We present a study of the relation between galaxy stellar age and mass for 14 members of the z = 1.62 protocluster IRC 0218, using multiband imaging and HST G102 and G141 grism spectroscopy. Using UVJ colors to separate galaxies into star-forming and quiescent populations, we find that, at stellar masses M*>= 10(10.85)M circle dot the quiescent fraction in the protocluster is f(Q) = 1.0(-0.37)(+0.00), consistent with a similar to 2x enhancement relative to the field value, f(Q) = 0.45(-0.03)(+0.03). At masses 10(10.2)M circle dot <= M* <= 10(10.85)M circle dot, f(Q) in the cluster is f(Q) = 0.40(-0.18)(+0.20), consistent with the field value of f(Q) = 0.28(-0.02)(+0.02). Using galaxy D-n(4000) values derived from the G102 spectroscopy, we find no relation between galaxy stellar age and mass. These results may reflect the impact of merger- driven mass redistribution-which is plausible, as this cluster is known to host many dry mergers. Alternately, they may imply that the trend in f(Q) in IRC 0218 was imprinted over a short timescale in the protocluster's assembly history. Comparing our results with those of other high- redshift studies and studies of clusters at z similar to 1, we determine that our observed relation between f(Q) and stellar mass only mildly evolves between z similar to 1.6 and z similar to 1, and only at stellar masses M* <= 10(10.85) M circle dot Both the z similar to 1 and z similar to 1.6 results are in agreement that the red sequence in dense environments was already populated at high redshift, z greater than or similar to 3, placing constraints on the mechanism(s) responsible for quenching in dense environments at z >= 1.5.

Doctor of Philosophy / Department of Sociology, Anthropology, and Social Work / Patrick Akard / This study examines the mythology of rock and roll stars in film. To accomplish this the narrative structures and ideological components of films about rock stars were identified and analyzed. There were two reasons for choosing this film genre. First, these films are specifically produced for a youth-oriented audience, an age demographic making the transition to adulthood. Because of this, these films provide commentary about social institutions and cultural values about finding a place in a market-based economy that is not as clearly transparent in other genres. Second, these films deal with society across historical time periods, starting with the inception of rock and roll in the 1950s through the present time. Because they cross multiple decades it is possible to analyze how the narrative structure and content of the films change across time and how these changes reflect changes in social conditions. The narrative structure of these films were identified and analyzed following the methodology laid out by Will Wright in Sixguns and Society (1975). The five narrative structures that were identified included, in chronological order, the reconciliation plot, the personal revival plot, the personal revival plot tragedy variation, the self-destruction plot, and the rejection plot. The journey the heroes in each plot take, along with the obstacles they face and how they find their place in society, coincide with historically situated cultural values and social conditions. Film content was analyzed through assessing how binary oppositions were resolved and the core themes represented. Both components, the narrative structures and binary oppositions, changed in ways reflective of the historical context in which the films were produced and reinforced particular ideological positions about cultural values, the youth, and the marketplace. While the hero's journey took different direction within each of the identified plots, they all contained a common thread – the rock star always finds a place in society by conforming to structural conditions instead of working to alter them.

We combine state-of-the-art models for the production of stellar radiation and its transfer through the interstellar medium (ISM) to investigate ultraviolet-line diagnostics of stars, the ionized and the neutral ISM in star-forming galaxies. We start by assessing the reliability of our stellar population synthesis modelling by fitting absorption-line indices in the ISM-free ultraviolet spectra of 10 Large Magellanic Cloud clusters. In doing so, we find that neglecting stochastic sampling of the stellar initial mass function in these young (similar to 10-100 Myr), low-mass clusters affects negligibly ultraviolet-based age and metallicity estimates but can lead to significant overestimates of stellar mass. Then, we proceed and develop a simple approach, based on an idealized description of the main features of the ISM, to compute in a physically consistent way the combined influence of nebular emission and interstellar absorption on ultraviolet spectra of star-forming galaxies. Our model accounts for the transfer of radiation through the ionized interiors and outer neutral envelopes of short-lived stellar birth clouds, as well as for radiative transfer through a diffuse intercloud medium. We use this approach to explore the entangled signatures of stars, the ionized and the neutral ISM in ultraviolet spectra of star-forming galaxies. We find that, aside from a few notable exceptions, most standard ultraviolet indices defined in the spectra of ISM-free stellar populations are prone to significant contamination by the ISM, which increases with metallicity. We also identify several nebular-emission and interstellar-absorption features, which stand out as particularly clean tracers of the different phases of the ISM.

