Les galaxies passives présentent des morphologies et propriétés structurelles différentes des galaxies de masse similaire formant des étoiles. La preuve d'une distribution bimodale dans propriétés des galaxies suggère un lien entre les processus de quenching et les structures des galaxies. Contraindre les mécanismes et la chronologie de la formation du bulbe s'avère fondamental pour comprendre l'origine de cette corrélation. Les bulbes grossissent-ils au cours de la séquence principale? Les galaxies ré-accrètent-elles un disque formant des étoiles? Les galaxies stoppent-elles leur formation d'étoile à partir des régions internes? etc. Répondre de manière pertinente à ces questions nécessite de résoudre les parties internes des galaxies à différentes époques. Grâce aux données de haute résolution en multi-longueur d'onde fournies par CANDELS, j'ai réalisé une décomposition séparant le bulbe du disque à partir des courbes de brillance de surface de 17'300 galaxies (F160W<23,0<z<2) dans 4 à 7 filtres couvrant un intervalle spectral compris entre 430 et 1600 nm. Une approche novatrice, basée sur un deep-learning, nous permet de sélectionner a priori les meilleurs profils et de réduire de fait la contamination. J'ai ajusté la SED (densité spectrale d'énergie) avec des modèles de population stellaires (BC03) de disque et de bulbe de manière indépendante afin d'obtenir les paramètres des populations stellaires (masses stellaires, couleurs). Cette procédure fournit un catalogue contenant à la fois les informations structurelles/morphologiques et les propriétés des populations stellaires d'un vaste échantillon de bulbes et de disques galactiques fournit à la communauté (lerma.obspm.fr/huertas/form_CANDELS). Il s'agit du catalogue le plus grand et le plus complet décomposant le bulbe du disque galactique à des redshifts z>0. J'ai utilisé le catalogue ainsi obtenu pour comprendre comment les galaxies stoppent leur formation d'étoile et déterminer l'impact que le quenching peut avoir sur les composantes internes. Les propriétés structurelles des bulbes et des disques, bien que différentes, dépendent peu de la morphologie globale de la galaxie hôte et de son activité de formation d'étoile. Si il existe un seul mécanisme de formation pour tous les types de galaxie ou plusieurs mécanismes contribuant à l'augmentation de la densité centrale, aucune trace dans la structure de la composante interne n'est gardée. De plus, les bulbes et les disques évoluant dans des galaxies soit éteintes, soit formant des étoiles (SF), bien qu'ils présentent des propriétés structurelles similaires, possèdent des distributions de couleurs différentes. Le processus de quenching ne semble pas avoir un impact significatif sur les propriétés des composantes internes.La seconde question clé est de savoir à quel moment les bulbes se forment. La distribution en morphologie le long du graphe SFR-masse montre un manque de galaxie calme (quiescent) avec B/T<0.3 alors que les galaxies avec B/T>0.3 sont présentes tout au long de la séquence principale. Cela suggère que la formation du bulbe doit commencer au cours de la séquence principale. De plus, nous n'avons aucune preuve d'un quelconque processus quenching sans qu'il y ait grossissement du bulbe. Nous n'excluons cependant pas la possibilité que les bulbes de la séquence principale correspondent à des galaxies ayant ré-accrété un disque formant des étoiles. La connaissance des âges est à ce niveau nécessaire pour réellement contraindre ce scénario. Une analyse élargie qui inclurait de l'imagerie à bande étroite (SHARDS) permettrait d'explorer les âges typiques des bulbes et des disques afin de placer des contraintes sur leur temps de formation. / Passive galaxies have different morphologies and structural properties than star-forming galaxies of similar mass. The evidence of a bimodal distribution of galaxy properties suggests a link between the quenching process and and galaxy structure. Understanding the origin of this correlation requires establishing constraints on the mechanisms as well as on the timing of bulge formation. How are bulges formed?Do bulges grow in the main sequence? Are galaxies re-accreting a star forming disk? Do galaxies start to quench from the inside? etc.Proper answers to these questions require resolving the internal components of galaxies at different epochs.Thanks to the CANDELS high-resolution multi-wavelength data, I performed 2-D bulge-disk decompositions of the surface brightness profile of $simeq 17'300$ galaxies (F160W < 23, 0 < z < 2) in 4-7 filters, covering a spectral distribution of 430-1600 nm. A novel approach, based on deep-learning, allowed us to make an a-priori selection of the best profile. Stellar parameters are computed trough the SED fitting. The final catalog contains structural/morphological informations together with the stellar population properties for a large sample of bulges and disks within galaxies. This is the largest and more complete catalog of bulge-disc decompositions at $z>0$.The catalog is then used to investigate how galaxies quench and