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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
601

“Vi håller aldrig på med realism...” : En kvalitativ undersökning om ljudets funktioner för en autentisk filmupplevelse

Larsson, Henrik January 2017 (has links)
Uppsatsen ämnar att ge en djupare förståelse för ljud i film och dess funktioner för en autentisk och realistisk filmupplevelse. Ljudet är sällan något man som åskådare lägger aktivt fokus på under en film med undantaget att man tycker att något inte stämmer. Så vad är det som krävs för att man inte ska ifrågasätta ljudet? Kvalitativa intervjuer med två personer yrkesaktiva inom ljudläggning samt en forskare inom ämnet har utförts för att kunna redovisa ingående tankar och åsikter om vad de anser vara ljudets viktigaste funktioner i modern film. Synkro nise ring och klang är centrala begrepp i undersökningen . De är exempel på faktorer som kan påverka hur man uppfattar kopplingen mellan ljud och bild. Med hjälp av uppsatsens insamlade data samt dess teoriavsnitt har dessa faktorer vidare konkretiserats genom en kort analys av tre utvalda scener från filmen Star Wars (1977). Uppsatsens mest centrala resultat baserar sig i idéen om samverkan mellan ljud och bild. Bilden klassas som det mest centrala i en film och ljud finns till för att förstärka eller berätta saker som bilden inte kan. Vad gäller realism inom filmljud så existerar det nästan inte. Det vi uppfattar som realistiskt behöver inte ha något med faktisk realism att göra. Uppsatsens diskussionsavsnitt berör studiens styrkor, svagheter samt förslag till fortsatt forskning.
602

Spatially Resolved Dust, Gas, and Star Formation in the Dwarf Magellanic Irregular NGC 4449

Calzetti, D., Wilson, G. W., Draine, B. T., Roussel, H., Johnson, K. E., Heyer, M. H., Wall, W. F., Grasha, K., Battisti, A., Andrews, J. E., Kirkpatrick, A., González, D. Rosa, Vega, O., Puschnig, J., Yun, M., Östlin, G., Evans, A. S., Tang, Y., Lowenthal, J., Sánchez-Arguelles, D. 12 January 2018 (has links)
We investigate the relation between gas and star formation in subgalactic regions, similar to 360. pc to similar to 1.5. kpc in size, within the nearby starburst dwarf NGC 4449, in order to separate the underlying relation from the effects of sampling at varying spatial scales. Dust and gas mass surface densities are derived by combining new observations at 1.1. mm, obtained with the AzTEC instrument on the Large Millimeter Telescope, with archival infrared images in the range 8-500 mu m from the Spitzer Space Telescope and the Herschel Space Observatory. We extend the dynamic range of our millimeter (and dust) maps at the faint end, using a correlation between the far-infrared/millimeter colors F(70)/F(1100) (and F(160)/F(1100)) and the mid-infrared color F(8)/F(24) that we establish for the first time for this and other galaxies. Supplementing our data with maps of the extinction-corrected star formation rate (SFR) surface density, we measure both the SFR-molecular gas and the SFR-total. gas relations in NGC 4449. We find that the SFR-molecular. gas relation is described by a power law with an exponent that decreases from similar to 1.5 to similar to 1.2 for increasing region size, while the exponent of the SFR-total. gas relation remains constant with a value of similar to 1.5 independent of region size. We attribute the molecular law behavior to the increasingly better sampling of the molecular cloud mass function at larger region sizes; conversely, the total gas law behavior likely results from the balance between the atomic and molecular gas phases achieved in regions of active star formation. Our results indicate a nonlinear relation between SFR and gas surface density in NGC 4449, similar to what is observed for galaxy samples.
603

User-centred redesign of a business systemusing the Star Life Cycle method

Ahlström, Martin January 2008 (has links)
The purpose with this thesis was to study user activities in a business system, MediusFlow. The overall objective was to identify user related problems and to analyse which of the usability data gathering methods to use in the future development process of the company Medius. The outcome of this study indicated that a cognitive related user problem was the most important problem to solve. A Star Life Cycle method was preferred. Two low-fidelity prototypes were developed to exemplify an alternative design solution to the identified cognitive user problem. Furthermore, the two best methods to use when gathering user related requirements were heuristic evaluation and expert review. In addition a company specific Style Guide was created with generic guidelines as a foundation for development of future applications within Medius.
604

