Дисертації з теми "Galactic formation"
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Peschken, Nicolas. "Formation and evolution of galactic discs." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4732/document.
Повний текст джерелаThis thesis explores the formation, evolution and structure of spiral galaxies using simulations, with an emphasis on the disc component. It is based on our N-body/SPH simulations involving a major merger between two disc galaxies at high redshift, both in possession of a hot gaseous halo. The discs of the progenitors are destroyed by the merger, and a well-extended disc forms in the remnant galaxy from newly born stars, star formation being fuelled by the gaseous halo. By the end of the simulation, the remnant galaxy shows all the properties of a spiral galaxy, proving for the first time in simulations how a late-type galaxy can be created from a major merger.In this thesis, several properties of the remnant galaxy are analysed, such as the stellar migration, the bar pattern speed, and the surface density radial profiles. This last point in particular represents a significant part of my work, using fits of the profiles to obtain the characteristic parameters of the disc. Our discs show a type II profile (downbending truncation), so that we can derive their scalelengths and truncation radius. The goal is to understand what determines the values of these parameters (which are very different from one simulation to another), as well as the origin of this specific profile. Finally, some type III discs (upbending truncation) obtained for simulations of isolated galaxies are presented and analysed, in order to investigate their formation mechanism
Puxley, Philip John. "Vigorous star formation in galactic nuclei." Thesis, University of Edinburgh, 1989. http://hdl.handle.net/1842/27222.
Повний текст джерелаBarnes, A. T. "A comparison of star formation within the galactic centre and galactic disc." Thesis, Liverpool John Moores University, 2018. http://researchonline.ljmu.ac.uk/8633/.
Повний текст джерелаHaehnelt, Martin. "Quasars and the formation of galactic nuclei." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319491.
Повний текст джерелаBrown, Richard Joseph Norman. "The formation and evolution of elliptical galaxies." Thesis, University of Birmingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273922.
Повний текст джерелаQuinn, Lyshia Jane. "Maser hunting in the galactic plane." Thesis, University of Manchester, 2010. https://www.research.manchester.ac.uk/portal/en/theses/maser-hunting-in-the-galactic-plane(efee9222-ec4e-4153-aa6a-4047c08430f9).html.
Повний текст джерелаSmilgys, Romas. "Formation of stars and stellar clusters in galactic environment." Thesis, University of St Andrews, 2018. http://hdl.handle.net/10023/13229.
Повний текст джерелаBailin, Jeremy. "Alignment of galactic components in models of galaxy formation." Diss., The University of Arizona, 2004. http://hdl.handle.net/10150/280672.
Повний текст джерелаRenda, Agostino. "The formation of stellar halos in late-type galaxies." Swinburne Research Bank, 2007. http://hdl.handle.net/1959.3/34778.
Повний текст джерелаSubmitted for the degree of Doctor of Philosophy, Swinburne University of Technology - 2007. Typescript. "May 2007". Bibliography: p. 225-237.
Chamcham, Khalil. "The evolution of galactic discs with a star formation threshold." Thesis, University of Sussex, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262321.
Повний текст джерелаHarding, Paul. "The formation of the Galactic bulge and halo: Observational signatures." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/289743.
Повний текст джерелаShaw, Martin Anthony. "The luminosity distributions of edge-on spiral and lenticular galaxies." Thesis, University of Edinburgh, 1988. http://hdl.handle.net/1842/27372.
Повний текст джерелаMinchin, Nigel Robert. "Near-infrared imaging polarimetry of bipolar nebulae." Thesis, University of Hertfordshire, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293286.
Повний текст джерелаMiceli, Antonino. "LONEOS RR Lyrae stars as probes of galactic structure and formation /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/9722.
Повний текст джерелаFreundlich, Jonathan. "Star formation across cosmic time and its influence on galactic dynamics." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066459/document.
