Thesis (Ph.D.)--Ohio University, August, 2004. / Title from PDF t.p. Includes bibliographical references (p. 173-185)

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We present a study of high-resolution long-slit spectra of the Narrow-Line Regions (NLRs) of NGC 4151 (a Seyfert 1 galaxy) and NGC 1068 (a Seyfert 2 galaxy) obtained with the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope (HST). The spectra were retrieved from the Multimission Archive at Space Telescope (MAST) and were obtained from five and seven orbits of HST time resulting in five and seven parallel slit configurations at position angles of 52 degrees and 38 degrees for NGC 4151 and NGC 1068 respectively. The spectra have a spatial resolution of 0.2 arcsecond across and 0.1 arcsecond along each slit. Observations of [O III] emission from the NLRs were made using the medium resolution G430M grating aboard HST. The spectral resolving power of the grating, R~9000, resulted in the detection of multiple kinematic components of the [O III] emission line gas along each slit. Radial velocities of the components were measured using a Gaussian fitting procedure. Biconical outflow models were generated to match the data and for comparison to previous models done with lower dispersion observations. The general trend is an increase in radial velocity roughly proportional to distance from the nucleus, followed by a linear decrease after roughly 100 pc. This is similar to that seen in other Seyfert galaxies, indicating common acceleration and deceleration mechanisms. The full-width at half-maximum (FWHM) of the emission lines reaches a maximum of 1000 km/s near the nucleus, and generally decreases with increasing distance to about 100 km/s in the extended narrow-line region (ENLR), starting at about 400 pc from the nucleus. In addition to the bright emission knots, which generally fit our model, there are faint high velocity clouds that do not fit the biconical outflow pattern of our kinematic model. A comparison of our observations with high-resolution radio maps shows that the kinematics of the faint NLR clouds may be affected by the radio lobes that comprise the inner jet. However, the bright NLR clouds show a smooth transition across the radio knots in radial velocity and velocity dispersion plots and remain essentially undisturbed in their vicinity, indicating that the radio jet is not the principal driving force on the outflowing NLR clouds. A dynamical model was developed for NGC 1068; it includes forces of radiation pressure, gravity, and drag due an ambient medium, simultaneously acting on the NLR clouds. The velocity profile from this model was too steep to fit the data, which show a more slowly increasing velocity profile. Gravity alone was not able to slow down the clouds but with the drag forces included, the clouds could slow down, reaching systemic velocities at distances that depend on the column densities of the NLR gas and density of the intercloud medium. A biconical model using the geometric parameters from our kinematic fit, and the velocity law from the dynamic fit, was used to match the data. The resulting dynamic model represented a poor fit to the data, indicating the need for additional dynamical considerations.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / We have mapped emission-line flux distributions and ratios as well as the gaseous kinematics of the inner 450 pc radius of the Seyfert galaxy Mrk 766 using integral field near-IR J- and Kl-band spectra obtained with the Gemini North instrument NIFS at a spatial resolution of ≈60 pc and velocity resolution of ≈40 kms−1. Emission-line flux distributions in Pa β and Brγ extend to ≈300 pc from the nucleus in all directions, while the [Fe II] emission is extended to a similar distance but mostly along PA≈130◦. The coronal lines traced by [S IX] are resolved, presenting emission up to ≈150 pc from the nucleus. The molecular H2 gas emission is extended also to ≈300 pc from the nucleus but along PA≈50º, approximately perpendicularly to the orientation of the [Fe II] emission. The H2 gas has an excitation temperature Texc = 2360±45K and its emission is dominated by thermal processes, mainly due X-ray heating by the active nucleus. The [Fe II] emission seems also to be produced by these thermal processes, but with an important contribution from shocks, as evidenced by the correlation between enhanced [Fe II]/[P II] line ratios, the [Fe II] velocity dispersion and