Étude des processus physiques de la formation d'étoiles par effondrement gravo-turbulent / Study of the physical processes involved in star formation by turbulent gravitational collapse

Marchand, Pierre 21 September 2017 (has links)
La régulation du moment cinétique est l'une des questions les plus importantes dans la formation d'étoiles. Du nuage moléculaire à l'étoile finale, le système perd la grande majorité de son moment cinétique et plusieurs processus sont avancés pour l'expliquer. Nous nous concentrons sur la magneto-hydrodynamique (MHD) non-idéale, qui permet de décrire le couplage entre un champ magnétique et un fluide. Son efficacité pour réguler le moment cinétique dans des conditions réalistes a été montrée à plusieurs reprises. Dans un premier temps, nous développons un code qui calcule l'équilibre chimique d'éléments présents dans les premières étapes de la formation d'étoile. Ainsi, nous pouvons retrouver la valeur des coefficients définissant l'intensité de chaque processus de la MHD non-idéale. Nous nous intéressons ensuite à l'un d'entre eux, l'effet Hall, encore peu étudié dans ce contexte. Nous l'implémentons dans le code eulérien RAMSES, et l'utilisons pour quantifier son influence pendant un effondrement gravitationnel. Comme prévu par la théorie, l'effet Hall influence grandement la taille du disque protoplanétaire, dans lequel se forment les planètes, et crée des enveloppes de gas tournant en sens inverse du reste du système / The angular momentum regulation is a hot topic in star formation. From the molecular cloud to th final star, the system loses most of its angular momentum, and several processes are proposed to explain this phenomenon. We focus on non-ideal magnetohydrodynamics (MHD), which describes the coupling between a fluid and its magnetic field. Its efficiency to regulate the angular momentum in realistic conditions has been shown in several studies. First, we develop a code that computes the chemical equilibrium of elements present in the early stages of star formation. We can therefore obtain the values of coefficients defining the strength of the phyical processes associated with non-ideal MHD. We then take interest in one of them, the Hall effect, still poorly studied in this context. We implement it in the eulerian code RAMSES, and use it to quantify its influence during a gravitational collapse. As predicted by theory, the Hall effect greatly influences the size of the protoplanetary disk, in which planets form, and creates envelopes of gas rotating backward compared to the rest of the system
605

The GALEX/S4G Surface Brightness and Color Profiles Catalog. I. Surface Photometry and Color Gradients of Galaxies

Bouquin, Alexandre Y. K., Gil de Paz, Armando, Muñoz-Mateos, Juan Carlos, Boissier, Samuel, Sheth, Kartik, Zaritsky, Dennis, Peletier, Reynier F., Knapen, Johan H., Gallego, Jesús 25 January 2018 (has links)
We present new spatially resolved surface photometry in the far-ultraviolet (FUV) and near-ultraviolet (NUV) from images obtained by the Galaxy Evolution Explorer (GALEX) and IRAC1 (3.6 mu m) photometry from the Spitzer Survey of Stellar Structure in Galaxies (S(4)G). We analyze the radial surface brightness profiles mu(FUV), mu(NUV), and mu[3.6], as well as the radial profiles of (FUV - NUV), (NUV -[3.6]), and (FUV -[3.6]) colors in 1931 nearby galaxies (z < 0.01). The analysis of the 3.6 mu m surface brightness profiles also allows us to separate the bulge and disk components in a quasi-automatic way and to compare their light and color distribution with those predicted by the chemo-spectrophotometric models for the evolution of galaxy disks of Boissier & Prantzos. The exponential disk component is best isolated by setting an inner radial cutoff and an upper surface brightness limit in stellar mass surface density. The best-fitting models to the measured scale length and central surface brightness values yield distributions of spin and circular velocity within a factor of two of those obtained via direct kinematic measurements. We find that at a surface brightness fainter than mu([3.6]) = 20.89 mag arcsec(-2), or below 3 x 10(8) M-circle dot kpc(-2) in stellar mass surface density, the average specific star formation rate (sSFR) for star-forming and quiescent galaxies remains relatively flat with radius. However, a large fraction of GALEX Green Valley galaxies show a radial decrease in sSFR. This behavior suggests that an outside-in damping mechanism, possibly related to environmental effects, could be testimony of an early evolution of galaxies from the blue sequence of star-forming galaxies toward the red sequence of quiescent galaxies.
606

