The use of background quasars provides a powerful tool to probe the cool gas in the circumgalactic medium of foreground galaxies. Here, we present new observations with SINFONI and X-Shooter of... Show moreThe use of background quasars provides a powerful tool to probe the cool gas in the circumgalactic medium of foreground galaxies. Here, we present new observations with SINFONI and X-Shooter of absorbing-galaxy candidates at z = 0.7-1. We report the detection with both instruments of the Hα emission line of one sub-damped Lyman α (sub-DLA) at zabs = 0.941 87 with log N(H I) = 19.38^{+0.10}_{-0.15} towards SDSS J002133.27+004300.9. We estimate the star formation rate: SFR = 3.6 ± 2.2 M⊙ yr-1 in that system. A detailed kinematic study indicates a dynamical mass Mdyn = 109.9±0.4 M⊙ and a halo mass Mhalo = 1011.9±0.5 M⊙. In addition, we report the [O II] detection with X-Shooter of another DLA at zabs = 0.7402 with log N(H I) = 20.4 ± 0.1 towards Q0052+0041 and an estimated SFR of 5.3 ± 0.7 M⊙ yr-1. Three other objects are detected in the continuum with X-Shooter but the nature and redshift of two of these objects are unconstrained due to the absence of emission lines, while the third object might be at the redshift of the quasar. We use the objects detected in our whole N(H I)-selected SINFONI survey to compute the metallicity difference between the galaxy and the absorbing gas, δ _{H I}(X), where a positive (negative) value indicates infall (outflow). We compare this quantity with the quasar line-of-sight alignment with the galaxy's major (minor) axis, another tracer of infall (outflow). We find that these quantities do not correlate as expected from simple assumptions. Additional observations are necessary to relate these two independent probes of gas flows around galaxies. Show less
This thesis focus on the study of the Interstellar Medium (ISM) of the Milky Way and consists of two parts: in the first one we present a study of the dust properties in HII regions and their... Show moreThis thesis focus on the study of the Interstellar Medium (ISM) of the Milky Way and consists of two parts: in the first one we present a study of the dust properties in HII regions and their surrounding PDRs. We focus our studies on two compact HII regions: W3(A) and the Orion Nebula (Chapters 2 and 3, respsectively). Using SOFIA/FORCAST observations, we determine the properties of dust in the ionized gas, their surrounding PhotoDissociation Regions and their parent molecular clouds. One of the most important conclusions of this thesis is that the grain growth can affect the dust size distribution in regions of massive star formation. The large amount of archival data available for Orion allow us to study other important phenomena related to dust in this region, such as the photoelectric heating effect and Lyman alpha heating. The second part of this thesis presents theoretical studies of the properties of the cold neutral medium (CNM) using carbon radio recombination lines (CRRL). Chapters 4 and 5 consists on the complete theory of CRRLs from the level population equation to the radiative transfer equation. Using these models and observations of CRRLs the physical parameters of the CNM can be determined. Show less