the radio structure. The gas velocity field is dominated by rotation, and the fit of a circular model gives a position angle of 59º for the line of nodes, which is the approximate orientation of the extended H2 emission. This fact, combined with the low H2 velocity dispersion close to the velocity resolution of the data supports a location of the H2 emitting gas in the galaxy plane, and its association with the feeding of the supermassive black hole. There is about 103 M⊙ of hot H2, implying ≈109 M⊙ of cold molecular gas in the inner 450 pc radius. On the other hand, the higher velocity dispersion (150 kms−1) for [Fe II] to the southeast of the nucleus, and the presence of both blueshifts and redshifts in the channel maps at the corresponding locations, supports the presence of an outflow to the southwest with an axis lying close to the plane of the sky. The ionized gas outflow rate is estimated to be 2.18 M⊙ yr−1, and the power of the outflow 0.011 Lbol. The distinct flux distributions and kinematics of the H2 and [Fe II] emitting gas, with the first more restricted to the plane of the galaxy and in rotation and the second related with the radio jet and in outflow are common characteristics of 8 Seyfert galaxies (ESO428-G14, NGC4051, NGC7582, NGC4151, Mrk 1066, Mrk 1157, Mrk 79 and Mrk 766) we have studied so far using similar integral-field observations and 2 others (Circinus and NGC2110) using long-slit observations. These results support the conclusion that the H2 emission is tracer of the AGN feeding, while the [Fe II] is a tracer of its feedback. / Mapeamos as distribuições de fluxos de linhas de emissão e suas razões bem como a cinemática do gás nos 450 pc centrais da galáxia Seyfert Mrk 766 usando espectroscopia de campo integral (IFS) na região do infravermelho próximo nas bandas J e Kl obtidas com o instrumento NIFS do telestcópio Gemini-Norte com uma resolução espacial de ≈ 60 pc e resolução espectral de ≈ 40 km s−1. As distribuições de fluxos das linhas de emissão de Paβ e Brγ se estendem até ≈ 300 pc do núcleo em todas as direções, enquanto a emissão do [Fe II] se estende até uma distância similar, porém, mais concentrada ao longo do PA≈ 130º. As linhas coronais traçadas pelo [S IX] são resolvidas, apresentando emissão até ≈ 150 pc do núcleo. A emissão do H2 molecular é estendida também a ≈ 300 pc do núcleo, mas, ao longo do PA ≈ 50º, aproximadamente perpendicular a orientação da emissão do [Fe II]. O gás H2 tem uma temperatura de excitação Texc = 2360 ±45 K e sua emissão é dominada por processos térmicos, principalmente devido a aquecimento do gás por raios-X provenientes do núcleo ativo. A emissão do [Fe II] também parece ser produzida por esses processos térmicos, mas com uma importante contribuição dos choques, assim como evidenciado pela razão [Fe II]/[P II] e por aumentos na dispersão de velocidades associados com o jato rádio. e a estrutura rádio. O campo de velocidades do gás é dominado por rotação, e o ajuste de um modelo de órbitas circulares no plano da galáxia nos dá um ângulo de posição de 59º para a linha dos nodos, o que parece ser aproximadamente a orientação da elongação da emissão do H2. Este fato, combinado com a baixa dispersão de velocidades do H2 é consistente com emissão de gás localizado no plano da galáxia e sua associação com a alimentação do buraco negro supermassivo. Há aproximadamente 103 M⊙ de H2 quente, implicando em ≈ 109 M⊙ de gás molecular frio no interior dos 450 pc centrais. Por outro lado, a maior dispersão de velocidades para o [Fe II] (150 km s−1) a sudeste do núcleo, e a presença tanto de blueshifts quanto redshifts nos mapas de fluxo para diferentes velocidades nas correspondentes localizações, apoiam a presença de um outflow a sudeste, orientado próximo ao plano do céu. A taxa de outflow de gás ionizado é estimada em 2.18 M⊙ ano−1 e sua potência em 0.011 Lbol. As distintas distribuições de fluxo e cinemática do H2 e do [Fe II], com o primeiro mais restrito ao plano da galáxia e em rotação e o segundo relacionado com o jato rádio e em outflow são características comuns de 8 galáxias Seyferts (ESO 428-G14, NGC4051, NGC 7582, NGC 4151, Mrk 1066, Mrk 1157, Mrk 79 e Mrk 766) que foram estudadas por nosso grupo até agora, usando IFS e 2 outras (Circinus e NGC 2110) usando esoectroscopia de fenda longa. Estes resultados apoiam a conclusão de que a emissão do H2 é um traçador da alimentação do núcleo ativo, enquanto o [Fe II] é um traçador de seu feedback.