transform their morphologies.The size of disks and massive bulge is independent of the bulge-to-total ratio ($M_{*}>10^{10} M_{odot}$). It suggests a unique formation process for massive bulges and also that disk survival/regrowth is a common phenomenon after bulge formation. However pure bulges (B/T>0.8), are ~30% larger than bulges embedded in disks at fixed stellar mass and have larger Sersic indices. This is compatible with a later growth of these systems through minor mergers.Bulges in star-forming galaxies are found to be 30% larger than bulges in quenched systems, at fixed stellar mass. Regarding the disks the systematic difference is only a factor of $sim 0.1$. This can be interpreted as a signature that galaxies experience an additional morphological transformation during or after quenching. However, this result is not free of progenitor bias.Moreover, the vast majority (if not all) of pure disks (B/T<0.2) in our sample lie in the main-sequence. It suggests that quenching without any bulge growth is not a common channel at least in the general field environment probed by our data. Pure "blue" bulges (B/T>0.8) do exist however, suggesting that the formation of bulges happens while galaxies are still star forming.Finally, in order to put constraints on the formation times of bulges and disks I analyzed the UVJ colors rest frame. Almost all galaxies in our sample present negative color gradients. Bulges are always redder than the disks at all redshifts. This is compatible with a scenario of inside-out quenching put forward by previous works. However rejuvenation through disk accretion could lead to similar signatures.

The Apache Point Observatory Galactic Evolution Experiment (APOGEE), one of the programs in the Sloan Digital Sky Survey III (SDSS-III), has now completed its systematic, homogeneous spectroscopic survey sampling all major populations of the Milky Way. After a three-year observing campaign on the Sloan 2.5 m Telescope, APOGEE has collected a half million high-resolution (R similar to 22,500), high signal-to-noise ratio (>100), infrared (1.51-1.70 mu m) spectra for 146,000 stars, with time series information via repeat visits to most of these stars. This paper describes the motivations for the survey and its overall design-hardware, field placement, target selection, operations-and gives an overview of these aspects as well as the data reduction, analysis, and products. An index is also given to the complement of technical papers that describe various critical survey components in detail. Finally, we discuss the achieved survey performance and illustrate the variety of potential uses of the data products by way of a number of science demonstrations, which span from time series analysis of stellar spectral variations and radial velocity variations from stellar companions, to spatial maps of kinematics, metallicity, and abundance patterns across the Galaxy and as a function of age, to new views of the interstellar medium, the chemistry of star clusters, and the discovery of rare stellar species. As part of SDSS-III Data Release 12 and later releases, all of the APOGEE data products are publicly available.

Until recently, obtaining rest-frame optical spectra of galaxies at z > 1 was a time consuming and challenging observation due to the difficult nature of near-infrared (near-IR) spectroscopy. However, with the advent of second generation ground-based near-IR spectrographs (e.g. KMOS, MOSFIRE), and the new low resolution near-IR grisms on the Hubble Space Telescope (HST), we have entered a new era in the study of high redshift galaxies. This thesis explores the physical properties of star-forming galaxies in the redshift range 1 < z < 3 by utilising a custom reduction of the 3D-HST near-IR grism spectroscopic survey. One of the most important observational constraints on the evolution of galaxies is the mass-metallicity relation (MZR), which is sensitive to both the star-formation history and various inflow/outflow processes. I use the 3D-HST spectra to provide a new constraint on the MZR at 2:0 < z < 2:3, and moreover measure the O/H abundance directly from the oxygen and hydrogen emission lines ([OII], [OIII] and Hβ) as opposed to the more common method at high redshift of inferring O/H from the N/H ratio (via [NII] and Hα). I show that the traditional form of the MZR is recovered from the 3D-HST data, with metallicity increasing with the stellar mass of a galaxy. However, the absolute metallicity values I derive are inconsistent with previous N/H-based measurements of metallicity at these redshifts. Moreover, I show that the 3D-HST data is inconsistent with the `fundamental metallicity relation' (FMR), and that, contrary to previous claims, this local Universe relation may not hold out to z & 2. To investigate this metallicity discrepancy further, I measure the evolution of the [OIII]/Hβ nebular emission line ratio in the 3D-HST spectra over the redshift range 1:3 < z < 2:3. I compare this observed line ratio evolution with state-of-the- art theoretical models which take into account the independent