Повний текст джерелаObservations show that ten billion years ago, galaxies formed their stars at rates up to twenty times higher than now. As stars are formed from cold molecular gas, a high star formation rate means a significant gas supply, and galaxies near the peak epoch of star formation are indeed much more gas-rich than nearby galaxies. Is the decline of the star formation rate mostly driven by the diminishing cold gas reservoir, or are the star formation processes also qualitatively different earlier in the history of the Universe? Ten billion years ago, young galaxies were clumpy and prone to violent gravitational instabilities, which may have contributed to their high star formation rate. Stars indeed form within giant, gravitationally-bound molecular clouds. But the earliest phases of star formation are still poorly understood. Some scenarii suggest the importance of interstellar filamentary structures as a first step towards core and star formation. How would their filamentary geometry affect pre-stellar cores? Feedback mechanisms related to stellar evolution also play an important role in regulating star formation, for example through powerful stellar winds and supernovae explosions which expel some of the gas and can even disturb the dark matter distribution in which each galaxy is assumed to be embedded. This PhD work focuses on three perspectives: (i) star formation near the peak epoch of star formation as seen from observations at sub-galactic scales; (ii) the formation of pre-stellar cores within the filamentary structures of the interstellar medium; and (iii) the effect of feedback processes resulting from star formation and evolution on the dark matter distribution
Moncelsi, Lorenzo. "BLAST : studying cosmic and Galactic star formation from a stratospheric balloon." Thesis, Cardiff University, 2011. http://orca.cf.ac.uk/13144/.
Повний текст джерелаRawlings, J. I. "Disentangling active galactic nuclei and star formation in extragalactic radio sources." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1425859/.
Повний текст джерелаUtreras, Contreras José. "Studyng the role of galactic rotation on star formation: numerical experiments." Tesis, Universidad de Chile, 2016. http://repositorio.uchile.cl/handle/2250/140026.
Повний текст джерелаEstudiamos la formación estelar y el rol de la rotación a escalas galácticas mediante simulaciones numéricas, utilizando el código de grillas adaptativas Enzo. Parte de este trabajo se centra en estudiar tres leyes de formación estelar encontradas en la literatura: las leyes de Kennicutt-Schmidt y Silk-Elmegreen, y la ecuación dimensionalmente homogénea propuesta por Escala (2015), las que relacionan la formación estelar proyectada con propiedades galácticas. Durante la última década, estudios con un mayor número de observaciones y mayor resolución espacial han puesto en duda que tan fidedignas son las leyes de Kennicutt-Schmidt y Silk-Elmegreen. Para la primera, estudios sugieren la existencia de dos regímenes formación estelar con diferente amplitud y otros proponen un único régimen modificando la forma funcional de la ley de Kennicutt-Schmidt original. Para la ley de Silk-Elmegreen grandes modificaciones no han sido requeridas, sin embargo estudios recientes del momento angular en galaxias han mostrado comportamientos contrarios a esta ley. Estos problemas han motivado el estudio del origen físico de estas relaciones y sus formulaciones matemáticas. Entre estos, Escala (2015) encuentra una función que es capaz de explicar varios observables (de observaciones y simulaciones), dependiendo de los procesos físicos que dominan la dinámica galáctica. En este trabajo estudiamos como las galaxias evolucionan comparándolas con estas leyes, mediante cambios en parámetros físicos, específicamente la rotación galáctica.\\ Realizamos simulaciones de galaxias espirales y discos nucleares de galaxias de formación violenta, constituidas por gas, estrellas y materia oscura. Durante la evolución de estas galaxias el gas puede enfriarse, fragmentarse y formar estrellas que interactúan con el medio interestelar mediante explosiones de supernova. Como condiciones iniciales, mantenemos fija la masa en gas y su distribución radial para cada tipo de galaxia mientras el perfil de rotación es variado. Esto nos permite aislar medianamente el efecto producido por la rotación en la evolución de las galaxias. Los parámetros deformación estelar son elegidos para obtener la bimodalidad observada en la ley de Kennicutt-Schmidt. La naturaleza bi-dimensional de esta ley nos motiva a estudiar las leyes mencionadas desde distintas líneas de visión, permitiéndonos probar como estas capturan la naturaleza tridimensional de la formación estelar. Nuestras simulaciones muestran ser bien representadas por las leyes de Kennicutt-Schmidt y Silk-Elmegreen globalmente. Sin embargo, encontramos una anti-correlación entre la eficiencia de formación estelar y la velocidad angular Ω, que no es considerada en estas leyes. Incluyendo los efectos de la inclinación respecto al observador, las simulaciones muestran menores tiempos de consumo de gas en la relación de Kennicutt-Schmidt y tiempos similares en la ley de Silk-Elmegreen, atribuido a efectos geométricos. La ecuación propuesta por Escala (2015) describe la evolución de las simulaciones con menor dispersión que las relaciones anteriores. Bajo esta formulación, diferentes inclinaciones muestran eficiencias similares, debido a que considera la concentración de gas en la línea de visión. Sin embargo, esta relación aún muestra la anti-correlación ya mencionada. Estudiamos esta anti-correlación y encontramos que la eficiencia de formación estelar decrece exponencialmente con la velocidad angular en ambos tipos de galaxia. Requiriendo que la eficiencia sea función de cantidades adimensionales, introducimos el parámetro de tiempo de caída libre inicial τ, encontrando que la eficiencia puede ser descrita por una función exponencial decreciente de Ωτ. Este resultado nos entrega una formación estelar que toma en cuenta la concentración de gas en la línea de visión y variaciones en la velocidad angular.
