactic short flashes of X-ray photons (in the narrow range of ≈0.3–10 keV) of unclear origin that last a few minutes to hours. A variety of astronomical objects and physical mechanisms have been proposed for the origin of extragalactic FXTs, such as core-collapse SNe shock breakout (SBOs), gamma-ray bursts (GRBs), and intermediate massive black holes (IMBH)-white dwarf (WD) tidal disruption events. During the last two decades, several FXTs have been detected by Chandra, XMM-Newton, and Swift-XRT, serendipitously (for instance, Soderberg et al. 2008; Bauer et al. 2017; Xue et al. 2019; Alp & Larsson 2020; Lin et al. 2022). Previously, Yang et al. (2019) developed a method that can efficiently detect single X-ray burst light curves in a single Chandra exposure, and systematically applied it to ≈19 Ms Chandra. While this method efficiently detected all past known FXTs (2), it failed to find any new FXT candidates, setting loose bounds on their space densities. The main objective of this thesis is to identify and characterize extragalactic FXTs hidden in the Chandra archive. We apply here two modified versions of the algorithm developed by Yang et al. 2019 to X-ray sources located at |b|>10 deg (i.e., 14281 Chandra observations, totaling ≈258 Ms and 857 deg 2 ) to minimize stellar flares contamination. In Chapter 2, we consider the X-ray sources of the Chandra Source Catalog 2.0 (data available until the end of 2014; CSC2). In Chapter 3, we extend our systematic search by reprocessing the Chandra data not covered by CSC2. In both instances, we adopt additional criteria to rule out strong contamination from persistent X-ray sources (analyzing further X-ray observations taken by Chandra, XMM-Newton, Swift–XRT, Einstein, and ROSAT, and considering other astronomical catalogs such as Gaia, NED, SIMBAD, VHS, DES, Pan-STARRS), in order to identify 22 FXTs (14 and 8 FXTs identified inside CSC2 and beyond it, respectively) consistent with an extragalactic origin. We rediscover all previously reported Chandra events from the literature (Jonker et al. 2013; Glennie et al. 2015; Bauer et al. 2017; Xue et al. 2019; Lin et al. 2019, 2021, 2022). The 22 FXT candidates have peak 0.3–10 keV fluxes between F X,peak ≈6×10^−14 to 2×10^−10 erg cm−2 s−1 and T 90 durations from ≈0.3 to 40 ks. The sample is split into two groups: five "nearby" FXTs that occurred within d≲100 Mpc, and 17 "distant" FXTs at d>100 Mpc. Indeed, the latter have redshifts between ≈0.3 to 2.2. Thus, the local and distant samples have associated peak X-ray luminosities of L X,peak ≈10^39 − 10^40 and 10^44 − 10^47 erg s−1, respectively. After applying completeness corrections, we calculate the first FXT X-ray luminosity function and derive event rates for the nearby and distant samples of 34.3_{−10.8}^{+13.7} and 36.9_{−8.3}^{+9.7} deg-2 yr−1, respectively, for a limiting flux of Fpeak=10^−13 erg cm−2 s−1. We compare the volumetric density rate of FXTs with well-known transient classes such as SBOs, GRBs, and TDEs, concluding that FXTs remain broadly consistent with different transients at distinct cosmic epochs. Regarding their host properties, local hosts tend to lie just below the star-forming main sequence, with many FXTs situated in or near HII regions, implying some relation to massive stars. On the other hand, distant hosts tend to be spread all over (starburst, main sequence, and green valley regions), potentially consistent with GRB and SNe hosts. Timing and spectral properties, combined with other properties such as galactic parameters and volumetric rates, might imply that we have a mix of origins related to this novel sample of FXTs. Finally, in Chapter 4 we interpret a subset of nine FXTs with plateau or fast-rise light curves in the context of an X-ray magnetar model produced after the merger of two neutron stars. The model produces good fits to the light curves of this sub-sample, and the best-fit magnetar parameters suggest a common origin. Although the interpretation is consistent with most of the observational parameters, exploring other scenarios remains a necessary future task.