evolution of the ionization parameter, electron density and metallicity of star-forming regions with redshift. The homogeneous 3D-HST dataset allows me to perform a consistent analysis of this evolution which takes into account line luminosity selection effects. I show that, according to models, the observed [OIII]/Hβ evolution cannot be accounted for by pure metallicity evolution. Instead I am able to infer that the line ratio evolution is more consistent with, at the very least, an evolution to stronger ionizing conditions at high redshift, and perhaps even denser star-forming regions. I explore how this result can also explain the observed discrepancy between high redshift metallicity measurements. In light of this finding, I revisit the MZR at z >~ 2 and employ a purely theoretical approach to inferring metallicities from nebular lines, which is able to account for an evolution in ionization conditions. I then use a selection of galaxies from the local Universe, which mimic the properties of high redshift galaxies, to derive a more robust ionization sensitive, conversion, between N/H and O/H. With this new conversion which I am able to bring the previous inconsistent metallicity measurements at z >~ 2 back into agreement. Finally, I am able to show that, in this new formalism, the metallicity evolution between z = 2 and z = 3 is perhaps not as large as previously reported. To conclude I discuss ongoing work as part of the KMOS Deep Survey (KDS) being undertaken with the near near-IR Multi-Object Spectrograph KMOS on the VLT. I describe the observations and data reduction that has been completed to date and describe how this instrument will allow me to extend the work presented in this thesis to z > 3. I also introduce FIGS, a new HST near-IR grism survey seeking to spectroscopically identify galaxies at 5:5 < z < 8:5 and work I have begun in exploring this dataset.

L'objectif de cette thèse est d'identifier et d'étudier la population à haut décalage spectral. J'ai utilisé des données dans le proches infrarouge venant du sondage UltraVista associé à des données multi-longueur d'onde disponible dans le champ COSMOS ainsi que le sondage ultra profond de VIMOS utilisé comme un échantillon de contrôle pour la sélection des candidats à grand décalage spectrale. Cette analyse m'a amené à sélectionner des galaxies à z>4.5 en utilisant les décalages spectraux photométriques estimés à partir de la distribution spectrale d'énergie complète ainsi que des limites en magnitudes basés sur la profondeur des données dans chaque bande. Cette sélection a amené à la production d'un catalogue unique de 2036 galaxies dans l'intervalle z~5 et de 330 galaxies dans l'intervalle z~6 faisant de ce catalogue le catalogue le plus grand et le plus complet à ce jour. J'ai trouvé que la fonction de luminosité à z~5 est bien reproduite par une fonction de Schechter. A z~6, j'ai observé que le fin lumineuse de la fonction de luminosité semble être plus peuplée qu'une fonction de Schechter le laisse présager, en accord avec les résultats d'autres études Ceci étant une indication que les processus d'assemblage de la masse ont évolué rapidement. Finalement, j'ai intégré la fonction de luminosité pour en déduire la densité de luminosité et dérivé la densité de formation stellaire entre z=4.5 et z=6.5. Mes résultats montrent une densité de formation stellaire importante, en comparaison des derniers résultats avec les données du télescope Hubble, ainsi qu'une précision plus grande liée aux meilleures contraintes sur la fin lumineuse de la fonction de luminosité. / The main purpose of this THESIS is to identify and study the population of high redshift galaxies in the redshift range (4.5 < z < 6.5). I use the near infrared data from the UltraVista survey conducted with the Vista telescope in combination with multi-wavelength data available in the COSMOS field and use The VIMOS Ultra Deep spectroscopic redshift survey (VUDS) as a control sample for the selection of high redshift candidates. I made a analysis leads me to select galaxies at z ≥ 4.5 using photometric redshifts computed from the full spectral energy distribution (SED) combined with well tuned magnitude limits based on the depth of the data in each band. At the end of this process I produce a unique catalogue of 2036 galaxies with 4.5 ≤ z ≤ 5.5 and 330 galaxies with 5.5 ≤ z ≤ 6.5, the largest and most complete catalogue of sources at these redshifts existing today. I find that the LF at z ∼ 5 is well fit by a Schechter function. At z ∼ 6 I find that the bright end might be more populated than expected from a Schechter function, in line with results from other authors, an indication that the mass assembly processes have evolved quickly in a short 0.5-1 Gyr timescale. Finally I integrate the luminosity functions to compute the luminosity density and derive the star formation rate density (SFRD) in 4.5 ≤ z ≤ 6.5. My results show a high SFRD comparable to the latest results derived from the HST data, with an improved accuracy linked to the better constraints at the bright end of the LF.