Westmoquette, M. S. "Super star clusters, their environment, and the formation of galactic winds." Thesis, University College London (University of London), 2007. http://discovery.ucl.ac.uk/1446265/.
Повний текст джерелаStonkutė, Edita. "Chemical composition of kinematically identified galactic stellar group." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2013. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2013~D_20130925_093107-33619.
Повний текст джерелаPaukščių Tako galaktikoje yra identifikuota žvaigždžių srautų, judančių bei kinematinių grupių, kurių kilmė siejama su įkritusiomis galaktikomis. Aktualu ištirti, ar yra tokių senųjų substruktūrų pėdsakų mūsų Saulės aplinkoje? Helmi ir kt. (2006), panaudoję Nordström ir kt. (2004) Ženevos–Kopenhagos apžvalgos (ŽKA) katalogą, identifikavo tris naujas koherentines žvaigždžių grupes, kurios pasižymi išskirtiniais kinematiniais parametrais ir gali būti užgalaktinės kilmės. Šiuo disertacijos darbu siekiama prisidėti prie Galaktikos substruktūrų tyrimų, nustatant detalią cheminę vienos iš Helmi ir kt. identifikuotų žvaigždžių grupių sudėtį. Svarbu išsiaiškinant, ar ŽKA kinematinės grupės žvaigždžių atmosferų cheminė sudėtis skiriasi nuo Galaktikos disko žvaigždžių. Nustatėme 21 3–osios ŽKA kinematinės grupės bei 6 palyginamųjų plonojo disko žvaigždžių atmosferų pagrindinius parametrus bei 22 cheminių elementų gausas. Kinematinės žvaigždžių grupės deguonies ir α–elementų gausos yra padidėjusios lyginant su plonuoju disku ir yra panašios į storojo disko. Cheminių elementų, daugiausia pagaminamų s–procese, gausos ir geležies grupės elementų gausos yra panašios į to paties metalingumo plonojo disko nykštukių cheminių elementų gausas, o cheminių elementų, daugiausia pagaminamų r–procese, gausos yra padidėjusios lyginant su plonuoju disku. Panaši cheminė tirtos kinematinės grupės bei storojo Galaktikos disko sudėtis rodo, kad kinematinės žvaigždžių grupės ir storojo disko žvaigždžių... [toliau žr. visą tekstą]
Marsden, Gaelen. "Observing the galactic plane with the Balloon-borne Large-Aperture Submillimeter Telescope." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/205.
Повний текст джерелаFalder, James Thomas. "The environments of high redshift active Galactic nuclei." Thesis, University of Hertfordshire, 2012. http://hdl.handle.net/2299/8960.
Повний текст джерелаAugustin, Ramona. "Characterising the circum-galactic medium : observations in absorption and simulations of emission." Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0254.