Chemistry in externally FUV illuminated protoplanetary disks in the Orion Nebula Cluster
(2022) Díaz Berríos, Javiera Katalina; Guzmán Veloso, Viviana; Pontificia Universidad Católica de Chile. Facultad de Física
Understanding the chemical composition and distribution of the birthplaces of planets (protoplanetary disks) is key to constraining the initial conditions of planet formation and planetary atmospheres. Most protoplanetary disks are born in stellar clusters and can therefore be affected by the radiation of nearby massive stars. However, little is known about the potential differences or similarities in the chemistry of isolated versus externally irradiated disks. Motivated by this question, we present ALMA Band 6 observations of two protoplanetary disks in the outskirts of the Orion Nebula Cluster (ONC) to explore the chemical composition of disks exposed to (external) FUV radiation fields: the large 216–0939 disk and the binary system 253–1536A/B. We successfully detect lines from CO isotopologues, HCN, H2CO, and C2H toward both protoplanetary disks. Undetected molecular lines include DCN and C3H2. Based on the observed disk–integrated line fluxes and flux, we do not find significant differences between isolated and irradiated disks. This suggests that these sources are far enough from the ONC so that their chemistry is not affected by the external radiation field or that we are observing the region from the disk that survives the external radiation; Indeed, these disks are massive and could, therefore self–shield from the radiation field. However, we expect CN emission to be brighter in irradiated disks than in isolated ones, which can be tested with future ALMA observations. We also expect stronger differences for disks that are closer to the ONC.
Contrasting neutron star heating mechanisms with Hubble Space Telescope observations
(2018) Rodríguez Tapia, Luis; Reisenegger, Andreas; Pontificia Universidad Católica de Chile. Instituto de Física
Si las estrellas de neutrones se enfriaran pasivamente, se esperaría que se vuelvan indetectables en un tiempo menor a 107 años, al alcanzar bajas temperaturas T < 104 K. Sin embargo, radiación del tipo ultravioleta, que implica temperaturas superficiales T ∼ 105 K, fue detectada desde los pulsares de Giga años PSR J0437- 4715 y PSR J2124-3358 y también desde el pulsar B0950+08 cuya edad es ∼ 107 años. Esta discrepancia puede ser explicada por un grupo de mecanismos de calentamiento propuestos en la literatura. Usando el código de Petrovich y Reisenegger se calcularon curvas de evolución térmica considerando diferentes mecanismos de calentamiento. Estas fueron contrastadas con las temperaturas inferidas a partir de las observaciones de los pulsares para determinar cuál es la principal fuente de emisión térmica de las estrellas de neutrones. Encontramos que el calentamiento rotoquímico, reacciones nucleares en las capas profundas de la corteza y el calor liberado por la fricción de vórtices superfluidos pueden mantener la estrella lo suficientemente caliente más allá del tiempo estándar de enfriamiento pasivo y explicar las observaciones.Si las estrellas de neutrones se enfriaran pasivamente, se esperaría que se vuelvan indetectables en un tiempo menor a 107 años, al alcanzar bajas temperaturas T < 104 K. Sin embargo, radiación del tipo ultravioleta, que implica temperaturas superficiales T ∼ 105 K, fue detectada desde los pulsares de Giga años PSR J0437- 4715 y PSR J2124-3358 y también desde el pulsar B0950+08 cuya edad es ∼ 107 años. Esta discrepancia puede ser explicada por un grupo de mecanismos de calentamiento propuestos en la literatura. Usando el código de Petrovich y Reisenegger se calcularon curvas de evolución térmica considerando diferentes mecanismos de calentamiento. Estas fueron contrastadas con las temperaturas inferidas a partir de las observaciones de los pulsares para determinar cuál es la principal fuente de emisión térmica de las estrellas de neutrones. Encontramos que el calentamiento rotoquímico, reacciones nucleares en las capas profundas de la corteza y el calor liberado por la fricción de vórtices superfluidos pueden mantener la estrella lo suficientemente caliente más allá del tiempo estándar de enfriamiento pasivo y explicar las observaciones.