Nesta tese, investigamos a discrepância existente entre o número de galáxias satéli-tes da Via Láctea que é previsto e aquele que é observado, questão conhecida como ``problema da falta de satélites\'\' (PFS). Este problema pode ser reformulado em termos de um desacordo entre a função de luminosidades das galáxias satélites (FLS) que é estimada a partir de dados observacionais e a FLS predita por modelos numéricos de formação de galáxias. Nós revisamos tanto propriedades observacionais da população de satélites quanto a teoria associada à modelagem da formação de galáxias e estruturas. Para abordar o PFS, estudamos diferentes soluções possíveis. Nós desenvolvemos uma modificação simples ao potencial do inflaton usual e mostramos que esta leva a uma redução no número de halos de matéria escura de pequena massa. Nós usamos, então, um modelo semi-analítico de formação de galáxias para confirmar que supressões similares do espectro de potências de pequena escala produzem uma FLS com a forma correta. Em uma outra direção, nós discutimos outros mecanismos astrofísicos capazes de reduzir o número de galáxias pequenas, especificamente: os ventos gerados por explosões de supernovas e o aquecimento do meio intergalático durante a reionização do Universo. Finalmente, nós estudamos como um campo magnético primordial pode influenciar a formação de galáxias de pequena massa. Para isso, nós inicialmente mostramos que a pressão devida a um campo magnético leva a uma alteração significativa na massa de filtragem, levando a uma importante supressão na acresção de gás por galáxias de baixa massa. Introduzindo estas modifi-cações em um modelo numérico de formação de galáxias, mostramos que, para valo-res realistas de intensidade de campo, a pressão devido ao campo magnético leva a um bom acordo entre a FLS prevista e observada. / In this thesis we investigate the discrepancy between the predicted and observed number of satellite galaxies in the Milky Way, known as ``the missing satellites problem\'\' (MSP). This problem can be translated into the disagreement between the satellite luminosity function (SLF), which is estimated from the observational (particularly the SDSS) data and the SLF predicted by numerical models of galaxy formation. We review both the observational properties of the satellite population and the essentials of galaxy and structure formation modelling. To tackle the MSP, we study different possible solutions. We develop a small modification to the usual chaotic inflaton potential and show that it leads to a reduction in the number of small mass haloes. We use a semi-analytic model of galaxy formation to confirm that suppressions of the small scale power spectrum can produce a SLF with the correct shape. In a different direction, we discuss other astrophysical mechanisms that can reduce the number of small mass galaxies, namely: the outflows generated by supernovae explosions and the heating of the intergalactic medium during the reionization of the Universe. Finally, we study how a primordial magnetic field can influence the formation of small mass galaxies. We first find that small primordial magnetic field significantly change the filtering mass, leading to an important suppression in the gas accretion by small mass haloes. ( The filtering mass is the mass for which the baryon accretion is reduced to approximately 1/2 its normal value.) Introducing these modifications in the galaxy formation model, we show that for realistic field strengths, the pressure due to the magnetic field can result in a good match between the observed SLF and the model predictions.

Nós realizamos um estudo estatístico do comportamento de perfis de cor em bandas largas (UBV) para 257 galáxias espirais do tipo Sbc, ordinárias e barradas, utilizando dados obtidos através de fotometria fotoelétrica de abertura, disponíveis na literatura (Longo & de Vaucouleurs 1983,1985). Nós determinamos os gradientes de cor (B-V) e (U-B) para as galáxias da amostra total, bem como os índices de cor (B-V) e (U-B) de bojos e discos separadamente, utilizando métodos estatísticos robustos. Utilizamos uma técnica de decomposição bi-dimensional para modelar os perfis de brilho de bojos e discos em imagens dos arquivos do ``Digitised Sky Survey' (DSS), obtendo parâmetros estruturais característicos para 39 galáxias. A aquisição de imagens de 14 galáxias no Laboratório Nacional de Astrofísica permitiu-nos realizar um estudo fotométrico comparativo, e atestar a validade dos resultados obtidos neste estudo. Entre os principais resultados obtidos, destacam-se: (i) - 65% das galáxias possuem gradientes de cor negativos (mais vermelhos no centro), 25% possuem gradientes nulos, e 10% apresentam gradientes positivos; (ii) - galáxias que apresentam gradientes de cor nulos tendem a ser barradas; (iii) - os índices de cor ao longo das galáxias com gradientes nulos são similares aos índices de cor dos discos das galáxias com gradientes negativos; (iv) - confirmamos a correlação entre os índices de cor de bojos e discos, já obtida por outros autores; (v) - a ausência de correlação entre os gradientes de cor e de metalicidade sugere que o excesso de galáxias barradas com gradientes de cor nulos ou positivos reflete uma diferença no