Повний текст джерелаUnderstanding the processes of gas flows in and out of galaxies is crucial in galaxy evolution studies. Yet, observations of the faint and diffuse Circum-Galactic Medium (CGM), where these processes take place, remain challenging. In this work, I explore different methods to observe, simulate and characterise the gas around galaxies in the CGM. I identified and characterised galaxy counterparts to Damped Lyman-alpha Absorbers (DLAs) at z equivalent 1 using highly spatially resolved Hubble Space Telescope (HST) observations. I determine their stellar masses and find that the galaxies are generally less massive than the average galaxy population, but follow the predicted trends in terms of star formation rate and metallicity. The high spatial resolution of the optical HST data also allows for a closer look at the morphology at those galaxies and reveals complex, unexpected structures. While absorption lets us investigate very faint gas, it is usually limited to a single line of sight and we need observations in emission to map the CGM and gain information on its extent and clumpiness. To improve observing strategies of the CGM in emission, I make predictions from dedicated cosmological zoom-in simulations, post-processed with a CLOUDY emission model. This combination allows to create mock IFU-like galaxy halo data cubes which are next used as input to instrument models in order to prepare CGM observations with FIREBall-2 (UV spectrograph on a balloon) and HARMONI (near-infrared IFU on the ELT). I predict that FIREBall-2 is capable of detecting Ly alpha and find HARMONI to be competitive for CGM studies
Iliev, Ilian Tzankov. "The equilibrium structure of cosmological halos and the effects of feedback on cosmological structure formation /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
Повний текст джерелаMajewski, Steven R., Ricardo P. Schiavon, Peter M. Frinchaboy, Carlos Allende Prieto, Robert Barkhouser, Dmitry Bizyaev, Basil Blank, et al. "The Apache Point Observatory Galactic Evolution Experiment (APOGEE)." IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/625493.
Повний текст джерелаRey, Raposo Ramon. "The interplay between stellar feedback and galactic environment in molecular clouds." Thesis, University of Exeter, 2015. http://hdl.handle.net/10871/21022.
Повний текст джерелаDuong, Ly. "Unravelling the evolution of the Galactic stellar disk and bulge." Phd thesis, Canberra, ACT : The Australian National University, 2018. http://hdl.handle.net/1885/149502.
Повний текст джерелаGreen, James Andrew. "Studying high-mass star formation & galactic structure through the methanol multibeam survey." Thesis, University of Manchester, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491493.
Повний текст джерелаBecerra, Saavedra Fernando Felipe. "A study of galactic star formation and massive black hole growth through simulations." Tesis, Universidad de Chile, 2012. http://www.repositorio.uchile.cl/handle/2250/112012.
Повний текст джерелаEstudiamos la formación estelar en escalas galácticas y el crecimiento de agujeros negros a través de simulaciones usando el código de grilla adaptativa de refinamiento Enzo. Nuestro estudio se centra en dos de las más famosas leyes de formación estelar: las ley de Kennicutt-Schmidt y la ley de Silk, ambas relacionan la tasa de formación estelar con propiedades globales de la galaxia. A pesar de que ambas han cuantificado exitosamente esta relación, aún no hay un consenso en el valor exacto de sus pendientes. Nosotros tratamos de clarificar este problema estudiando los factores que influyen en ambas leyes, tales como la densidad de gas superficial, el tiempo orbital y la masa rotacional. Para estudiar el crecimiento de agujeros negros masivos, centramos nuestro trabajo en las relaciones $M_{BH}-M_{bulge}$ y $M_{BH}-\sigma$, las cuales relacionan la masa de un agujero negro con propiedades globales de su galaxia huésped. Tratamos de explicar el origen de ambas relaciones a través de un análisis del Medio Interestelar. Modelamos galaxias locales con tres componentes: gas, estrellas y materia oscura. Dejamos a los modelos evolucionar por 1 Gyr, y durante la evolución el gas puede formar estrellas, las cuales mueren en forma de supernovas. Al final de las corridas, nuestras simulaciones están caracterizadas por un medio altamente turbulento y compresible, con una Función de Densidad de Probabilidades que puede ser ajustada por una distribución lognormal a altas densidades. Su espectro de potencia de velocidad es bien ajustado por una ley de potencia de pendiente ~-4 en el espacio k a escalas pequeñas, lo cual es más pronunciado que la turbulencia de Kolmogorov y la de Burger. Este espectro de potencia nos permite deducir una relación del tipo $v_r \sim v_{rot} \left( \lambda \over R_d \right)^{-\beta}$, la cual es el nexo necesario entre las propiedades globales de la galaxia y la alimentación del agujero negro masivo central. Estudiamos la eficiencia de formación estelar en nuestras galaxias, donde investigamos cómo la pendiente de las leyes de Kennicutt-Schmidt y Silk pueden variar dependiendo de cómo definamos las cantidades involucradas en ambas leyes. Las dos leyes son fuertemente dependientes en el criterio ocupado para seleccionar el radio al cual se calculan las densidades superficiales, y el intervalo de tiempo ocupado para medir la tasa de formación estelar. En el primer caso la elección de un radio más grande puede llevar a obtener menores pendientes, mientras que en el segundo caso las pendientes más bajas son obtenidas usando un intervalo de tiempo más grande para promediar las tasas de formación estelar. Ambos efectos pueden cambiar la pendiente de las leyes de formación estelar en el rango entre 0.8 y 2.1. Nuestras simulaciones también muestran una dependencia en los perfiles iniciales de $M_{rot}$. Esta relación es más pronunciada al comienzo de las simulaciones, donde la masa rotacional determina el tiempo al cual las galaxias comienzan a formar estrellas, y por lo tanto determina las tasas de formación estelar en etapas tempranas de la evolución.
