La diffusion élastique de protons sur les noyaux halo 6He et 8He a été réalisée en cinématique inverse aux énergies voisines de 700 MeV/u dans le but d'étendre les mesures de la section efficace différentielle déjà existantes à la région de haut moment transféré couvrant le premier minimum de diffraction. Pour cela, une cible d'hydrogène liquide pur a été conçue et utilisée pour la première fois, ce qui a permis, par comparaison avec les cibles classiques à base de composés C-H, d'obtenir des données de bonne qualité avec un faible niveau de bruit de fond. Les données précédentes, limitées à la région de faible moment transféré, sont sensibles notamment à la taille globale du noyau considéré et à la partie périphérique de la densité de distribution de la matière nucléaire ce qui nous a amené à nous interesser a la partie interne des noyaux halo ou plus précisément leur “coeur”. Les données obtenues et présentées dans ce travail permettent, à travers une détermination plus précise des densités de distribution, de jeter une lumière nouvelle sur cette partie et de comprendre mieux la structure du coeur a dans 6,8He. Plusieurs modèles microscopiques peuvent ainsi être testés. Les densités de distributions calculées à partir de ces modèles sont utilisées pour déduires des sections efficaces différentielles qui sont à leur tour comparées avec les données présentes.

Les systemes de raies d'absorption observes a haute resolution dans le spectre des quasars sont des outils puissants pour etudier le gaz baryonique dans l'Univers et son evolution. Tandis que les nuages de gaz diffus du milieu intergalactique, la foret Lyman-alpha, dominent la densite de masse des baryons a grand decalage spectral, les systemes d'absorption Lyman-alpha lorentziens de grandes densites de colonne en hydrogene neutre dominent la densite de masse du gaz neutre a tout decalage spectral. Ces derniers sont probablement associes a des etapes-cles de la formation et de l'evolution des galaxies. Dans cette these, je presente des travaux dont l'objectif est de mieux cerner les proprietes physiques et de contraindre la nature des systemes lorentziens. Apres une introduction et une revue detaillee de nos connaissances dans le domaine, je decris ma propre analyse des abondances chimiques et de la cinematique du gaz neutre a grand decalage spectral. Je fais ensuite le lien entre ces objets et l'identification optique des galaxies responsables de l'absorption a decalage spectral intermediaire en etudiant plus particulierement l'histoire nucleosynthetique du gaz et la possibilite de l'existence de poussieres a z_abs plus petit que 1.7. L'application des techniques de la spectroscopie integrale de champ m'a en outre permis de rechercher l'emission Lyman-alpha des regions de formation d'etoiles associees aux systemes lorentziens de decalages spectraux les plus grands, emission que j'interprete dans le cadre de plusieurs modelisations originales. La derniere partie de la these est dediee au projet d'etude de l'association de la foret Lyman-alpha avec les grandes structures et les halos galactiques de notre Univers local, et je presente dans ce contexte les resultats d'un releve efficace de quasars brillants situes a l'arriere-plan de l'amas de galaxies de Coma.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 134-137).

Flat cosmology with collisionless cold dark matter (CDM) and cosmological constant ([Lambda]CDM cosmology) may have some problems on small scales, even though it has been very successful on large scales. We study the effect of Self-Interacting Dark Matter (SIDM) hypothesis on the density profiles of halos. Collisionless CDM predicts cuspy density profiles toward the center, while observations of low mass galaxies prefer cored profiles. SIDM was proposed by Spergel & Steinhardt [161] as a possible solution to this cuspy profile problem on low-mass scales. On the other hand, observations and collisionless CDM agree on mass scales of galaxy clusters. It is also known that the SIDM hypothesis would contradict with X-ray and gravitational lensing observations of cluster of galaxies, if the cross section were too large. Our final goal is to find the range of SIDM scattering cross section models that are consistent with those astrophysical observations in two different mass scales. There are two theoretical approaches to compute the effect of self-interacting scattering -- Gravitational N-body simulation with Monte Carlo scattering and conducting fluid model; those two approaches, however, had not been confirmed to agree with each other. We first show that two methods are in reasonable agreement with each other for both isolated halos and for halos with realistic mass assembly history in an expanding [Lambda]CDM universe; the value of cross section necessary to have a maximally relaxed low-density core in [Lambda]CDM is in mutual agreement. We then develop a semianalytic model that predicts the time evolution of SIDM halo. Our semianalytic relaxation model enables us to understand how a SIDM halo would relax to a cored profile, and obtain an ensemble of SIDM halos from collisionless simulations with reasonable computational resources. We apply the semianalytic relaxation model to CDM halos, and compare the resulting statistical distribution of SIDM halos with astrophysical observations. We show that there exists a range of scattering cross sections that simultaneously solve the cuspy core problem on low-mass scales and satisfy the galaxy cluster observations. We also present that other potential conflicts between [Lambda]CDM and observations could be resolved in Part II and III. / text