La variété de galaxies dans le Groupe Local rend possible l'étude du milieu interstellaire et de la formation d'étoiles dans des conditions différentes de celles trouvées dans la Voie Lactée, tout en conservant une grande résolution spatiale grâce à leur proximité. Nous avons étudié le milieu interstellaire de deux galaxies du Groupe Local, M33 et NGC6822, dont les métallicités sont inférieures d'un facteur 2 à 3 à celle du soleil et qui sont respectivement dix fois et cent fois moins lumineuses que la Voie Lactée. Nos observations de la transition J=2->1 du monoxyde de carbone, avec une résolution suffisante pour résoudre les nuages moléculaires géants, fournissent la première carte du milieu moléculaire de NGC6822 et la cartographie de M33 avec la meilleure combinaison de résolution et de sensibilité. Nous présentons également une cartographie haute résolution du milieu atomique de M33 à partir d'une mosaïque intérférométrique dans la raie à 21cm de l'ensemble du disque de la galaxie. Combinées avec des données allant de l'ultraviolet à l'infrarouge lointain, ces observations permettent l'étude du milieu interstellaire et de la formation d'étoiles à des échelles allant du nuage individuel à la galaxie dans son ensemble. Ces deux objets, chimiquement jeunes, semblent convertir l'hydrogène moléculaire en étoiles plus rapidement que les grandes galaxies spirales comme la Voie Lactée. Est-ce à rapprocher du taux élevé de formation d'étoiles dans les galaxies de l'univers plus jeune (z~0.5-1), également riches en gaz et bleues comme M33 et NGC6822 ? Un soin particulier a été apporté pour tenter de mesurer la masse de dihydrogène, difficile dans ce type d'objet, à l'échelle de la galaxie ainsi qu'à l'échelle du nuage. Une méthode d'identification automatique et de mesure des propriétés physiques des nuages moléculaires géants a permis d'obtenir, dans le cas de M33, le plus grand catalogue de nuage moléculaires dans une galaxie extérieure. Il en résulte que les nuages de M33 et de NGC 6822 ont, en moyenne, une largeur de raie plus faible, pour une taille donnée, que les nuages de la Voie Lactée. Dans M33, la fraction de petits nuages augmente significativement avec le rayon galactocentrique. Au moins un sixième des nuages moléculaires géants ne sont pas associés à de la formation stellaire (détectée) mais nous n'avons pas identifié de caractéristiques physiques particulières pour ces nuages. / The variety of galaxies in the Local Group enables the study of the interstellar medium and star formation under conditions different from those found in the Milky Way, while retaining a good spatial resolution due to their proximity. We have studied the interstellar medium of two Local Group galaxies, M33 and NGC6822, that have metallicities 2 to 3 times less than solar and are respectively 10 and 100 times less luminous than the Milky Way. Our large scale observations of the CO(2-1) transition, with a resolution sufficient to resolve giant molecular clouds, provide the the first molecular gas map of NGC6822 and the M33 map with the best combination of resolution and sensitivity. We also present a high resolution map of the atomic gas from an interferometric mosaic of M33's disk through the 21cm hydrogen line. Combining these observations with data ranging from ultraviolet to far infrared, we study the interstellar medium and star formation on scales ranging from individual clouds to the whole galaxy. These two chemically young objects appear to be converting molecular hydrogen into stars at a faster rate than in large spirals like the Milky Way. Can this be linked to the high star formation rate in galaxies of the earlier universe (z~0.5-1) which were bluer and gas rich like M33 and NGC6822 ? We have taken particular care to try and measure the molecular hydrogen mass, a difficult task in such objects, at the scale both of the galaxy and of the clouds. An automated molecular cloud identification and physical property measurement has been applied to the molecular gas data, yielding, in the case of M33, the largest catalog of giant molecular clouds in an external galaxy. From this catalog, it is found that the M33 molecular clouds have, on average, a smaller line-width, for a given size, than their Galactic counterparts. In M33, the fraction of small clouds increases significantly with the galactocentric radius. At least a sixth of the giant molecular clouds are not associated with detected star formation but we have not identified any particular physical characteristics for these clouds.