Evolution of Chemical Patterns During Major Mergers
(2025) Jara Ferreira, Francisco Eduardo; Tissera, Patricia; Pontificia Universidad Católica de Chile. Instituto de Astrofísica
El estudio de la evolución química de las galaxias es clave para comprender su formación y desarrollo, especialmente en fusiones e interacciones. Estas afectan la composición química y estructura de las galaxias al inducir flujos de gas, estallidos de formación estelar y redistribución de elementos. En esta tesis, se analizan las poblaciones estelares en 12 simulaciones no cosmológicas con el código P-Gadget3, explorando diferentes modelos de Delay Time Distribution (DTD) para supernovas tipo Ia y condiciones iniciales (galaxias aisladas con y sin barra y una fusión masiva).El análisis del plano [Fe/H]–[O/Fe] revela una doble trayectoria en las simulaciones de galaxias fusionando, con loops formados en la interacción y en episodios tardíos de formación estelar. Los modelos DTD correspondientes a SD, DD y Pritchet muestran una evolución química más dinámica, mientras que el modelo Bimodal atenúa los loops. Adicionalmente, hemos probado métodos analíticos y filogenéticos para identificar huellas químicas de fusiones masivas, encontrando diferencias claras entre galaxias aisladas y fusionadas. Estos resultados sugieren la existencia de patrones químicos característicos de galaxias que han pasado por una fusión masiva, abriendo la posibilidad de la aplicación de este análisis en observaciones y simulaciones que incluyan cosmología.
High-Cadence Stellar Variability Studies of Galactic RR Lyrae Stars with DECam
(2023) Baeza Villagra, Karina; Catelan, Márcio; Pontificia Universidad Católica de Chile. Facultad de Física
As part of the DECam Alliance for Transients (DECAT), a consortium of time- domain DECam programs, the DECam Deep Drilling Program (DDP) is being conducted at the Blanco 4m telescope, located at Cerro Tololo Inter-American Observatory, Chile. The DDP includes the DECaPS East field, situated in the Galactic bulge at coordinates (RA, DEC)(J2000) = (18:03:34, -29:32:02). We performed two nights of high-cadence, multi- band (griz) observations utilizing DECam. We obtained high-quality griz light curves for 1033 previously identified RR Lyrae stars. Subsequently, a robust Fourier decomposition analysis was con- ducted, generating well-defined, multi-band light curve templates for 143 RRab and 146 RRc stars. This process aimed to update and enhance the existing RR Lyrae star templates catalog. Therefore, our work is expected to broadly apply to the data acquired from the Vera C. Rubin Observatory’s Legacy Survey of Space and Time. Furthermore, we compared and analyzed the dependence of Fourier coef- ficients and other derived light curve parameters on the effective wavelength, providing valuable in-sights into the behavior and structure of RR Lyrae stars. Another significant contribution of this study was the construction of the Period- φ31-[Fe/H] relations, total-to-selective extinction ratios, and distances for each star in both the DECam and Sloan photometric systems. This information is crucial for investigating RR Lyrae stars and their role as tracers of Galactic structures. By combining these results, we better un- derstand the characteristics and morphology of their light curves, the chemical composition through studying their metallicities, and the spatial distribution of RR Lyrae stars within the Galactic bulge. This knowledge contributes to the overall effort of classifying and detecting variable stars.
Lepton universality in the MSSM with trilinear R-parity violation model
(2024) Guirriman Alvarez, Alexis Vladimir; Díaz Gutiérrez, Marco Aurelio; Pontificia Universidad Católica de Chile. Facultad de Física
The Standard Model (SM) of particle physics, though highly successful, fails to address several fundamental questions, including the neutrino masses origin, the nature of dark matter, among others. The recent LHCb collaboration analysis measured the ratio of branching fractions RK inB+ → K+ℓ+ℓ− decay to test lepton universality, a property predicted by the SM. This observable is particularly powerful due to the cancellation of hadronic uncertainties, making it a sensitive probe for new physics. The measured value of RK is consistent with the SM prediction, suggesting nosignificant lepton universality violation. Nevertheless, given the limitations of the SM, this thesis explores a SM extension using the MSSM+λ ′TRPV model. By incorporating all possible SUSY contributions, we aim to theoretically predict the experimental RK result, providing a novel perspective on determining the parameter space that fit with the experimental measurement. The analysis is conducted within an Effective Field Theory framework across four different scenarios for Wilson Coefficients to account for the higher energy scales associated with these particles, translating their effects to the measurable energy range. The theoretical calculation is performedusing a scan in Python, while respecting other experimental constraints regarding SUSY particles. We found that the parameter space that respect the 3σ region of the LHCb collaboration measurement is |λ′| ≲ 10−2 or m˜ ≳ 8.5 TeV. Additionally, we found that our result is independent from each scenario for Wilson Coefficients. Finally, we discovered that RK has no particular bias towards any individual λ′ijk.