A Phylogenetic Revision of Superfamily Himerometroidea (Echinodermata: Crinoidea)

Taylor, Kristian 26 August 2015 (has links)
Superfamily Himerometroidea AH Clark, 1908 (Echinodermata: Crinoidea) (formerly Mariametroidea) is the second most speciose superfamily in order Comatulida. Although it includes some of the most common species on tropical western Pacific reefs, its phylogeny is poorly understood. Genus- to species-level taxa are currently distinguished by plastic morphological characters. We revised the superfamily from species- to family-levels using a combined morphological and molecular approach. A phylogeny using two nuclear and three mitochondrial markers recovered Colobometridae and Himerometridae as paraphyletic and Mariametridae and Zygometridae as polyphyletic. Within genus Himerometra (Himerometridae), sequence data and detailed morphological examinations of multiple specimens of H. magnipinna, H. martensi and H. robustipinna indicated that these three taxa are conspecific. A similar examination of specimens attributed on morphological grounds to the genera Dichrometra, Liparometra and Lamprometra (Mariametridae) revealed a lack of substantial enough sequence and morphological differences to maintain them as distinct genera. We have synonymized all three genera and redescribed four species under the senior name Dichrometra. Additional work is needed to more clearly establish characters that will diagnose clades across the superfamily. This study illustrates the importance of reevaluating classifications that incorporate ecophenotypically and ontogenetically variable characters.
607

Planck’s dusty GEMS

Cañameras, R., Nesvadba, N., Kneissl, R., Frye, B., Gavazzi, R., Koenig, S., Le Floc’h, E., Limousin, M., Oteo, I., Scott, D. 23 August 2017 (has links)
We present an analysis of high-resolution ALMA interferometry of CO(4-3) line emission and dust continuum in the "Ruby" (PLCK_G244.8+54.9), a bright, gravitationally lensed galaxy at z = 3.0 discovered with the Planck all-sky survey. The Ruby is the brightest of Planck's dusty GEMS, a sample of 11 of the brightest gravitationally lensed high-redshift galaxies on the extragalactic sub-mm sky. We resolve the high-surface-brightness continuum and CO line emission of the Ruby in several extended clumps along a partial, nearly circular Einstein ring with 1.4 '' diameter around a massive galaxy at z = 1.5. Local star-formation intensities are up to 2000 M-circle dot yr(-1) kpc(-2), amongst the highest observed at high redshift, and clearly in the range of maximal starbursts. Gas-mass surface densities are a few x10(4) M-circle dot pc(-2). The Ruby lies at, and in part even above, the starburst sequence in the Schmidt-Kennicutt diagram, and at the limit expected for star formation that is self-regulated through the kinetic energy injection from radiation pressure, stellar winds, and supernovae. We show that these processes can also inject sufficient kinetic energy and momentum into the gas to explain the turbulent line widths, which are consistent with marginally gravitationally bound molecular clouds embedded in a critically Toomre-stable disk. The star-formation efficiency is in the range 1-10% per free-fall time, consistent with the notion that the pressure balance that sets the local star-formation law in the Milky Way may well be universal out to the highest star-formation intensities. AGN feedback is not necessary to regulate the star formation in the Ruby, in agreement with the absence of a bright AGN component in the infrared and radio regimes.
608

Boötes-HiZELS: an optical to near-infrared survey of emission-line galaxies at z = 0.4–4.7

