The RHEA Spectrograph is a single-mode echelle spectrograph designed to be a replicable and cost effective method of undertaking precision radial velocity measurements. Two versions of RHEA currently exist, one located at the Australian National University in Canberra, Australia (450 - 600nm wavelength range), and another located at the Subaru Telescope in Hawaii, USA (600 - 800 nm wavelength range). Both instruments have a novel fibre feed consisting of an integral field unit injecting light into a 2D grid of single mode fibres. This grid of fibres is then reformatted into a 1D array at the input of the spectrograph (consisting of the science fibres and a reference fibre capable of receiving a white-light or xenon reference source for simultaneous calibration). The use of single mode fibres frees RHEA from the issue of modal noise and significantly reduces the size of the optics used. In addition to increasing the overall light throughput of the system, the integral field unit allows for cutting edge science goals to be achieved when operating behind the 8.2 m Subaru Telescope and the SCExAO adaptive optics system. These include, but are not limited to: resolved stellar photospheres; resolved protoplanetary disk structures; resolved Mira shocks, dust and winds; and sub-arcsecond companions. We present details and results of early tests of RHEA Subaru and progress towards the stated science goals.

The complex and diverse populations of galaxies observed today form hierarchically through past galactic mergers. Interactions between galaxies of similar masses will drastically alter the morphology, chemical composition, star-formation activity, and central black-hole accretion of their constituents. Though we can see the components and byproducts of galaxy mergers, these events endure over a timescale of hundreds of millions of years. Thus to understand the merging process from observations, astronomers are reliant on large spectroscopic surveys which will contain galaxy mergers at various stages of interaction, and those which have just experienced coalescence. Until recently, such surveys were limited to the global properties of each galaxy, constraining the global changes in chemical composition and star-formation activity, but overlooking how such changes vary across a galaxy. The advent of Integral Field Unit (IFU) spectroscopy surveys provides spatially resolved spectroscopic properties for thousands of galaxies for the first time. This thesis presents analysis of galaxy mergers from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) IFU spectroscopy survey. Enhancements and deficits in star-formation rate and metallicity, as a result of the interaction, are determined for each spatial pixel containing a spectrum (spaxel) based on well established relationships with stellar mass density. These offsets are then compressed into radial profiles to quantify how the effects of an interaction vary as a function of radius. A sample of 36 post-mergers are, on average, enhanced out to ~2 effective radii, though individual galaxies can be enhanced or suppressed in the outskirts depending on the global star-formation rate of the galaxy. The metallicity is uniformly suppressed in post-merger galaxies, in concordance with the global SFR enhancement. A sample of galaxy pairs is identified with cuts in the projected separation, the line of sight velocity difference, and the mass ratio of the interaction. I develop a method to deblend close galaxy pairs that are on the same IFU observation, and remove contribution from the companion galaxy in the radial profile. Radial profiles of SFR and metallicity offsets for the pairs sample, binned by projected separation, confirm that central enhancements in SFR increase as separation decreases. Behaviour in the outskirts is more varied, and does not appear to correlate with the projected separation or the mass ratio of the interaction. Metallicity offsets display a similar issue, showing no clear correlation with separation or mass ratio. Such ambiguity implies that multiple characteristics of the interaction and its components are required to predict the spatial changes in a galaxy merger. I propose projects that could shed light on these ambiguities. The most recent release of MaNGA will double the sample size of mergers, possibly homogenizing projected separation and mass ratio bins that may be dominated by a particular population. An analysis of interacting galaxies that do not have mass ratio measurements, but very small projected separations and highly disturbed morphologies, could provide understanding of the transition between the very end of an interaction and the state of the galaxy post-coalescence. I also propose a more complex analysis of the asymmetry of IFU spectroscopy data products, which until now have been simplified with radial profiles. Lastly, I emphasize the importance of follow up studies of the resolved molecular gas properties of merging galaxies to discern whether gas reservoir, depletion time, or both are driving the change in star-formation rate. / Graduate