We present a detailed study of mid-infrared spectroscopy and optical imaging of Seyfert galaxies with the goal of understanding the properties of astronomical dust around the central supermassive black hole and the accretion disk. Specifically, we have studied Spitzer Space Telescope mid-infrared spectra of 12 Seyfert 1.8-1.9s and 58 Seyfert 1s and 2s available in the Spitzer public archive, and the nuclear dust morphology in the central 500 pc of 91 narrow and broad-line Seyfert 1s using optical images from the Hubble Space Telescope. We have also developed visualization software to aid the understanding of the geometry of the central engine. Based on these studies, we conclude that the nuclear regions of Seyfert galaxies are fueled by dusty spirals driven by the large-scale stellar bars in the host galaxy. The accumulation of dusty gas in the central kiloparsec leads to enhanced star formation. In this case, the circumnuclear starburst and the central engine compete for dominance in the heating of the circumnuclear dust. Emission from the heated dust is most clearly seen in the mid-infrared. We find that the spectra of Seyfert 2s show the most variety in the continuum shapes due to different starburst contributions. We find that the spectra of Seyfert 2s that are devoid of starburst contribution are dominated by a single thermal component at a temperature of T ~ 170 K. We also find that the mid-IR continua of Seyfert 1.8/1.9 galaxies are more like those of starburst-dominated Seyfert 2s than Seyfert 1s, contrary to expectations. We discuss the implications of these findings in the context of the Unified Model of AGN and the secular evolution of Seyfert nuclei.

Au cours des dernières décennies, l’astronomie infrarouge a changé notre point de vue au sujet de l’évolution des galaxies, en particulier à de grandes distances. Nous avons accès à une grande variété d’informations physiques grâce au domaine spectral infrarouge. Toutefois, les limites de diffraction des instruments infrarouges et l’existence d’un grand nombre de sources font de l’identification individuelle des galaxies une tâché difficile. La première partie de cette thèse est consacrée à Résoudre le fond extragalactique infrarouge avec l’observatoire spatial Herschel, à, l’aide de simulations réalistes, correspondant aux images les plus profondes jusqu’ici obtenues en infrarouge lointain. Nous avons étudié l’origine du bruit de confusion dans les images GOODS-Herschel et résolu une partie de fond cosmique infrarouge en galaxies individuelles. De nouvelles techniques ont été développées pour prédire les flux en infrarouge lointain à partir de la connaissance préalable des positions, décalages spectraux et densités de flux des sources dans l’infrarouge moyen. Les images simulées ont été construites en utilisant les flux prédits afin d’évaluer le rôle du bruit local de confusion et d’identifier des sources individuelles. La deuxième partie de la thèse concerne l’étude de la Destruction de grains de poussières par des jets vus en radio. Nous avons étudié les effets des noyaux actifs de galaxies dans le milieu interstellaire, en particulier le mécanisme qui donne lieu à la région des raies étroites dans les galaxies de type Seyfert. Des spectres en infrarouge proche à fente longue a ont été enregistrés sur un ensemble de galaxies Seyfert de type 2 afin de mesurer les raies d’émission de ([Fe II], [P II] et Paβ) qui révèlent la destruction de poussières par les ondes de choc produites par les jets radio. Nous avons constaté que le mécanisme dominant l’ionisation près du noyau des galaxies Seyfert est le champ de rayonnement produit par l’activité du trou noir. Dans la partie extérieure de la région des raies étroites, des ondes de choc induites par des jets de radio contribuent également au budget énergétique du milieu interstellaire et à la destruction des grains de poussière. Cette thèse s’est déroulée en co-encadrement au Service d’Astrophysique du CEA-Saclay et au Département d’Astronomie de l’Université de Concepción, au Chili. / During the last decades, infrared astronomy has changed our view about the evolution of galaxies, especially at large distances. We have access to large variety of physical information in the infrared bands. However, diffraction limits of the infrared instruments and the existence of a large number of sources makes individualization of galaxies a difficult task. The