Matthee, Jorryt, Sobral, David, Best, Philip, Smail, Ian, Bian, Fuyan, Darvish, Behnam, Röttgering, Huub, Fan, Xiaohui 10 1900 (has links)
We present a sample of similar to 1000 emission-line galaxies at z = 0.4-4.7 from the similar to 0.7deg(2) High-z Emission-Line Survey in the Bootes field identified with a suite of six narrow-band filters at approximate to 0.4-2.1 mu m. These galaxies have been selected on their Ly alpha (73), [O (II)] (285), H beta/[O (III)] (387) or H alpha (362) emission line, and have been classified with optical to near-infrared colours. A subsample of 98 sources have reliable redshifts from multiple narrow-band (e.g. [O (II)]-H alpha) detections and/or spectroscopy. In this survey paper, we present the observations, selection and catalogues of emitters. We measure number densities of Ly alpha, [O (II)], H beta/[O (III)] and H alpha and confirm strong luminosity evolution in star-forming galaxies from z similar to 0.4 to similar to 5, in agreement with previous results. To demonstrate the usefulness of dual-line emitters, we use the sample of dual [O (II)]-H alpha emitters to measure the observed [O (II)]/H alpha ratio at z = 1.47. The observed [O (II)]/H alpha ratio increases significantly from 0.40 +/- 0.01 at z = 0.1 to 0.52 +/- 0.05 at z = 1.47, which we attribute to either decreasing dust attenuation with redshift, or due to a bias in the (typically) fibre measurements in the local Universe that only measure the central kpc regions. At the bright end, we find that both the H alpha and Ly alpha number densities at z approximate to 2.2 deviate significantly from a Schechter form, following a power law. We show that this is driven entirely by an increasing X-ray/active galactic nucleus fraction with line luminosity, which reaches approximate to 100 per cent at line luminosities L greater than or similar to 3 x 10(44) erg s(-1).
609

Molécules conjugées en étoile à base d'azophénine : synthèse et caractérisation photophysique / Azophenine-based star-shaped conjugated molecules: synthesis and photophysical investigation