Active Galactic Nuclei (AGN) are powered by gas accretion onto supermassive Black Holes (BH). The luminosity of AGN can exceed the integrated luminosity of their host galaxies by orders of magnitude, which are then classified as Quasi-Stellar Objects (QSOs). Some mechanisms are needed to trigger the nuclear activity in galaxies and to feed the nuclei with gas. Among several possibilities, such as gravitational interactions, bar instabilities, and smooth gas accretion from the environment, the dominant process has yet to be identified. Feedback from AGN may be important an important ingredient of the evolution of galaxies. However, the details of this coupling between AGN and their host galaxies remain unclear. In this work we aim to investigate the connection between the AGN and their host galaxies by studying the properties of the extendend ionised gas around AGN. Our study is based on observations of ~50 luminous, low-redshift (z<0.3) QSOs using the novel technique of integral field spectroscopy that combines imaging and spectroscopy. After spatially separating the emission of AGN-ionised gas from HII regions, ionised solely by recently formed massive stars, we demonstrate that the specific star formation rates in several disc-dominated AGN hosts are consistent with those of normal star forming galaxies, while others display no detectable star formation activity. Whether the star formation has been actively suppressed in those particular host galaxies by the AGN, or their gas content is intrinsically low, remains an open question. By studying the kinematics of the ionised gas, we find evidence for non-gravitational motions and outflows on kpc scales only in a few objects. The gas kinematics in the majority of objects however indicate a gravitational origin. It suggests that the importance of AGN feedback may have been overrated in theoretical works, at least at low redshifts. The [OIII] line is the strongest optical emission line for AGN-ionised gas, which can be extended over several kpc scales, usually called the Narrow-Line Region (NLR). We perform a systematic investigation of the NLR size and determine a NLR size-luminosity relation that is consistent with the scenario of a constant ionisation parameter throughout the NLR. We show that previous narrow-band imaging with the Hubble Space Telescope underestimated the NLR size by a factor of >2 and that the continuum AGN luminosity is better correlated with the NLR size than the [OIII] luminosity. These affects may account for the different NLR size-luminosity relations reported in previous studies. On the other hand, we do not detect extended NLRs around all QSOs, and demonstrate that the detection of extended NLRs goes along with radio emission. We employ emission line ratios as a diagnostic for the abundance of heavy elements in the gas, i.e. its metallicity, and find that the radial metallicity gradients are always flatter than in inactive disc-dominated galaxies. This can be interpreted as evidence for radial gas flows from the outskirts of these galaxies to the nucleus. Recent or ongoing galaxy interactions are likely responsible for this effect and may turn out to be a common prerequisite for QSO activity. The metallicity of bulge-dominated hosts are systematically lower than their disc-dominated counterparts, which we interpret as evidence for minor mergers, supported by our detailed study of the bulge-dominated host of the luminous QSO HE 1029-1401, or smooth gas accretion from the environment. In this line another new discovery is that HE 2158-0107 at z=0.218 is the most metal poor luminous QSO ever observed. Together with a large (30kpc) extended structure of low metallicity ionised gas, we propose smooth cold gas accretion as the most likely scenario. Theoretical studies suggested that this process is much more important at earlier epochs of the universe, so that HE 2158-0107 