comportamento da idade média da população estelar ao longo de galáxias barradas e ordinárias; (vi) - galáxias com gradientes de cor nulos ou positivos têm uma leve tendência a apresentar bojos maiores e com maior concentração central de luz; e (vii) - confirmamos a correlação entre as escalas de comprimento de bojos e discos, já obtida por outros autores. Estes resultados são compatíveis e favoráveis ao cenário de evolução secular, no qual barras produzem fluxos radiais de massa para as regiões centrais de galáxias, não somente homogeneizando as populações estelares ao longo de galáxias, produzindo discos e bojos com índices de cor semelhantes, mas também contribuindo para a formação e/ou construção de bojos. / We have done a statistical study of the behaviour of the broadband color profiles (UBV) for 257 Sbc galaxies, barred and unbarred, collecting data obtained through photoeletric aperture photometry, available in the literature (Longo & de Vaucouleurs 1983,1985). We have determined (B-V) and (U-B) color gradients for the total sample of galaxies, as well as (B-V) and (U-B) color indices of bulges and disks separately, using robust statistical methods. Applying a bi-dimensional decomposition technique to model the brightness profiles of bulges and disks in images from the Digitised Sky Survey (DSS), we obtained characteristic structural parameters for 39 galaxies. The acquisition of images for 14 galaxies in the Laboratório Nacional de Astrofísica (Astrophysics National Laboratory) allowed us to do a comparative photometric study, and verify the validity of the results obtained in this work. Among the main results obtained, we point out: (i) - 65% of the galaxies have negative color gradients (reddish inward), 25% have zero gradients, and 10% show positive gradients; (ii) - galaxies that show zero color gradients tend to be barred; (iii) - the color indices along the galaxies with zero color gradients are similar to the color indices of the disks of the galaxies with negative color gradients; (iv) - we confirm the correlation between the color indices of bulges and disks, already found by other authors; (v) - the absence of correlation between color and metallicity gradients suggests that the excess of barred galaxies with zero or positive color gradients reflects a difference in the behaviour of the mean age of the stellar population along barred and unbarred galaxies; (vi) - galaxies with zero or positive color gradients show a slight tendency of having larger bulges, with a greater central concentration of light; and (vii) - we confirm the correlation between the scale lenghts of bulges and disks, already found by other authors. These results are compatible and favourable to the secular evolutionary scenario, in which stellar bars induce radial mass fluxes to the central regions of galaxies, not only turning homogeneous the stellar populations along the galaxies, producing disks and bulges with similar color indices, but also contributing to the formation and/or building of galactic bulges.

<p>  Understanding the formation and evolution of galaxies is one of the most fundamental questions in modern astronomy. While it is widely accepted that galaxy formation needs to be understood in the context of cosmic structure formation of dark matter, a complex interplay of different physical processes that drive galaxy formation makes it challenging to elucidate how the large-scale environment of dark matter influences galaxies, particularly in their formative epoch (z > 2). </p> <p>    As the most luminous nebular emission arising from star formation,  Lyalpha provides a promising and effective tool to study the young universe and nascent galaxies.</p> <p>  At z>2, Lyalpha emission is redshifted into the visible window that is detectable by ground-based telescopes. Existing studies also suggest that strong Lyalpha-emitting galaxies represent a young and low-mass galaxy population and therefore are the best visible tracers of the large-scale structure of the distant universe. </p> <p>    In this thesis, I present two complementary studies designed to address these questions using Lyalpha emission as a cosmological tool. In Chapter 2, I investigate the kinematics and spatial distribution of the gas-phase interstellar and circumgalactic media using compact and diffuse Lyalpha emission in and around distant galaxies. I also carry out a comprehensive characterization of how Lyalpha properties correlate with other galaxy properties and the environment that galaxies reside in. In Chapter 3, I explore how Lyalpha-emitting galaxies trace the large-scale structure characterized by other means; I also conduct a detailed investigation of the distribution of different `types' of galaxies and H i gas  in  and around the most massive cosmic structure known to date. These investigations are informative in  building clear  expectations for the ongoing and upcoming experiments -- including the Legacy Survey for Space and Time, James Webb Space Telescope, Dark Energy Spectroscopic Instruments, and Hobby-Eberly Telescope Dark Energy eXperiment -- in obtaining a detailed picture of galaxy evolution in the context of their environments. </p>

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