Malefahlo, Eliab. "Measuring the quasar luminosity function below the detection threshold." University of the Western Cape, 2016. http://hdl.handle.net/11394/4956.
Повний текст джерелаThe radio emission of radio-quiet active galactic nuclei (AGN) is thought to be from star formation and AGN related emission. I investigate these sources using 1.4 GHz radio data from FIRST and three optical quasars samples from the SDSS: (i) a volume-limited sample in the redshift range 0:2 < z < 0:4 defined by Mi < -23 (ii) magnitude-limited sample in the redshift range 1:8 < z < 2:5 defined by mr ≤ 18:5 and (iii) a uniform sample in the redshift range 0:2 < z < 3:5 (divided into 12 redshift bins). I constructed radio source counts and radio luminosity functions (RLFs) using the optical quasars detected in FIRST, which are consistent with literature results obtained using SDSS and NVSS quasars. There are differences at the low uxs end because of the different resolutions of FIRST and NVSS. I applied a median stack method to the 12 redshift bins of the uniform sample and found that the median ux decreases from 182 µJy in the lowest redshift bin to 39 µJy and the highest redshift bin. This is because the high redshift quasars although more luminous than their low redshift counterparts, they are much further away so they have lower uxes. I probed the quasar radio source counts to lower levels using reconstructed source counts obtained by applying the Bayesian stack technique. The reconstructed radio source counts were then used to constructed the quasar RLF to lower levels, where I found: (i) for z < 1 the constructed quasar RLF has the same slope as the detected quasars, suggesting that like the detect quasars their radio emission is dominated by AGN related emission (ii) above z = 1 the constructed RLF steepens with redshift, which suggests the strong link between accretion rate and radio jet power is gradually breaking down towards faint optical luminosities at high redshift.
National Astrophysics and Space Science Program (NASSP) and SKA Africa
Xu, Lei. "The Relation between Luminous Active Nuclei and Star Formation in Their Host Galaxies." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/312746.
Повний текст джерелаNelson, Erica June. "The Spatial Distribution of Star Formation in Galaxies| Observing the Emergence of Galactic Structure." Thesis, Yale University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10160870.
Повний текст джерелаA high resolution measurement of the distribution of star formation within galaxies is key to understanding the emergence of galactic structure. The aim of this thesis is to understand how the structure of galaxies is built by developing a new method to spatially resolve their star formation. Using Ha maps for 2676 galaxies, this thesis shows where star formation is distributed in galaxies during the epoch 0.7 < z < 1.5 when a third of the total star formation in the history of the universe occurred. Across the star formation rate - stellar mass plane (the "main sequence"), star formation is `spatially coherent': in galaxies with higher than average star formation rates, Ha is enhanced throughout the disk; similarly, in galaxies with low star formation rates Ha is depressed throughout the disk. This places constraints both on the mechanisms for enhancing and quenching star formation as well as on how the structure of galaxies is built. The disk scale length of star formation in galaxies is larger than that of the stars, a direct demonstration that the disks of galaxies grow inside-out. While most star formation in most galaxies occurs in disks, not all of it does. With the first spatially resolved measurement of the Balmer decrement at z > 1, it can be seen that galaxies with M* > 1010M[special characters omitted] have significant dust attenuation toward their centers. This means that we are witnessing the build-up of the dense stellar cores of massive galaxies through dust-obscured in-situ star formation. The most massive galaxies are thought to have formed their dense stellar cores at even earlier cosmic epochs. This thesis presents the first confirmed example of a massive galaxy core in the process of formation at z = 2.3. It has one of the highest velocity dispersions ever measured for a normal star forming galaxy and also appears to be building through very dense, dust-enshrouded star formation.