Magneto-thermal evolution of neutron star cores in the “strong-coupling regime”
(2020) Moraga Vent, Nicolás Andrés; Reisenegger, Andreas; Pontificia Universidad Católica de Chile. Instituto de Física
In this thesis we study a young neutron star, with internal temperatures T >10^9 K, where the particles in the core are strongly coupled by collisional forces and can convert into each other by beta decays, in the so called ``strong-coupling regime``. At this stage, the magnetic field induces small fluid displacements, changing the local chemical composition and generating pressure gradient forces, which tend to be erased by beta decays. Depending on the strength of the chemical departure, this reactions can lead to a non-trivial thermal evolution as a consequence of the magnetic feedback. This mechanism converts magneticto thermal energy and could explain the high surface luminosity of magnetars (highly magnetize neutron stars). In this thesis, we present the first long-term magneto-thermal simulation of a neutron star core in this regime. We concluded that, for internal magnetic field strength field B > 10^16 G, the possibility of a magnetic feedback due to the chemical departure is not possible because it would occur when the ambipolar heating (friction between charged particles and neutrons) is more likely to heat the core.
Metallicities and ages in the red sequence of two clusters of galaxies
(2022) Muñoz López, Constanza Betzabé; Barrientos, Luis Felipe; Pontificia Universidad Católica de Chile. Facultad de Física
Esta tesis se centra principalmente en las propiedades de las galaxias de secuencia roja y qué pueden decirnos estos parámetros acerca de las características y los procesos de formación de las galaxias. Las galaxias de tipo temprano (early-type) ofrecen la oportunidad de estudiar la formación y evolución de poblaciones estelares. Mediante el uso de fotometría proveniente del HST y datos espectroscópicos telescopio VLT/MUSE de dos cúmulos de galaxias, ha sido posible analizar edades y metalicidades de las galaxias y compararlas con otros observables. Se creó un modelo de secuencia roja para ambos cúmulos y se estableció una conexión entre las edades de las galaxias y sus respectivo desplazamiento con la secuencia roja. Las observaciones de este trabajo sugieren que la mayoría de las galaxias comenzaron a formar sus poblaciones estelares cuando el Universo era joven (z> 3) y que ya tenían acumulada más del 80% de su masa a z = 2. Sin embargo, no contamos con la sensibilidad suficiente para establecer el momento exacto en que comenzaron los procesos de formación estelar.
New insights and methods for the clustering of emission line galaxies.
(2019) Jiménez Henríquez, Esteban; Padilla, Nelson; Pontificia Universidad Católica de Chile. Instituto de Astrofísica
We study the dependence of emission line galaxies (ELG) clustering in halo properties besides mass, an effect known as assembly bias (AB). This AB signature is scale-dependent in some ELG samples and may contribute with potential systematic effects on cosmology constraints. We test different implementations of the halo occupation distribution (HOD) model to construct mock galaxy catalogues that mimic ELG selected samples produced by a semi-analytical model (SAM). These catalogues are useful to understand the future observational samples. We select galaxies from two different SAMs, applied to the Millennium-WMAP7 and the MultiDark Plank 2 simulation. We use fixed number density galaxy samples selected according to stellar mass, star formation rate (SFR), and emission line luminosity from Hα, [OIII]λ5007, and [OII]λλ3727 − 3729 emission, obtained from a photoionization code. We develop three different schemes to populate haloes with galaxies with increasing complexity, considering the scatter of the satellites HOD as an additional parameter in the modellings. The quality of the HOD modelling is determined by comparing the two-point correlation function (2PCF) of the HOD mocks and the SAM samples. The HOD modelling that uses the HOD of centrals and satellites separately, and assume a negative binomial distribution for the satellite HOD, produce the best clustering predictions. The scatter in the satellites HOD is a key consideration for HOD mock catalogues that mimic ELG selected samples in future galaxy surveys. The origin of the scale-dependent AB seems to be related to an environment selection effect rather than a physical reason. We found that galaxies in underdense regions and low gas metallicity, make the main contribution to the scale-dependent signature. We obtain that the peak of the Baryon Acoustic Oscillation (BAO) for some ELG samples is in lower scales than expected, and the β parameter is non-constant in large scales. Hence, this selection effect can introduce systematic in the inferred cosmology from ELGs.