first part of this thesis is entitled Resolving the Cosmic Infrared Background with the Herschel Space Observatory where, by the use of far-infrared realistic simulations of the deepest infrared images of the Universe, we have studied the origin of the confusion noise in the GOODS-Herschel images and resolved a substantive part of the Cosmic Infrared Background into individual galaxies. New techniques were developed to predict the fluxes in the far-infrared from prior knowledge in the mid-infrared. Mock images were built using those predicted fluxes to evaluate the role of local confusion noise and identify individual sources. The second part of the thesis concerns the study of the Destruction of dust grains by radio jets. We study the effects of active galactic nuclei in the insterstellar medium, in particular in the mechanism that gives rise to the narrow-line region in Seyfert galaxies. Long-slit near-Infrared spectra of a set of type-2 Seyfert galaxies were taken to measure diagnostic emission lines ([Fe II], [P II] and Paβ) that reveal the destruction of dust grains due to the shock waves produced by the radio jets. We found that the dominant mechanism of ionization close to the nuclei of the Seyfert galaxies is the radiation field produced by the back hole activity. In the outer part of the narrow-line region, shock waves induced by the radio jets also contribute to the energy budget of the interstellar medium and sputter the dust grains. This was a co-advising thesis performed in the Service d’Astrophysique CEA-Saclay and the Astronomy Department of the University of Concepción, Chile. / Durante las últimas décadas, la astronomía infrarroja ha cambiado nuestra visión sobre la evolución de galaxias, en especial revelando que a grandes distancias (z >1) las galaxias individuales son típicamente Galaxias Infrarrojas Ultraluminosas (cuyas siglas en inglés son ULIRGs por Ultraluminous Infrared Galaxies, 1012 < Lbol < 1013 L⊙). Actualmente tenemos acceso a una gran variedad de información física basada en la emisión en bandas espectrales infrarrojas (IR), radiación que en el caso de las galaxias es producida en su mayoría por granos de polvo. Sin embargo, el límite de difracción de los instrumentos infrarrojos junto con el gran número de fuentes de emisión hace de la individualización de galaxias una tarea difícil. La primera parte de esta tesis se titula Resolviendo el Fondo Cósmico Infrarrojo con el Observatorio Espacial Herschel donde, con el uso de simulaciones realistas de las imágenes más profundas del Universo, hemos estudiado el origen del ruido de confusión en las imágenes GOODS-Herschel y resuelto en galaxias individuales una parte sustantiva del Fondo Cósmico Infrarrojo. Nuevas técnicas fueron desarrolladas para predecir los flujos en el infrarrojo lejano a partir del conocimiento a priori en el infrarrojo medio. Las imágenes simuladas fueron construidas usando esos flujos predichos y con ellos evaluar el rol del ruido de confusión local así como identificar fuentes individuales. La segunda parte de la tesis trata del estudio sobre la Destrucción de granos de polvo por chorros en ondas de radio. Este proyecto que se concentró en la observación de galaxias Seyfert y ULIRGS y apunta a entender mejor el ciclo de vida del polvo al estudiar la destrucción de granos en galaxias con nucleos activos y los efectos de la actividad de estas últimas en el medio interestelar, en particular en el mecanismo que da origen a la región de líneas de emisión angostas en las galaxias Seyfert. Se obtuvo espectros infrarrojos de rendija larga de galaxias Seyfert del tipo 2 para medir líneas de emisión ([Fe II], [P II] y Paβ) las cuales revelan la destrucción de granos de polvo debido a las perturbaciones de las ondas de choque producidas por chorros detectados en ondas de radio. Hemos encontrado que el mecanismo dominante de la ionización cerca de los núcleos de las galaxias Seyfers es el campo de radiación producido por la actividad del agujero negro central. En la parte externa de la región de líneas de angostas, las ondas de choque inducidas por los chorros en radio también contribuyen al balance energético del medio interestelar y desintegran los granos de polvo. Esta fue una tesis de co-tutela llevada a cabo en el Departamento de Astronomía de la Universidad de Concepción y en el Service d’Astrophysique del Commissariat á l’Énergie Atomique (CEA), Francia