In this thesis we push forward techniques to learn about the large scale structure formation of the universe. The approach is from theory, observations and simulations. From theory we study the growth of four non standard cosmological models: DGP model, Cardassian model, Chaplygin gas model and Coupled Quintessence model. From observations we look at the ISW effect by means of the cross-correlation between CMB maps and galaxy survey. From a compilation of data we contrain the cosmological parameters and give new evidence of dark energy. We also introduce a new method to compute errors in configuration space and compare it with other methods in the literature. This method takes into account the geometry of the suveys and it is shown to give accurate results at large angles. In this thesis we also use large dark matter simulations to study the clustering and the local halo bias model. KEY WORDS: large scale structure, structure formation, dark energy, halo bias / CATALÀ:En aquesta tesi estudiem la formació d'estructures a gran escala de l'univers apoximant-nos-hi des de la teoria, les observacions i les simulacions. Respecte la teoria estudiem el creixement d'estructures en quatre models no estàndards: el model DGP, el model Cardassian, el model de gas de Chaplygin i el model de Quintessècia acoplada. De les observacions estudiem la formació d'estructura a partir de correlacions entre mapes de galàxies amb mapes del CMB, les quals mesuren l'efecte ISW. A partir d'una compilació que d'aquestes mesures restringim els paràmetres cosmològics i mostrem nova evidència de l'energia fosca. També introduim un nou mètode per a calcular els errors de les correlacions en l'espai de configuració. Comparem aquest mètode amb d'altres i mostrem que estima bé els errors a angles grans, doncs tenim en compte l'area del cel observada. Finalment utilitzem simulacions de matéria fosca per estudiar el clustering i el model de bias local. / RESUMEN CASTELLANO:En esta tesis estudiamos la formación de estructura en el universo en las vertientes teórica, observacional y con simulaciones. Respeto a la teoria estudiamos el crecimiento de estructuras en cuatro modelos no estándares: el modelo DGP, el modelo Cardassian, el modelo de gas de Chaplygin y el modelo de Quintessencia acoplado. Respecto a las observaciones estudiamos la formación de estructura a partir de las correlaciones entre el CMB y mapas de galaxias, las cuales miden el efecto ISW. A partir de una compilación de estas medidas restringimos los parámetros cosmológicos dando nueva evidencia de la energía oscura. También introducimos un nuevo método para el cálculo de errores en espacio de configuración y mostramos, al compararlo con otros, que estima bien los errores a grandes ángulos puesto que tenemos en cuenta la geometria de área observada. Finalmente, utilizando simulaciones de materia oscura, estudiamos el clustering y el modelo de bias local. PALABRAS CLAVE: Estructura a gran escala, energia oscura, bias en halos, formación de estructura.