might be an ideal laboratory to study this mechanism of galaxy and BH growth at low redshift more detailed in the furture. / Aktive Galaxienkerne (AGN) entstehen durch die Akkretion von Gas auf massive Schwarze Löcher, welche im Zentrum jeder Galaxie mit einer spherodialen Komponente vermutet werden. Die Leuchtkraft eines AGN kann die seiner gesamten Muttergalaxie um Größenordnungen übersteigen. In diesem Fall werden AGN oft als Quasi-Stellare Objekte (Quasare) bezeichnet. Spezielle Mechanismen müssen für das Auslösen dieser Kernaktivität in Galaxien verantwortlich sein. Verschiedene Prozesse wurden bereits identifiziert, aber der entscheidende Mechanismus wurde bisher noch nicht entdeckt. Die Wechselwirkung mit einem AGN könnte außerdem einen entscheidenden Einfluss auf die Entwicklung von Galaxien haben. Es ist noch unklar wie diese Wechselwirkung genau abläuft und ob es die Sternentstehung in Galaxien beeinflusst. In dieser Arbeit studieren wir die Eigenschaften des ausgedehnten ionisierten Gases in AGN-Muttergalaxien, um mögliche Wechselwirkungen zu untersuchen. Wir benutzen dazu eine Stichprobe von ~50 Quasaren bei geringer Rotverschiebung (z<0.3), die mit der neuartigen Technik der Integralfeld-Spektroskopie beobachtet wurden. Diese Technik kombiniert bildgebende und spektroskopische Verfahren. Wir können mit unserer Analyse zeigen, dass die spezifische Sternentstehungsrate in einigen Scheiben-dominierten AGN-Muttergalaxien vergleichbar mit denen von normalen Galaxien ohne Kernaktivität ist. Allerdings können wir in einigen AGN-Muttergalaxien keine Anzeichen von Sternentstehung feststellen. Ob Sternentstehung in diesen Galaxien momentan durch die Wechselwirkung mit dem AGN unterdrückt wird, ist daher nicht eindeutig. Hinweise auf Gasausflüsse liefert die Kinematik des ionisierten Gases für einige wenige Objekte, doch die Kinematik für die meisten AGN-Muttergalaxien kann allein durch das Wirken der Gravitation erklärt werden. Daraus schließen wir, dass der Einfluss von AGN auf ihre Muttergalaxien geringer sein könnte als theoretisch angenommen wird. Die [OIII] Emissionslinie ist die stärkste optische Linie für AGN-ionisiertes Gas und kann sich über eine Region von mehreren kpc vom Kern erstrecken, die als "Narrow-Line Region" (NLR) bezeichnet wird. Durch eine systematische Untersuchung der NLR-Ausdehnung können wir eine Beziehung zwischen NLR-Radius und AGN-Leuchtkraft bestimmen. Diese Relation ist konsistent mit einem konstanten Ionisationsparameter über die gesamte Ausdehnung der NLR. Frühere Studien mit dem Hubble Weltraumteleskop unterschätzten die Größe der NLR um mehr als einen Faktor 2. Andererseits können wir nicht für alle Quasare eine ausgedehnte NLR nachweisen, wobei eine NLR-Detektion bei einer höheren Radioleuchtkraft des Quasars wahrscheinlicher ist. Dies deutet auf eine Wechselwirkung eines Radio-Jets mit dem kernumgebenden Gas hin. Wir benutzen Emissionslinien des ionisierten Gases, um den Anteil von schweren Elementen im Gas, die so genannte Metallizität, zu bestimmen. Dabei finden wir, dass die radialen Metallizitätsgradienten in Scheiben-dominierten AGN-Muttergalaxien deutlich flacher sind als in vergleichbaren Galaxien ohne Kernaktivität, was wir als Anzeichen für radialen Gastransport vom Rand der Galaxien zum Kern interpretieren. Dies könnte durch kürzliche oder immer noch andauernde gravitative Wechselwirkungen zwischen Nachbargalaxien entstanden sein und stellt eventuell eine Voraussetzung für Kernaktivität dar. Sehr interessant ist unser Ergebnis, dass die ellptischen AGN-Muttergalaxien eine geringere Metallizität aufweisen als die Spiralgalaxien. Dies könnte z.B. durch das Verschmelzen mit kleinen Nachbargalaxien induziert werden, welche eine intrinsisch geringe Metallizität aufweisen. Am Beispiel der elliptischen Muttergalaxie des Quasars HE 1029-1401 können wir durch eine detaillierte Analyse des ionisierten Gases verschiedene Indizien für einen solchen Prozess nachweisen. Eine weiteres Resultat dieser Arbeit ist die Entdeckung eines leuchtkräftigen Quasars mit der geringsten Metallizität, die bisher für solche Objekte nachgewiesen werden konnte. Wir interpretieren die geringe Metallizität und die Ausdehnung des ionisierten Gases über 30kpc als deutliche Indizien für die Akkretion von intergalaktischem Gas. Dieser Prozess findet viel häufiger im frühen Universum statt. HE 2158-0107 könnte daher ein ideales Objekt sein, um diesen Prozess im nahen Universum detaillierter studieren zu können.