Hu, Lei January 2017 (has links)
Cette thèse présente la conception, la synthèse et l'étude photophysique de divers dérivés d'azophénine comme modèles structurels mono-bloc pour l'éméraledine qui est une forme de polyaniline à valence mixte. L'azophénine est une molécule conjuguée en forme d'étoile contenant à la fois des résidus de quinone diimine et de phénylamine tous deux contenus dans l'émeraldine. Cependant l'azophénine et l'émeraldine sont tout deux reconnus pour ne pas être émissifs. Le défi était alors de donner des propriétés d’émissions à l'azophénine à température ambiante avant toute investigation photophysique. L'objectif à long terme étant de rendre la polyaniline, connu pour être peu dispendieuse, attractive en tant que matériau donneur efficace dans une cellule solaire de type « bulk-heterojunction ». En raison des problèmes de faible solubilité des polymères, l'utilisation de modèles beaucoup plus soluble est une nécessité. Les modifications structurelles considérées comprennent l'ancrage des fonctions pontées d'éthynyle en position para- des quatre groupes phényls d'azophénine. Ces fonctions sont des groupes aromatiques encombrés de type truxène, des composés organométalliques trans-bis(trialkylphosphine) platine(II), des colorants de porphyrines de zinc(II) et de Bodipy. Elles présentent toutes une fluorescence ou une phosphorescence, signal pouvant être utilisé pour mesurer les interactions électroniques entre ces groupements et le noyau central. Leurs propriétés photophysiques sont étudiées en détail en utilisant la spectroscopie d'absorption et d'émission UV-Visible stationnaire et ultra-rapide résolue dans le temps. La DFT et la TDDFT sont également utilisés pour les optimisations des géométries (DFT) et pour déterminer la nature et les positions de l'absorption de la bande de transfert de charge (TDDFT). Le chapitre 2 présente la synthèse et la caractérisation d'un dérivé en étoile d'azophénine autour d’un noyeau truxène appelé TertTruQ. Le couplage de résidus encombrés de truxène avec de l'azophénine a amélioré l'activité photophysique du premier niveau singulet de ce dérivé à 77 K. Les hypothèses étant que le taux de désactivation non radiatif a diminué les rotations autour des axes des liaisons C-N en raison de la taille du truxène. De plus, cette nouvelle azophénine substituée s'est révélée être fluorescente à l'état solide à température ambiante. En raison de ces nouvelles observations, les propriétés d'émission des dérivés de l’éméraldine sont réexaminées. Une fluorescence faible à ~ 780 nm à 77 K, confirmée par le spectre d'excitation, a démontré la présence d'une faible émission de type fluorescence CT dans le proche-IR pour TertTruQ. Nous pouvons en conclure que l'azophénine fournit un modèle utile pour identifier quelle modification structurelle simple peut être effectuée pour rendre l’éméraldine émissive, si possible à température ambiante. De plus, lorsqu'une espèce non luminescente devient émissive, ce changement s'accompagne d'une augmentation de sa durée de vie à l’état excitée, propriétés recherchées pour des applications dans le domaine des cellules solaires. Ce travail a été publié dans Physical Chemistry Chemical Physics, 2017, 19, 21532-21539. Le chapitre 3 décrit la synthèse et la caractérisation des azophénines contenant du trans-bis(trialkylphosphine)diéthynyl-platine(II) formant les dérivés di- et tétra-substitués DiTruPtQ et TertTruPtQ. Les deux complexes présentent une fluorescence et une phosphorescence des "bras" organométalliques à 298 K en solution. En outre, l'effet d'atome lourd du platine permet d'explorer les propriétés de l’état triplet de l'azophénine. Cependant, la phosphorescence recherchée de l'état triplet CT n'a pas été considérée probablement en raison des processus rapides non radiatifs. Ce travail a été publié dans Organometallics, 2017, 36(3), 572-581. Le chapitre 4 présente l'effet du remplacement des ions H+ labiles sur le fragment HN^N par des fragments BF2+ pour former des cycles, fournissant ainsi un cadre plus rigide pour l'azophénine. En effet, la fluorescence CT proche-IR a été observée à 298 et 77 K. Cependant, malgré la présence de Pt dans les groupes pendants, aucune phosphorescence n'a été détectée. Les calculs de DFT ont suggéré que l'état triplet de plus faible énergie était très faible (0,975 eV (BQ) et 0,84 eV (TertPtBQ)) induisant une plus grande probabilité de processus non radiatifs, depeuplant ainsi efficacement l'état triplet. Ce travail a été accepté à Inorganic Chemistry, 2017. Le chapitre 5 présente les colorants fluorescents de porphyrine de zinc(II) et BODIPY bien connus, qui ont été liés à l'azophénine pour former DiBodipyQ, TertBodipyQ et PorBodipyQ. Le spectre d'absorption des BODIPY se situe dans une gamme où la porphyrine n'absorbe pas beaucoup. Ainsi, la combinaison de ces deux chromophores avec la formation d'une bande de CT faible permet d'améliorer la collecte du rayonnement solaire. Par conséquent, il était important de vérifier que l'énergie collectée