We present new Chandra observations of the outer halo of the giant elliptical galaxy NGC 4472 (M49) in the Virgo Cluster. The data extend to 130 kpc (28'), and have a combined exposure time of 150 ks. After identifying optical counterparts using the Next Generation Virgo Cluster Survey to remove background active galactic nuclei and globular cluster (GC) sources, and correcting for completeness, we find that the number of field low-mass X-ray binaries (LMXBs) per unit stellar V-band light increases significantly with the galactocentric radius. Because the flux limit of the complete sample corresponds to the Eddington limit for neutron stars in NGC 4472, many of the similar to 90 field LMXBs in this sample could host black holes. The excess of field LMXBs at large galactocentric radii may be partially caused by natal kicks on black holes and neutron stars in binary systems in the inner part of the galaxy. Furthermore, because the metallicity in the halo of NGC 4472 strongly decreases toward larger galactocentric radii, the number of field LMXBs per unit stellar mass is anticorrelated with metallicity, opposite to what is observed in GCs. Another way to explain the spatial distribution of field LMXBs is therefore a reversed metallicity effect, although we have not identified a mechanism to explain this in terms of stellar and binary evolution.

We present the survey strategy and early results of the "Satellites Around Galactic Analogs" (SAGA) Survey. The SAGA. Survey's goal is to measure the distribution of satellite galaxies around 100 systems analogous to the Milky Way down to the luminosity of the Leo I dwarf galaxy (M-r < -12.3). We define a Milky Way analog based on K-band luminosity and local environment. Here, we present satellite luminosity functions for eight Milky-Way-analog galaxies between 20 and 40. Mpc. These systems have nearly complete spectroscopic coverage of candidate satellites within the projected host virial radius down to r(o) < 20.75 using low-redshift gri color criteria. We have discovered a total of 25 new satellite galaxies: 14. new satellite galaxies meet our formal criteria around our complete host systems, plus 11 additional satellites in either incompletely surveyed hosts or below our formal magnitude limit. Combined with 13 previously known satellites, there are a total of 27 satellites around 8 complete Milky-Way-analog hosts. We find a wide distribution in the number of satellites per host, from 1 to 9, in the luminosity range for which there are 5 Milky Way satellites. Standard abundance matching extrapolated from higher luminosities predicts less scatter between hosts and a steeper luminosity function slope than observed. We find that the majority of satellites (26 of 27) are star-forming. These early results indicate that the Milky Way has a different satellite population than typical in our sample, potentially changing the physical interpretation of measurements based only on the Milky Way's satellite galaxies.

We report the first detection of extended neutral hydrogen (H I) gas in the interstellar medium (ISM) of a massive elliptical galaxy beyond z similar to 0. The observations utilize the doubly lensed images of QSO HE 0047-1756 at z(QSO) = 1.676 as absorption-line probes of the ISM in the massive (M-star approximate to 10(11) M-circle dot) elliptical lens at z = 0.408, detecting gas at projected distances of d = 3.3 and 4.6 kpc on opposite sides of the lens. Using the Space Telescope Imaging Spectrograph, we obtain UV absorption spectra of the lensed QSO and identify a prominent flux discontinuity and associated absorption features matching the Lyman series transitions at z = 0.408 in both sightlines. The H I column density is log N(H I)= 19.6-19.7 at both locations across the lens, comparable to what is seen in 21 cm images of nearby ellipticals. The H I gas kinematics are well-matched with the kinematics of the Fe II absorption complex revealed in ground-based echelle data, displaying a large velocity shear of approximate to 360 km s(-1) across the galaxy. We estimate an ISM Fe abundance of 0.3-0.4 solar at both locations. Including likely dust depletions increases the estimated Fe abundances to solar or supersolar, similar to those of the hot ISM and stars of nearby ellipticals. Assuming 100% covering fraction of this Fe-enriched gas, we infer a total Fe mass of M-cool(Fe) similar to (5-8) x 10(4) M-circle dot in the cool ISM of the massive elliptical lens, which is no more than 5% of the total Fe mass observed in the hot ISM.