Massari, Davide <1987>. "COSMIC-LAB: Terzan 5 as a fossil remnant of the Galactic bulge formation epoch." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amsdottorato.unibo.it/6731/1/Massari_Davide_tesi.pdf.
Повний текст джерелаMassari, Davide <1987>. "COSMIC-LAB: Terzan 5 as a fossil remnant of the Galactic bulge formation epoch." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amsdottorato.unibo.it/6731/.
Повний текст джерелаRagan, Sarah E. "Peering into the heart of galactic star formation : a detailed characterization of infrared-dark clouds /." [S.l. :] University of Michigan, 2009. http://adsabs.harvard.edu/abs/2009PhDT........12R.
Повний текст джерелаStanley, Flora. "Far-infrared constraints on the ongoing star formation of distant galaxies hosting active galactic nuclei." Thesis, Durham University, 2016. http://etheses.dur.ac.uk/11741/.
Повний текст джерелаSharma, Sanjib. "Numerical Simulations of Galaxy Formation: Angular Momentum Distribution and Phase Space Structure of Galactic Halos." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1413%5F1%5Fm.pdf&type=application/pdf.
Повний текст джерелаButterfield, Natalie. "Kinematics and evolution of massive star formation in the central molecular zone of the galactic center." Diss., University of Iowa, 2018. https://ir.uiowa.edu/etd/6382.
Повний текст джерелаSvoboda, Brian E., Yancy L. Shirley, Cara Battersby, Erik W. Rosolowsky, Adam G. Ginsburg, Timothy P. Ellsworth-Bowers, Michele R. Pestalozzi, et al. "THE BOLOCAM GALACTIC PLANE SURVEY. XIV. PHYSICAL PROPERTIES OF MASSIVE STARLESS AND STAR-FORMING CLUMPS." IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/621258.
Повний текст джерелаBallero, Silvia Kuna. "Evolution of chemical abundances in active and quiescent spiral bulges." Doctoral thesis, Università degli studi di Trieste, 2008. http://hdl.handle.net/10077/2560.
Повний текст джерелаIn this thesis I develop a chemical evolution model which takes advantage of the most recent high-quality abundance observations in the Galactic bulge to put constraints on its formation and evolution and to obtain a baseline model for bulges in general. I adopt updated massive star nucleosynthesis and follow the evolution of several alpha-elements and Fe by varying the evolutionary parameters. The [alpha/Fe] ratios in the bulge are correctly predicted to be supersolar for a wide range in [Fe/H], and the stellar metallicity distribution is reproduced assuming a short formation timescale, a high star formation efficiency and an initial mass function flatter than the disk. Metallicity-dependent oxygen yields with stellar mass loss are included in the chemical evolution models for the bulge and the solar neighbourhood. The agreement between predicted and observed [O/Mg] trends above solar metallicity is significantly improved; a normalisation problem probably indicates that the adopted semi-empirical yields need adjustment. The difference between [O/Fe] and the other [alpha/Fe] ratios in the bulge and solar neighbourhood is explained. I test the so-called universal initial mass function, suitable for ellipticals and disks, to see if the bulge stellar metallicity distribution can be reproduced by varying the yields for very massive stars, and included M31 in my analysis. I show that assuming a flatter initial mass function than the universal one is necessary, and that a variation exists in the initial mass function among different environments. Finally, I investigate the evolution of spiral bulges hosting Seyfert nuclei, with detailed calculations of the galactic potential and of the feedback from the central supermassive black hole in an Eddington-limited accretion regime. New spectro-photometrical evolution codes covering a wide range of stellar ages and metallicities allowed to model the photometric features of local bulges. I successfully predict the observed black hole-host bulge mass relation. The observed present-day nuclear bolometric luminosity is achieved only for the most massive bulges, otherwise a rejuvenation is necessary. The observed high star formation rates and metallicities, constancy of chemical abundances with the redshift and bulge present-day colours are reproduced, but a steeper initial mass function is required to match the colour-magnitude relation and the present K-band bulge luminosity.