pourrait facilement être transférée d'un chromophore à l'autre. En effet, on a observé 1BODIPY * → 1porphyrine zinc(II) et 1BODIPY * → 1CT (azophénine) avec une désactivation efficace de 1porphyrine zinc(II) ~~> 1CT (azophénine). Ce travail a été soumis à Chemistry: A European Journal. / Abstract: This thesis presents the design, synthesis and photophysical investigation of various azophenine derivatives as “one unit” structural models for emeraldine, a mixed-valence form of polyaniline. Azophenine is a star-shaped cross-conjugated molecule containing both quinone diimine and phenyl amine residues included in emeraldine but both, azophenine and emeraldine, are reported notoriously non-emissive. The challenge was to render azophenine emissive at room temperature prior any photophysical investigation. The long-term objective is to render polyaniline, in one form or the other, useful in bulk heterojunction solar cell in the active layer as it is not expensive. Because of solubility issues, the use of models becomes very appealing. The considered structural modifications include the anchoring of ethynyl-bridged functions at the para-position of the four phenyl groups of azophenine. These functions are the bulky truxene aromatic, the organometallic trans-bis(trialkylphosphine)platinum(II) pendent groups, and zinc(II)porphyrin and BODIPY dyes. All these functions exhibit fluorescence or phosphorescence, signal that can be used to monitor any electronic interaction between these pendent groups and the central core. Their photophysical properties were investigated in detail using steady-state and ultrafast time-resolved UV-vis absorption and emission spectroscopy. DFT and TDDFT were also employed for geometry optimizations (DFT) and nature and positions of the CT absorption (TDDFT). Chapter 2 introduces the synthesis and characterization of a truxene-based star-shaped azophenine derivative called TertTruQ. The coupling of bulky truxene residues with azophenine improved the photophysical activity of the lowest energy singlet excited state (i.e. CT state) of this derivative at 77 K. Speculations are that the rate for non-radiative deactivation, namely internal conversion, decreased upon slowing down the rotations around the N-C bonds due to the size of truxene. Moreover, this new substituted azophenine turned out to be fluorescent in the solid state at room temperature. Because of these interesting new observations, the emission properties of emeraldine base form were re-examined. A weak fluorescence at ~780 nm at 77 K, confirmed by the excitation spectrum, demonstrated the presence a CT near-IR fluorescence for TertTruQ. Thus, azophenine provides a useful model to identify what simple structural modification that can be performed to render emeraline emissive, if possible at room temperature. Again, when a non-luminescent species becomes emissive, this change is accompanied by an increase of its excited state lifetime. Longer excited state lifetimes are more prone to solar cell applications. This work has been published in Physical Chemistry Chemical Physics, 2017. Chapter 3 describes the synthesis and characterization of trans-bis(trialkylphosphine)diethynyl-platinum(II)-containing azophenines forming the di- and tetra-substituted derivatives DiTruPtQ and TertTruPtQ. Both complexes exhibit fluorescence and phosphorescence of the organometallic “arms” at 298 K in fluid solution. Moreover, the heavy atom effect of platinum gave the possibility of exploring the triplet state properties of azophenine. However, the sought phosphorescence from the triplet CT state was not seen most presumably due to the fast non-radiative processes. This work has been published in Organometallics, 2017, 36(3), 572-581. Chapter 4 presents the effect of the replacement of the labile H+ ions on the HN^N moiety by BF2+ fragments to form cycles thus providing a more rigid framework for azophenine. Indeed, the CT near-IR fluorescence was observed both at 298 and 77 K. However, despite the presence of Pt in the pendent groups, no phosphorescence was detected. DFT computations suggested that the low-lying triplet state was very low (0.975 (BQ) and 0.84 eV) inducing a higher probability of non-radiative processes thus efficiently depleting the triplet state. This work has been submitted to Inorganice Chemistry. Chapter 5 introduces the well-known BODIPY and zinc(II)porphyrin fluorescent dyes, which were linked to azophenine to form DiBodipyQ, TertBodipyQ and PorBodipyQ. The absorption spectrum of Bodipy lies in a range where porphyrin does not absorb very much. So, the combination of these two chromophores along with the formation of a low-lying CT band improves the light collection of the solar radiation. Consequently, it was important to verify that the collected energy could easily transferred from one chromophore to another. Indeed, the 1Bodipy* → 1zinc(II)porphyrin and 1Bodipy* → 1CT(azophenine) were observed along with an efficient deactivation from 1zinc(II)porphyrin ~~> 1CT(azophenine).
610