El objetivo de esta investigación fue evaluar ”in vitro” la actividad antibacteriana de dos pastas: 3 Mix-MP y Calen PMCC® como medicación intraconducto en un biofilm formado por 3 cepas: Porphyromona Gingivalis, Enterococcus Faecalis y Peptostreptococcus Anaerobius, presentes en Periodontis apical crónica; se utilizaron 32 piezas dentarias (premolares) a las cuales se les aplicó el mismo protocolo: fueron instrumentadas con sistema Mtwo hasta la lima 40.04, luego 22 piezas fueron seccionadas mesiodistalmente y 10 no seccionadas, fueron esterilizadas y contaminadas manteniéndolas en caldo BHI vitaminado por un lapso de 7 días. El proceso se dividió en 2 fases: en la primera fase se usaron 12 piezas seccionadas; a las que se les hizo el raspado en toda la superficie sembrándose en Agar Shaedler por 7 días; luego se realizaron 4 pozos de 5mm de diámetro por cada placa donde se colocaron las pastas de 3Mix-MP, Calen PMCC®, Hidróxido de calcio con suero fisiológico (control positivo) y glicerina (control negativo) dichas placas se incubaron por 7 días en anaerobiosis y se procedió a la lectura de los halo de inhición bacteriana. En la segunda fase siguiendo el protocolo anterior se usaron las 20 piezas restantes (10 seccionadas y 10 no seccionadas a las que se les colocó la pasta 3Mix-MP, la pasta Calen PMCC®, hidróxido de calcio con suero fisiológico (control positivo), se realizó el raspado y sembrado en agar shaedler manteniéndolo en anaerobiosis por 7 días para finalmente realizar la lectura de las unidades formadoras de colonias (ufc) presentes. El resultado observado con respecto a los halos de inhibición mostró que fue mayor para la pasta 3Mix - MP (40mm.) en comparación con la pasta Calen PMCC® (7mm.), con respecto a la lectura no se pudo recuperar colonias en las muestras de 3Mix-MP a diferencia de Calen PMCC® que se obtuvo 04 ufc.; concluyéndose que la pasta 3Mix-MP tiene mayor efecto antibacteriano como medicación intraconducto frente a la pasta Calen PMCC®. / Tesis

The circumgalactic medium (CGM) is thought to contain the massive reservoir of gas exchanged over the course of galactic evolution, including the fuel for future star formation and the remnants of a galaxy’s merger history. Models and observations suggest that the CGM has a very low density, and faint optical or UV emission from this gas is exceedingly difficult to detect. This thesis is a combination of simulations, instrumentation and observations aimed at ultimately understanding the distribution and kinematics of ionized gas in the CGM. We present a suite of small-box hydrodynamic simulations created to study the interaction between smooth gas inflow and supernovae-driven outflow at the disk-halo interface where the galactic disk transitions into the CGM. They track the fate and kinematic evolution of gas accreting onto the galactic disk and find evidence of partial mixing with the enriched outflow. We use equilibrium photoionization models to create mock surface brightness maps of Ha and OVI emission. These observables motivate the need for new instrumentation and in suit, we present the newly commissioned Circumgalactic Ha Spectrograph (CHaS): a custom integral field unit (IFU) spectrograph tailored to detect low-surface brightness optical emission in the low-redshift universe. CHaS is deployed in the focal plane of the MDM Observatory Hiltner 2.4-meter telescope, conducting wide-field (10' x 10') spectral imaging with a competitive survey speed proportional to the high instrument grasp. A microlens array segments the field of view into > 60,000 spectra with a spatial resolution of 2.6'' and a resolving power of R ~ 10,000. Accordingly, CHaS is capable of resolving structure on scales less than 1 kpc (at 10 Mpc) and distinguishing emission lines separated by less than 40 km/s. As designed, a 50-100h exposure with CHaS would be the deepest H-alpha image and velocity field ever obtained, reaching a surface brightness of a few mR on scales of a few arcmin. Shorter, hour-long integrations with CHaS reveal a detailed map of the denser interstellar medium and bright emission at the disk-halo interface. We present results for three early commissioning targets: NGC 4631, NGC 7331 and NGC 1068, including high-resolution velocity maps and detections of new extended emission line regions far into the halo. We report a previously unnoted ribbon of ionized gas around NGC 1068, extending tens of kpc from the galactic disk beyond the known outer filamentary structure. Ongoing observations will provide a deeper probe of ionized gas far into the CGM of many nearby galaxy targets, detecting faint extended emission and mapping the velocity of ionized gas beyond the disk.