In questa tesi, ho sviluppato un modello di evoluzione chimica che si avvale di recenti osservazioni ad alta qualità di abbondanze chimiche nel bulbo della Via Lattea, per porre dei vincoli sui suoi meccanismi di formazione ed evoluzione e ottenere un modello generale per i bulbi di spirale. Ho adottato una nucleosintesi aggiornata per le stelle massicce e seguito l'evoluzione di diversi elementi-alpha e del ferro, variando i parametri evolutivi. Si prevede correttamente che i rapporti [alpha/Fe] nel bulbo siano soprasolari per un ampio intervallo in [Fe/H]. La distribuzione in metallicità è riprodotta con un tempo di formazione breve, un'alta efficienza di formazione stellare e una funzione iniziale di massa più piatta che nel disco. Yields di ossigeno con perdita di massa stellare in funzione della metallicità sono stati inclusi nei modelli di evoluzione chimica del bulbo e dei dintorni solari. L'accordo tra gli andamenti di [O/Mg] previsti e osservati per metallicità soprasolari risulta sensibilmente migliorato; si spiega inoltre la differenza tra il rapporto [O/Fe] e gli altri [alpha/Fe] nel bulbo e nei dintorni solari. Un problema di normalizzazione indica che probabilmente gli yields semi-empirici adottati necessitano una revisione. Ho verificato se con la cosiddetta funzione iniziale di massa universale, adeguata per galassie ellittiche e dischi, la distribuzione in metallicità stellare del bulge può essere riprodotta calibrando gli yields delle stelle supermassicce, includendo M31 nell'analisi. Si dimostra che una funzione iniziale di massa più piatta di quella universale è necessaria, e che esiste una variazione nella funzione iniziale di massa tra i diversi ambienti. Infine, ho studiato l'evoluzione di bulbi di spirali che ospitano galassie di Seyfert, mediante calcoli dettagliati del potenziale galattico e del feedback dal buco nero supermassiccio centrale in un regime di accrescimento limitato dal tasso di Eddington. Nuovi codici spettro-fotometrici che coprono un ampio intervallo di età stellari e di metallicità hanno permesso di modellizzare le caratteristiche fotometriche dei bulbi locali. La relazione osservata tra massa del buco nero e del bulbo ospite è prevista con successo. La luminosità bolometrica nucleare misurata al tempo presente si consegue solo per i bulbi più massicci, negli altri casi è necessario un "ringiovanimento". Le osservazioni di alto tasso di formazione stellare, alte metallicità, invarianza di abbondanze chimiche col redshift e colori dei bulbi locali sono riprodotte; una funzione iniziale di massa più ripida è invece richiesta per la relazione colore-magnitudo e la luminosità dei bulbi in banda K al tempo presente.
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Draper, Aden R. "Understanding the connection between active galactic nuclei and host star formation through multi-wavelength population synthesis modeling." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45748.
Повний текст джерелаHayes, Christian R., Steven R. Majewski, Matthew Shetrone, Emma Fernández-Alvar, Carlos Allende Prieto, William J. Schuster, Leticia Carigi, et al. "Disentangling the Galactic Halo with APOGEE. I. Chemical and Kinematical Investigation of Distinct Metal-poor Populations." IOP PUBLISHING LTD, 2018. http://hdl.handle.net/10150/626539.
Повний текст джерелаLanger, Mathieu. "Origine du champ magnétique en cosmologie et formation des galaxies." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2002. http://tel.archives-ouvertes.fr/tel-00002495.
Повний текст джерелаLotz, Marcel [Verfasser], and Andreas [Akademischer Betreuer] Burkert. "Evolution of galactic star formation in galaxy clusters and post-starburst galaxies / Marcel Lotz ; Betreuer: Andreas Burkert." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2021. http://d-nb.info/1232176338/34.
Повний текст джерелаFeltre, Anna. "Multi-band Emission of Active Galactic Nuclei: the Relationship of Stellar and Gravitational-Accretion Activity." Doctoral thesis, Università degli studi di Padova, 2013. http://hdl.handle.net/11577/3423457.