The evolution of AGN and their host galaxies

Kalfountzou, Eleni January 2015 (has links)
Active galaxies have been in the forefront of astronomic research since their first discovery, at least 50 years ago (e.g. Schmidt, 1963; Matthews & Sandage, 1963). The putative supermassive black hole (SMBH) at their center characterizes their properties and regulates the evolution of these objects. In this thesis, I study the 'demographics' and 'ecology' of active galactic nuclei (AGN) in the context of their evolution and the interaction with their environments (mainly their host galaxy). The number density of AGN has been found to peak at 1 < z < 3 (e.g. Ueda et al., 2003; Hasinger et al., 2005; Richards et al., 2005; Aird et al., 2010), similar to the star formation history (e.g. Silverman et al., 2008a; Aird et al., 2010). However, when taking into account obscuration, faint AGN are found to peak at lower redshift (z ≤ 2) than that of bright AGN (z ≈ 2 - 3; e.g. Hasinger et al., 2005; Hopkins et al., 2007; Xue et al., 2011). This qualitative behaviour is also broadly seen in star-forming galaxies (e.g. Cowie et al., 1996) and is often referred to as 'cosmic downsizing', although this term has developed a number of usages with respect to galaxies (e.g. Bundy et al., 2006; Cimatti et al., 2006; Faber et al., 2007; Fontanot et al., 2009). Though this behaviour is well established up to z ≈ 3, the nature of how and when the initial seed of these AGNs were formed remains an open question. For this study, I use Chandra surveys to study some of the most distant AGN in the Universe (z > 3). The combination of two different size and depth Chandra surveys (Chandra-COSMOS and ChaMP) provides me with the largest to-date z > 3 AGN sample, over a wide range of rest-frame 2-10 keV luminosities [log (Lₓ/erg s⁻¹) = 43.3-46.0] and obscuration (NH = 10²⁰ - 10²³ cm⁻²). I find strong evidence about a strong decline in number density of X-ray AGN above z ≈ 3, and also the association of this decline with a luminosity-dependent density evolution (LDDE; e.g. Gilli et al., 2007). Especially at high redshifts, the different evolution models predict quite different numbers of AGNs. The large size and the wide X-ray luminosity range of this sample reduces the uncertainties of previous studies at similar redshifts making it possible to distinguish between the different models and suggest that observations appear to favour the LDDE model. The observed AGN downsizing behaviour seen via the measured X-ray luminosity function (XLF) could arise due to changes in the mass of the typical active SMBH and/or changes in the typical accretion rate. But how does the growth of SMBHs over cosmic time influence its environment? A powerful way to address this question is to compare the host galaxy properties over a wide range of AGN and accretion rate types. Radio-jets are one of the most prominent constituents of AGN as they can interact directly with the host galaxy. Although AGN with radio jets are rare (they make up to 10 per cent of the total AGN population) radio galaxies make up over 30 per cent of the massive galaxy population and it is likely that all massive galaxies go through a radio-loud phase, as the activity is expected to be cyclical (e.g Best et al., 2005). It is therefore, important to investigate the impact of radio jets on the host galaxy and particularly the star formation. The method I follow focuses on the comparison of the host galaxy properties between optically selected quasar samples, with and without strong radio emission associated with powerful radio-jets, matched in AGN luminosity. Herschel far-infrared observations are used to trace the star formation in the host galaxy, providing minimal AGN contamination. In my first approach, I have constructed a sample of radio-loud and radio-quiet quasars from the Faint Images Radio Sky at Twenty-one centimetres (FIRST) and the Sloan Digital Sky Survey Data Release 7 (SDSS DR7), over the H-ATLAS Phase 1 Area (9h, 12h and 14.5h). The main result of this work is that RLQs at lower AGN luminosities tend to have on average higher FIR and 250-μm luminosity with respect to RQQs matched in AGN luminosity and redshift. However, evolution effects could be strong as the quasars in this sample cover a wide range of redshifts (0.4 < z < 5). Therefore, I follow a second approach with the advantage of a QSO sample selection at a single redshift epoch, decomposing the evolution effects from the AGN/star-formation study. The results indicate that radio-jets in powerful QSOs can both suppress and enhance the star formation in their host galaxies. These fundings are consistent with a galaxy mass and jet-power dependence model. Then we expect more massive galaxies to have more star-formation for a given jet-power because their star-formation is more enhanced by the jet. Although radio-jets are the best candidates for a direct AGN impact to the host galaxy, many models refer to an AGN feedback associated with energetic AGN winds and outflows which are expected to suppress the star formation in powerful AGN when compared to the overall galaxy population. My results do not suggest star formation is suppressed in the hosts of optically selected QSOs at z ≈ 1, with more than 30 per cent of them being associated with strong star formation rates (SFR ≈ 350 M⊙ yr⁻¹). Although different interpretations are possible, this result can be explained through periods of enhanced AGN activity and star-forming bursts, possibly through major mergers. However, optical QSOs comprise only a small fraction of the total AGN population. Even if the 'unified model' predicts that the host galaxy properties should not be affected by the viewing angle (type-1 vs. type-2 AGN), several studies have shown results supporting a scenario departing from the basic model. Investigating star formation in the hosts of 24 μm selected type-1&2 AGN, I found that the type-2 AGNs display on average higher star-formation rate than type-1 AGNs. This result is in agreement with previous studies suggesting an undergoing transition between a hidden growth phase and an unobscured AGN phase.

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