Populärwissenschaftlicher Abstract: <br /> <br /> Bislang gibt es in der beobachtenden optischen Astronomie zwei verschiedene Herangehensweisen: Einerseits werden Objekte durch Kameras abbildend erfaßt, andererseits werden durch die wellenlängenabhängige Zerlegung ihres Lichtes Spektren gewonnen. Das Integral - Field - Verfahren ist eine relativ neue Technik, welche die genannten Beobachtungsmethoden vereint. Das Objektbild im Teleskopfokus wird in räumlich zerlegt und jedes Ortselement einem gemeinsamen Spektrografen zugeführt. Hierdurch wird das Objekt nicht nur zweidimensional räumlich erfaßt, sondern zusätzlich die spektrale Kompenente als dritte Dimension erhalten, weswegen das Verfahren auch als 3D-Methode bezeichnet wird. Anschaulich kann man sich das Datenresultat als eine Abbildung vorstellen, in der jeder einzelne Bildpunkt nicht mehr nur einen Intensitätswert enthält, sondern gleich ein ganzes Spektrum. Diese Technik ermöglicht es, ausgedehnte Objekte im Unterschied zu gängigen Spaltspektrografen komplett zu erfassen. Die besondere Stärke der Methode ist die Möglichkeit, die Hintergrundkontamination der unmittelbaren Umgebung des Objektes zu erfassen und in der Auswertung zu berücksichtigen. Durch diese Fähigkeit erscheint die 3D-Methode prädestiniert für den durch moderne Großteleskope erschlossenen Bereich der extragalaktischen Stellarastronomie. Die detaillierte Untersuchung aufgelöster stellare Populationen in nahegelegenen Galaxien ist erst seit kurzer Zeit dank der Fortschritte mit modernen Grossteleskopen und fortschrittlicher Instrumentierung möglich geworden. Wegen der Bedeutung für die Entstehung und Evolution von Galaxien werden diese Arbeiten zukünftig weiter an Bedeutung gewinnen.<br /> <br /> In der vorliegenden Arbeit wurde die Integral-Field-Spektroskopie an zwei planetarischen Nebeln in der nächstgelegenen großen Spiralgalaxie M31 (NGC 224) getestet, deren Helligkeiten und Koordinaten aus einer Durchmusterung vorlagen. Hierzu wurden Beobachtungen mit dem MPFS-Instrument am russischen 6m - Teleskop in Selentschuk/Kaukasus sowie mit INTEGRAL/WYFFOS am englischen William-Herschel-Teleskop auf La Palma gewonnen. Ein überraschendes Ergebnis war, daß eins der beiden Objekte falsch klassifiziert wurde. Sowohl die meßbare räumliche Ausdehnung des Objektes als auch das spektrale Erscheinungsbild schlossen die Identität mit einem planetarischen Nebel aus. Mit hoher Wahrscheinlichkeit handelt es sich um einen Supernovaüberrest, zumal im Rahmen der Fehler an gleicher Stelle eine vom Röntgensatelliten ROSAT detektierte Röntgenquelle liegt.<br /> <br /> Die in diesem Projekt verwendeten Integral-Field-Instrumente wiesen zwei verschiedene Bauweisen auf, die sich miteinander vergleichen ließen. Ein Hauptkritikpunkt der verwendeten Instrumente war ihre geringe Lichtausbeute. Die gesammelten Erfahrung fanden Eingang in das Konzept des derzeit in Potsdam in der Fertigung befindlichen 3D-Instruments PMAS (Potsdamer Multi - Apertur - Spektrophotometer), welcher zunächst für das 3.5m-Teleskop des Calar - Alto - Observatoriums in Südspanien vorgesehen ist. Um die Effizienz dieses Instrumentes zu verbessern, wurde in dieser Arbeit die Kopplung der zum Bildrasterung verwendeten Optik zu den Lichtleitfasern im Labor untersucht. Die Untersuchungen zur Maximierung von Lichtausbeute und Stabilität zeigen, daß sich die Effizienz durch Auswahl einer geeigneten Koppelmethode um etwa 20 Prozent steigern lässt. / Popular scientific abstract: <br /> <br /> Currently there are two different approaches in the observational optical astronomy: On the first hand objects are imaged with cameras, on the other hand spectra are produced. The integral-field-technique is a relatively new way to combine both branches. The object image in the telecopes focus is sampled spatially and each spatial bin assigned to a spectrograph. Hence the object is not only sampled spatially but the spectral component is achieved as a third dimension, so the name 3D-Method. The result is like an image but each point consists of a whole spectrum. The use of this technique is to sample objects completely in contrast to standard slit spectroscopy. The strength of this method is to deal with high background light contamination. So the 3D method looks convincing for the new branch of extragalactic stellar astronomy with modern large telescopes. The detailled investigation of spatially resolved extragalactic populations in nearby galaxies is a rather new topic demanding newest telescopes and instrumentation. These investigations are very important in future to understand the origin and evolution of galaxies.<br /> <br /> In this thesis the Integral-Field-Spectroscopy was tested for two planetary nebulae in the Andromeda galaxy M31. Observations have been made using the MPFS on the Russian 6m telescope and the INTEGRAL/WYFFOS setup on the 4.2m WHT on La Palma. A surprising result was that one of the two objects was wrongly identified as a planetary nebula. The spatial extension and spectral details excluded this object class. With high probability this object is a supernova remnant.<br /> <br /> The integral-field-instruments used in this thesis had different technical layouts, which were to compare to each other. The main critics is the poor efficiency of both devices. The experience made was utilized to optimize the concept of the recently developed 3D-instrument PMAS (Potsdam Multi- Aperture Spectrophotometer). PMAS will be used for the 3.5 m telescope at the Calar Alto observatory. To improve efficiency, the coupling of the optical fibers used to sample the object and guide the light into the spectrograph was optimized in the laboratory. This investigations showed that an increase of the coupling efficiency by about 20 percent is possible by using immersion coupling between fibers and lenses.