Повний текст джерелаUna delle questioni ancora aperte nell'ambito dell'analisi dei nuclei galattici attivi riguarda il fatto che l'accrescimento gravitazionale nucleare è spesso accompagnato da una concomitante attività di formazione stellare . Qual è, in questo contesto, il ruolo assunto dalla polvere oscurante che circonda il nucleo e cosa può dirci lo stato dell'arte dei modelli a riguardo? Riescono i dati infrarossi dei satelliti Spitzer e Herschel a permettere uno studio approfondito di entrambi i fenomeni e, in tal caso, come e con quali limitazioni? La presenza di un nucleo attivo ha effettivamente un impatto sulle proprietà medio e lontano infrarosse delle galassie ospiti? Quali sono gli effetti della simultaneità dell'accrescimento gravitazionale nella regione nucleare e dell'attività di formazione stellare in queste stesse galassie? In questa Tesi viene esposto il nostro contributo al tentativo di rispondere a queste domande. Vengono presentati i risultati di uno studio comparativo tra diversi approcci usati per modellare i nuclei galattici attivi, focalizzandosi soprattutto sulla questione, attualmente ancora molto dibattuta, relativa alla morfologia della distribuzione della polvere nella struttura toroidale che circonda il centro del nucleo. Viene mostrato in maniera esaustiva che le proprietà della polvere dei nuclei attivi, ottenute dal confronto tra modelli e osservazioni (sia fotometria infrarossa a banda larga che spettro medio infrarosso), dipendono fortemente dalle assunzioni sulla distribuzione della polvere. Viene fornita, inoltre, una descrizione dettagliata della tecnica di sintesi spettrofotometrica sviluppata allo scopo di ricavare contemporaneamente le proprietà fisiche dei nuclei attivi a delle coesistenti galassie ''starburst''. Tale procedura è stata sviluppata per sfruttare al meglio le osservazioni medio e lontano infrarosse dei satelliti Spitzer e Herschel. In questo contesto, tali dati giocano un ruolo cruciale fornendo vincoli molto più forti sui modelli rispetto alle precedenti strutture osservative. Il codice di sintesi spettrofotometrica è stato usato su un vasto campione di sorgenti extragalattiche rappresentanti la popolazione della Herschel/Multi-tiered Extragalactic Survey per le quali erano disponibili sia lo spettro medio infrarosso di Spitzer che un pletora di dati multi-banda (SDSS, Spitzer e Herschel/SPIRE). L'obiettivo di tale lavoro è quello di studiare l'impatto che l'eventuale presenza di un nucleo attivo potrebbe avere sulle proprietà delle galassie ospiti. Infine, vengono presentati i principali risultati ottenuti, con particolare attenzione all'analisi del tasso di formazione stellare in relazione alla presenza di un nucleo attivo e al confronto delle proprietà della polvere calda, riscaldata dal nucleo attivo stesso, e fredda, riscaldata dalla formazione stellare.
Boissier, Samuel. "Formation Stellaire Aux Échelles Des Galaxies." Habilitation à diriger des recherches, Aix-Marseille Université, 2012. http://tel.archives-ouvertes.fr/tel-00761183.
Повний текст джерелаKordopatis, Georges. "Archéologie galactique : contraintes observationnelles aux modèles de formation du disque épais." Phd thesis, Observatoire de Paris, 2011. http://tel.archives-ouvertes.fr/tel-00736775.
Повний текст джерелаNormandeau, Magdalen. "The Galactic plane survey pilot project, the interstellar medium environment of the w3/w4/w5 star formation complex." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/nq20761.pdf.
Повний текст джерелаFukumura, Keigo. "Relativistic Accretion Flows onto Supermassive Black Holes: Shock Formation and Iron Fluorescent Emission Lines in Active Galactic Nuclei." Thesis, Montana State University, 2005. http://etd.lib.montana.edu/etd/2005/fukumura/FukumuraK0505.pdf.
Повний текст джерелаTalia, Margherita <1983>. "The Universe 10 Billion years ago: Morphologies, Star-formation rates and Galactic-scale winds in z ∼ 2 Galaxies." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5206/1/TALIA_MARGHERITA_tesi.pdf.
Повний текст джерела