Structure of the obscured galactic disk with pulsating variables.
(2019) Hajdu, Gergely; Catelan, Márcio; Pontificia Universidad Católica de Chile. Instituto de Astrofísica
Las estrellas variables pulsantes brillantes, tales como Cefeidas y RR-Lyras, son sondas fundamentales de la estructura de las componentes vieja y joven de la Vía Láctea. Sin embargo, el lado más alejado del disco de la Galaxia aún no ha sido mapeado usando tales variables debido a la severa extinción causada por polvo interestelar en frente de ellas. En esta tesis, las curvas de luz en infrarrojo cercano de la muestra VISTA Variables in the Vía Láctea son utilizadas para penetrar esas regiones y descubrir miles de Cefeidas o RR Lyras previamente “escondidas”. El análisis de las curvas de luz de las variables RR Lyras fue ejecutado con un algoritmo de ajuste, y sus metalicidades determinadas de siluetas de sus curvas de luz en el infrarrojo cercano usando métodos recientemente desarrollados. Estas abundancias fotométricas de metales, con sus posiciones en el disco Galáctico, apoyan las teorílas de la formación de adentro hacia fuera del disco de la Galaxia. Las Cefeidas descubiertas fueron clasificadas en los subtipos viejo (Tipo II) y nuevo (Clásicas). Una nueva ley de extinción en el infrarrojo cercano fue determinada usando Cefeidas Tipo II, utilizando su concentración en el centro Galáctico. La distribución de las Cefeidas Clásicas en el disco Galáctico sigue el pandeo Galáctico y el ensanchamiento del disco de la Galaxia en grandes radios Galactocéntricos. Un primer intento se efectuó con el fin de conectar las ubicaciones actuales de las Cefeidas Clásicas con la estructura de brazos espirales de la Vía Láctea.
Thermodynamics of graviton condensate and the Kiselev black hole
(2020) Mancilla Pérez, Robinson Humberto; Alfaro Solís, Jorge Luis; Pontificia Universidad Católica de Chile. Instituto de Física
In this thesis, we will present the thermodynamic study of a model that considers the black hole as a condensation of gravitons (55) (56). We will obtain a correction to the Hawking temperature and a negative pressure for a black hole of mass M. In this way, the graviton condensate, which is assumed to be at the critical point defined by the condition µch=0, will have well-defined thermodynamic quantities P, V , Th, S, and U as any other Bose-Einstein condensate. We will also discuss the Kiselev black hole, which has the capacity to parametrize the most well-known spherically symmetric black holes. We will show that this is true, even at the thermodynamic level. Finally, we will present a new metric, which we will call the BEC-Kiselev black hole, that will allow us to extend the graviton condensate to the case of solutions with different types of the energy-momentum tensor.In this thesis, we will present the thermodynamic study of a model that considers the black hole as a condensation of gravitons (55) (56). We will obtain a correction to the Hawking temperature and a negative pressure for a black hole of mass M. In this way, the graviton condensate, which is assumed to be at the critical point defined by the condition µch=0, will have well-defined thermodynamic quantities P, V , Th, S, and U as any other Bose-Einstein condensate. We will also discuss the Kiselev black hole, which has the capacity to parametrize the most well-known spherically symmetric black holes. We will show that this is true, even at the thermodynamic level. Finally, we will present a new metric, which we will call the BEC-Kiselev black hole, that will allow us to extend the graviton condensate to the case of solutions with different types of the energy-momentum tensor.In this thesis, we will present the thermodynamic study of a model that considers the black hole as a condensation of gravitons (55) (56). We will obtain a correction to the Hawking temperature and a negative pressure for a black hole of mass M. In this way, the graviton condensate, which is assumed to be at the critical point defined by the condition µch=0, will have well-defined thermodynamic quantities P, V , Th, S, and U as any other Bose-Einstein condensate. We will also discuss the Kiselev black hole, which has the capacity to parametrize the most well-known spherically symmetric black holes. We will show that this is true, even at the thermodynamic level. Finally, we will present a new metric, which we will call the BEC-Kiselev black hole, that will allow us to extend the graviton condensate to the case of solutions with different types of the energy-momentum tensor.In this thesis, we will present the thermodynamic study