In this thesis I focus mainly in studying the process of star formation in both high redshift, and local star forming galaxies, by using an observational technique called integral field spectroscopy (IFS). Although these investigations are aimed at studying the star formation properties of these objects, throughout this work I will also discuss the geometric, kinematic, and chemical structures in the inter-stellar medium of these galaxies, which are intimately connected with the process of star formation itself. The studies presented here were conducted under the umbrella of two different projects. First, the HETDEX Pilot Survey for Emission Line Galaxies, where I have studied the properties of Ly-alpha emitting galaxies across the 2<z<4 range, with an emphasis in trying to understand the process by which Ly-alpha photons, produced in large quantities in the active star forming regions, are able to escape the ISM of these objects, allowing us to detect them in the Ly-alpha line. The second project from which results are presented here is the VIRUS-P Exploration of Nearby Galaxies (VENGA), an ongoing campaign to obtain spatially resolved spectroscopy over a broad wavelength range for large portions of the disks of 30 nearby spiral galaxies. In this thesis, the VENGA data is used to study the physical parameters that set the rate of star formation in the different environments present within galaxies in the local universe. / text

This dissertation presents a detailed analysis of the galaxy-scale strong gravitational lenses discovered by the Sloan Lens ACS (SLACS) survey, with the aim of providing new insight into the processes that affect the evolution of galaxies at intermediate and high redshift. First, we present evidence for a relationship between the supermassive black hole mass and the total gravitational mass of the host galaxy, by utilizing the fact that gravitational lensing allows us to accurately measure the inner mass density profile of early-type lens galaxies and their total masses within an aperture. These results confirm that the properties of the bulge component of early-type galaxies and the resulting supermassive black hole are fundamentally regulated by the properties of the dark matter halo. We then utilize the lensing magnification for a detailed study of the photometric properties (luminosity, size and shape) of SLACS background sources and determine the evolution of the disk galaxy luminosity-size relation since z ~ 1. A comparison of the observed SLACS luminosity-size relation to theoretical simulations provides strong evidence for mass-dependent evolution of disk galaxies since z ~ 1. Furthermore, a comparison of the SLACS luminosity-size relation to that of a non-lensing, broad-band imaging survey shows that one can probe a galaxy population that is ~ 2 magnitudes deeper by utilizing the lensing magnification. We continue the detailed study of SLACS background sources by combining the lensing magnification with diffraction-limited integral field spectroscopy to derive two-dimensional kinematic, star formation rate and metallicity distributions of gravitationally lensed galaxies at z > 0.78. Integral field spectroscopic observations of the Hα emission line properties of a SLACS source galaxy (SDSS J0252+0039), at z = 0.98, show that the lensing magnification and adaptive optics advantages can be effectively combined to derive spatially resolved kinematics and star formation rates of compact, sub-luminous galaxies. Finally, we summarize the results of this dissertation and discuss how the powerful advantages of strong gravitational lensing can be utilized to address various questions about galaxy evolution through upcoming surveys and new telescope facilities. / Graduate

We present two-dimensional (2D) maps for emission-line fluxes and ratios and kinematics for the central regions of the Seyfert galaxies NGC 4501 and NGC 3982, from optical spectra obtained with the GMOS (Gemini Multi Object Spectrograph) Integral Field Unit (IFU) at the Gemini North telescope at a spatial resolution of ≈ 50 pc for NGC4501 and ≈30 pc for NGC 3982. This maps were constructed from by fitting the emission-line profiles of Ha, [N II] ll6548,6583, [S II] ll6716,6730 e [O I] l63000 by Gaussian curves. For NGC 4501, we have also obtained measurements for the stellar kinematics by fitting the Na I l5897 °A absorption by stellar templates, using the pPXF method. Such measurements were not possible for NGC3982, due to the nondetection of absorption lines with signal-to-noise ration high enough. NGC 4501 presents extended-line emission to up to 5′′ from the nucleus with flux peak seen at the nucleus. NGC3982 also presents the emission peak at the nucleus for all lines, however it presents emission over the field of view (7′′ × 15′′). A ring of H II regions is observed in the Ha emission with a radius of 5′′ from the nucleus for this galaxy. The gas velocity fields for both galaxies present rotation pattern, being well represented by a kinematic model of rotating disk with circular orbits in the plane of the galaxy. The highest residuals (observed velocities − model) present correlations with dust structures, which can be interpreted as inflows towards the nucleus. The stellar velocity dispersion of the bulge of NGC 4501 is s⋆=150±30 kms−1, resulting in a black hole mass of MBH=3+5 −2 ×107M⊙ based on the M − s relationship. The velocity dispersion map for NGC4501 show values ranging from 50 to 150 kms−1 for the forbidden lines, while the Ha maps shows overall smaller values, with s < 100 kms−1 at all locations. The highest s values for all emission lines are observed at 2-3′′ northeast from the nucleus for NGC 4501, being co-spatial with a distortion seen in the velocity field. In NGC 3982 observed s values ranging 50 to 150 kms−1, with the highest values observed at 1′′ east from the nucleus. The electron density maps obtained from the [S II] l 6716/l6730 line ratio shows values between 100 cm−3 the nucleus to 900 cm−3 in a ring with radius 1′′ for NGC 4501 and values reaching 100 cm−3 to 3000 cm−3 for NGC 3982. / Apresentamos mapas bidimensionais (2D) para fluxos e razões de linhas de emissão e para cinemática do gás da região central das galáxias Seyferts NGC 4501 e NGC3982 a partir de espectros ópticos obtidos com a unidade de campo integral do instrumento GMOS (Gemini Multi Object Spectrograph) no telescópio Gemini Norte, com resolução espacial de ≈50 pc para NGC4501 e ≈30 pc para NGC3982. Estes mapas foram construídos a partir do ajuste de Gaussianas aos perfis das linhas de emissão de Ha, [N II] ll6548,6583, [S II] ll6716,6730 e [O I] l6300. Para NGC4501, obtivemos ainda medidas da cinemática estelar a partir do ajuste da absorção do Na I l5897 °A por templates estelares. Tais medidas não foram possíveis para NGC3982, pois não foram detectadas linhas de absorção com razão sinal ruido suficientemente alto. NGC4501 apresenta emissão estendida até 5′′ do núcleo, com pico de fluxo observado na posição nuclear. NGC3982 também apresenta pico de emissão no núcleo para todas as linhas, porém apresenta emissão em todo o campo observado (7′′ ×15′′). Observa-se um anel de regiões H II a 5′′ do núcleo para esta galáxia. Os campos de velocidades do gás para ambas as galáxias apresentam um padrão de rotação, sendo bem representados por um modelo cinemático para um disco em rotação com órbitas circulares. O mapa de resíduos (velocidades observadas − modelo) mostra correlações com estruturas de poeira, que sugerem inflows de gás em direção ao núcleo das galáxias. A dispersão e velocidade estelar para o bojo de NGC 4501 é s⋆=150±30 kms−1, que resulta em uma massa para o buraco negro supermassivo de MBH=3+5−2 ×107M⊙ utilizando a relação M − s. Os mapas de dispersão de velocidades (s) para NGC 4501 mostram valores de 50 a 150 kms−1 para linhas proibidas, enquanto que Ha apresenta valores menores, com s < 100 kms−1 em todo o campo. Os maiores valores de s para todas as linhas de emissão são observados a 2-3′′ a nordeste do núcleo, sendo co-espacial com uma distorção vista no campo de velocidades. Em NGC3982 observam-se valores de s entre 50 a 150 kms−1, com os maiores valores observados a 1′′ a leste do núcleo. Os mapas de densidades eletrônica obtidos da razão de linhas do [S II] l 6716/l6730 mostram valores entre 100 cm−3 no n´ucleo e 900 cm−3 em um anel com raio de 1′′ ao redor do núcleo para NGC4501 e valores entre 100 cm−3 e 3000 cm−3 para NGC 3982. Estes valores são comparáveis aos obtidos para outras galáxias ativas.