of a model that considers the black hole as a condensation of gravitons (55) (56). We will obtain a correction to the Hawking temperature and a negative pressure for a black hole of mass M. In this way, the graviton condensate, which is assumed to be at the critical point defined by the condition µch=0, will have well-defined thermodynamic quantities P, V , Th, S, and U as any other Bose-Einstein condensate. We will also discuss the Kiselev black hole, which has the capacity to parametrize the most well-known spherically symmetric black holes. We will show that this is true, even at the thermodynamic level. Finally, we will present a new metric, which we will call the BEC-Kiselev black hole, that will allow us to extend the graviton condensate to the case of solutions with different types of the energy-momentum tensor.In this thesis, we will present the thermodynamic study of a model that considers the black hole as a condensation of gravitons (55) (56). We will obtain a correction to the Hawking temperature and a negative pressure for a black hole of mass M. In this way, the graviton condensate, which is assumed to be at the critical point defined by the condition µch=0, will have well-defined thermodynamic quantities P, V , Th, S, and U as any other Bose-Einstein condensate. We will also discuss the Kiselev black hole, which has the capacity to parametrize the most well-known spherically symmetric black holes. We will show that this is true, even at the thermodynamic level. Finally, we will present a new metric, which we will call the BEC-Kiselev black hole, that will allow us to extend the graviton condensate to the case of solutions with different types of the energy-momentum tensor.In this thesis, we will present the thermodynamic study of a model that considers the black hole as a condensation of gravitons (55) (56). We will obtain a correction to the Hawking temperature and a negative pressure for a black hole of mass M. In this way, the graviton condensate, which is assumed to be at the critical point defined by the condition µch=0, will have well-defined thermodynamic quantities P, V , Th, S, and U as any other Bose-Einstein condensate. We will also discuss the Kiselev black hole, which has the capacity to parametrize the most well-known spherically symmetric black holes. We will show that this is true, even at the thermodynamic level. Finally, we will present a new metric, which we will call the BEC-Kiselev black hole, that will allow us to extend the graviton condensate to the case of solutions with different types of the energy-momentum tensor.In this thesis, we will present the thermodynamic study of a model that considers the black hole as a condensation of gravitons (55) (56). We will obtain a correction to the Hawking temperature and a negative pressure for a black hole of mass M. In this way, the graviton condensate, which is assumed to be at the critical point defined by the condition µch=0, will have well-defined thermodynamic quantities P, V , Th, S, and U as any other Bose-Einstein condensate. We will also discuss the Kiselev black hole, which has the capacity to parametrize the most well-known spherically symmetric black holes. We will show that this is true, even at the thermodynamic level. Finally, we will present a new metric, which we will call the BEC-Kiselev black hole, that will allow us to extend the graviton condensate to the case of solutions with different types of the energy-momentum tensor.In this thesis, we will present the thermodynamic study of a model that considers the black hole as a condensation of gravitons (55) (56). We will obtain a correction to the Hawking temperature and a negative pressure for a black hole of mass M. In this way, the graviton condensate, which is assumed to be at the critical point defined by the condition µch=0, will have well-defined thermodynamic quantities P, V , Th, S, and U as any other Bose-Einstein condensate. We will also discuss the Kiselev black hole, which has the capacity to parametrize the most well-known spherically symmetric black holes. We will show that this is true, even at the thermodynamic level. Finally, we will present a new metric, which we will call the BEC-Kiselev black hole, that will allow us to extend the graviton condensate to the case of solutions with different types of the energy-momentum tensor.In this thesis, we will present the thermodynamic study of a model that considers the black hole as a condensation of gravitons (55) (56). We will obtain a correction to the Hawking temperature and a negative pressure for a black hole of mass M. In