The viability of using a slicer based integral field spectrograph (IFS) for high contrast observations has been under scrutiny due to the belief that the one dimensional coherence that persists along the slice to the point of sampling at the detector will cause the creation of secondary speckles that will not have the same characteristics as normal speckles, thus stopping us from calibrating them out. It has also been previously assumed that a suitably low differential wavefront error when moving slice to slice was not guaranteed by design. It was for these reasons that slicer based IFSs were not selected for the current generation of planet finding instruments. As part of the EPICS (Exo Planet Imaging Camera and Spectrograph for the E-ELT) design study it was decided that slicers should be re-investigated due to results from on sky observations suggesting these limitations did not exist. The purpose of this thesis was to determine whether there was validity to the concerns mentioned above and therefore to answer the question; Would implementing a slicer based integral field spectrograph limit the achievable contrast of an instrument designed for the direct detection of exoplanets? Chapter 1 gives a brief introduction into the field of exoplanet research. Charpter 2 describes the noise limiting direct detection of exoplanets and the ways to get around it. Chapter 3 gives an overview of the two types of IFS under investigation by the EPICS consortium. Chapter 4 looks into details of the EPICS instrument and the IFS design study that came about. Chapter 5 shows simulations performed for the aim of achieving better contrasts via post processing methods and accurate data reduction as well as simulations of slicer based integral field spectrographs. Experimental tests using a slicer and a preoptics setup designed to simulate the limiting noise are described in Chapter 6. Chapter 7 looks at using SINFONI for high contrast observations and Chapter 8 details the conclusions drawn from the work presented in this thesis, as well as possible extensions to it. The work performed in this thesis dispels the concerns about the continued one dimensional coherence up to the detecter and suggests that slicer based integral field spectrographs do not inherently limit the contrast achievable; Results from experiments fit well with the requirements for EPICS to achieve its goals. Simulations also supported the idea that secondary speckle noise should not be an issue for the slicer based IFS. This means that a slicer based IFS is a viable option for the EPICS instrument.

Les supernovae de type Ia (SNe Ia) sont de puissants indicateurs de distance cosmologique. Elles sont à l'origine de la découverte de l'énergie noire dans l'univers et restent aujourd'hui la meilleure méthode pour contraindre son équation d'état. Cependant, nous ignorons toujours le phénomène exact donnant naissance à ces supernovae. Notamment, nous ne connaissons pas l'influence de l'évolution des paramètres stellaires avec le redshift sur la luminosité de ces objets et donc sur les ajustements cosmologiques. De récentes études ont mis en évidence évidence des biais environnementaux ayant un impact significatif sur les mesures des paramètres cosmologiques. Cependant, ces études analysent les hôtes des SNe Ia dans leur globalité en négligeant les variations pourtant connues des propriétés stellaires et gazeuses au sein de ces galaxies. ! Dans cette thèse je montre comment les données de spectrographie à champ intégral de la collaboration The Nearby Supernova Factory permettent l'étude de l'environnement immédiat (~kpc) de la SNe Ia. Dans une première partie, j'introduis les bases physiques et le contexte scientifique dans lesquels ma thèse s'inscrit. Dans la seconde partie, je commence par détailler les techniques d'extraction des données environnementales locales et, une fois ces données extraites, je développe la mesure du taux de formation stellaire environnant les SNe Ia à partir du signal Hα. Dans mon analyse, je montre comment les propriétés des SNe Ia, et notamment leur luminosité standardisée, dépendent de la présence de formation stellaire à proximité. Ce biais, duquel découlent les biais environnementaux précédemment évoqués, a un impact significatif sur la cosmologie. En se basant sur les évolutions des propriétés stellaires des galaxies, je construit un modèle d'évolution de la luminosité moyenne des SNe Ia en fonction du redshift pour estimer cet impact; les données de la littérature semblent confirmer mes hypothèses. Ces résultats ont été publiés dans le journal européen Astronomy & Astrophysics (Rigault et al. 2013). Dans une troisième partie, je présente des analyses supplémentaires sur l'environnement local des SNe Ia et je suggère de nouvelles approches. ! Cette thèse a mis en évidence un biais environnemental important sur les propriétés des SNe Ia que seule l'analyse locale permet d'aborder. Cette découverte est une étape importante dans la compréhension de ces objets et dans l'amélioration de leur utilisation cosmologique / Type Ia supernovae (SNe Ia) are powerful cosmological distance indicators. They were key tools for the discovery of the accelerating expansion of the Universe and today they remain the strongest demonstrated technique for measuring the dark-energy equation of state. However, a major issue remains: despite decades of study, their progenitors are as yet undetermined. Notably, we still ignore the influence of the redshift-evolution of stellar properties on the absolute luminosity of the SNe Ia and therefore on the fitted cosmological parameters. Recent studies have highlighted potential biases correlated with the global properties of their host galaxies, large enough to induce systematic errors into cosmological measurements if not properly treated. However, those studies analyse hosts of Type Ia supernovae globally thus neglecting the known stellar and gas property variations across galaxies. ! In this thesis, I show how integral field spectroscopy data from the Nearby Supernova Factory allow the study of the local environment of the SNe Ia (~kpc). In the first part of this document, I introduce the physical principals and the scientific context of this work. In a second part, I start by detailing the technical extraction tools developed in order to extract the local host properties. Then, I show how one could measure the star formation activity in the SN vicinity from those data. I focus the analysis on this star formation activity and notably I show how the SNe Ia properties -- particularly their standardised Hubble residuals -- depend on the local host environment, which corresponds to a significant cosmological bias. I finish this second part by introducing a simple model based on the known evolution of the galactic star formation activity. This model enables me to estimate the potential influence of the aforementioned environmental bias on cosmology. I also show that this model can be tested using public data and a first analyses tend to confirm our hypotheses. Those results have been published in Astronomy & Astrophysics (Rigault et al. 2013). The third and last part of the document introduces new approaches and future work perspectives. ! In this thesis, I have highlighted significant environmental biases in SNe Ia properties, thanks to the local approach. However, those biases are less an issue for the cosmological analyses using Type Ia supernovae than a new opportunity to improve them as cosmological probes. ! This Document is written in French. The figures are in English

Spatially-resolved studies of nearby star-forming galaxies are essential to understand various physical and chemical phenomena at play in the interstellar medium in the galaxies, and consequently to obtain a comprehensive picture of galaxy formation and evolution. In this thesis, I perform spatially-resolved analyses of chemical abundances and star-formation in nearby star-forming galaxies - blue compact dwarf galaxies (BCDs) and spiral galaxies. I map various properties of H II regions and the surrounding gas within three BCDs, using integral field spectroscopic (IFS) data from the Gemini Multi-Object Spectrograph-North. While answering questions related to chemical homogeneity, ionisation mechanisms and stellar populations within BCDs, I address more profound issues, which go beyond the characterisation of studied BCDs and aim to explain global phenomena with broader implications. The BCD NGC 4449 hosts a metal-poor central star-forming region, which I explain by various scenarios related to the interplay between star-formation, metal-distribution and gas dynamics within galaxies. The BCD NGC 4670 shows an unusual negative relationship between the nitrogen-to-oxygen ratio and oxygen abundance at spatially-resolved scales. I explore this relation with chemical evolution models and by comparison to other star-forming galaxies and suggest that nitrogen enrichment, variations in star-formation efficiency or hydrodynamical effects may be responsible for the observed relation. For another BCD, SBS 1415+437, the spatially-resolved abundances on average agree with the integrated abundance, implying that low-redshift spatially-resolved results may be directly compared with unresolved high-redshift results. I study spiral galaxies to address long-standing issues related to the reliability of metallicity calibrators and the Schmidt Law of star-formation. Using IFS data of twenty-four spiral galaxies taken with the Multi-Unit Spectroscopic Explorer, I find that the current strong-line metallicity calibrators for H II regions are unsuitable for regions dominated by diffuse ionised gas (DIG). I devise new recipes for estimating the metal-content of the DIG. For another set of nine spiral galaxies, I use multi-wavelength data to show that the spatially-resolved Schmidt relation is very sensitive to the consideration of diffuse background, which is a component unrelated to the current star-formation. Removal of this component from the SFR tracers and the atomic gas results in similar local and global Schmidt relation. To conclude, the spatially-resolved analyses presented in this thesis have led to discoveries and further questions, which I will address in my ongoing and future works.