this way, the graviton condensate, which is assumed to be at the critical point defined by the condition µch=0, will have well-defined thermodynamic quantities P, V , Th, S, and U as any other Bose-Einstein condensate. We will also discuss the Kiselev black hole, which has the capacity to parametrize the most well-known spherically symmetric black holes. We will show that this is true, even at the thermodynamic level. Finally, we will present a new metric, which we will call the BEC-Kiselev black hole, that will allow us to extend the graviton condensate to the case of solutions with different types of the energy-momentum tensor.In this thesis, we will present the thermodynamic study of a model that considers the black hole as a condensation of gravitons (55) (56). We will obtain a correction to the Hawking temperature and a negative pressure for a black hole of mass M. In this way, the graviton condensate, which is assumed to be at the critical point defined by the condition µch=0, will have well-defined thermodynamic quantities P, V , Th, S, and U as any other Bose-Einstein condensate. We will also discuss the Kiselev black hole, which has the capacity to parametrize the most well-known spherically symmetric black holes. We will show that this is true, even at the thermodynamic level. Finally, we will present a new metric, which we will call the BEC-Kiselev black hole, that will allow us to extend the graviton condensate to the case of solutions with different types of the energy-momentum tensor.
Unveiling the architecture of the Fornax galaxy cluster with its different stellar systems
(2018) Órdenes Briceño, Yasna; Puzia, Thomas H.; Grebel, Eva K.; Pontificia Universidad Católica de Chile. Facultad de Física
A crucial question in astronomy is how galaxies assemble their mass over cosmic time. In this thesis, we focus on the Fornax Galaxy Cluster as a laboratory to study galaxy evolution processes, as it is the second closest galaxy cluster which allows a detailed view of its cluster members. It hosts a variety of stellar systems from giant galaxies to dwarf galaxies and more compact and dense ones such as globular clusters and ultra-compact dwarf galaxies which we call compact stellar systems (CSSs). We use data from the Next Generation Fornax Survey (NGFS) with optical imaging obtained with the Dark Energy Camera (DECam) mounted at Blanco/CTIO and near-infrared data obtained with VIRCam at VISTA/ESO. This data provides deep and homogeneous photometry in u'g'i' JKs spatially covering the Fornax cluster out to half its virial radius. We investigate the properties of nucleated dwarf galaxies and compact stellar systems in the Fornax core region (r < 0.25rvir). Furthermore, we study the dwarf galaxy population with MB > −16 in the outer region of Fornax at radii of 0.25 < r/rvir < 0.5. The main results of this thesis are as follows: (1) We have discovered 271 previously undetected dwarf galaxies in the outer Fornax cluster region, increasing the total Fornax dwarf galaxy population from NGFS and other catalogs to a total number of 643 dwarfs with 181 being nucleated. (2) The study of 61 nuclear star clusters in dwarf galaxies showed that the nuclei have a bimodal mass distribution and that the scaling relation between nucleus mass and host galaxy mass holds for dwarf galaxies but at a less steep slope compared to brighter galaxies. The mass ratio Mnuc/Mgal shows a clear anticorrelation with Mgal for the lowest masses, reaching up to 10%. (3) A total of 1666 CSS candidates have been studied in the core region of Fornax, being the most clean photometrically selected sample using support vector machine techniques. Age, metallicity and mass were estimated for each CSS. A division of the properties in subgroups showed that the metal poor and old CSSs are sparsely distributed, intermediate metallicity and young CSSs are preferentially located along the East-West direction of Fornax centered in NGC 1399 and the most metal rich CSSs are concentrated in the vicinity of NGC 1399 and around the brightest galaxies. These different distributions for the metallicity and age subgroups allow us to constrain the mass assembly history of the Fornax Cluster. (4) Besides the Fornax cluster, we also discover five very diverse dwarf galaxies in another region of the sky, i.e. Hickson Compact Group 90 (HCG 90). Two of these dwarfs are a dwarf galaxy pair and one is a nucleated dwarf galaxy. According to their luminosity and structural parameters, they are similar to the dwarf galaxies we found in Fornax.

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