Masters of Science / The study of the faint radio universe and of its properties has recently become a very active field of research not only because of the much improved capabilities of the SKA pathfinders but also because of the need to better plan for SKA surveys. These new facilities will map large areas of the sky to unprecedented depths and transform radio astronomy into the leading technique for investigating the complex processes which govern the formation and evolution of galaxies. This thesis combines multi-wavelength techniques, highly relevant to future deep radio surveys, to study the properties of faint radio sources. The nature of the faint radio sources is presented, over a large GMRT survey area of an area of 1.2 deg2 comprising 2800 sources. Utilising multi-wavelength data we have matched 85% of the radio population to Spitzer/IRAC and obtained a redshift estimate for 63%. The redshift associations are a combination of photometric and spectroscopic redshift estimates. This study investigates several multi-wavelength diagnostics used to identify AGN, using radio, infrared, optical and x-ray data . This analysis shows that various diagnostics (from the radio through the X-ray ones) select fairly different types of AGNs, with an evidence of a disagreement in the number of AGNs selected by each individual diagnostics. For the sources with redshift we use a classification scheme based on radio luminosity, x-ray emission, BOSS/SDSS spectroscopy, IRAC colors satisfying the Donley criterion, and MIPS 24ɥm radio-loud AGN criteria to separate them into AGNs and SFGs. On the basis of this classification, we find that at least 12.5% of the sources with redshifts are AGNs while the remaining 87.5% are adopted as SFGs. We explore the nature of the classified sources through the far-infrared radio correlation. We measure a median qIR value of 2:45± 0:01 for the SFGs and qIR value of 2:27 ± 0:05 for the AGNs. The decrease in the median value of qIR for the AGNs is a result of the additional AGN component to radio emission for the AGN-powered sources and find tentative evidence of an evolution of the qIR with redshift.

Our sensitive (sigma(n) approximate to 572 nJy beam(-1)), high-resolution (FWHM theta(1/2) = 0"22 approximate to 2 kpc at z greater than or similar to 1), 10 GHz image covering a single Karl G.. Jansky Very Large Array (VLA) primary beam (FWHM circle minus(1/2) approximate to 4.'25) in the GOODS-N field contains 32 sources with S-p greater than or similar to 2 mu Jy beam(-1) and optical and/or near-infrared (OIR) counterparts. Most are about as large as the star-forming regions that power them. Their median FWHM major axis is <theta(M)>= 167 +/- 32 mas approximate to 1.2 +/- 0.28 kpc, with rms scatter approximate to 91 mas approximate to 0.79 kpc. In units of the effective radius re that encloses half their flux, these radio sizes are re approximate to 69 +/- 13 mas approximate to 509 +/- 114 pc, with rms scatter approximate to 38 mas approximate to 324 pc. These sizes are smaller than those measured at lower radio frequencies, but agree with dust emission sizes measured at mm/sub-mm wavelengths and extinction-corrected H alpha sizes. We made a lowresolution (theta(1/2) = 1."0) image with approximate to 10x better brightness sensitivity, in order to detect extended sources and measure matched-resolution spectral indices alpha(10 GHz)(1.4 GHz) 10 GHz. It contains six new sources with Sp. 3.9 mJy beam-1 and OIR counterparts. The median redshift of all 38 sources is similar to z similar to = 1.24 +/- 0.15. The 19 sources with 1.4 GHz counterparts have a median spectral index of <alpha(1.4 GHz) (10 GHz)> = -0.74 +/- 0.10 10 GHz, with rms scatter approximate to 0.35. Including upper limits on a for sources not detected at 1.4 GHz flattens the median to <alpha(1.4 GHz) (10 GHz)> greater than or similar to -0.61 10 GHz, suggesting that the mu Jy radio sources at higher redshifts-and hence those selected at higher rest-frame frequencies-may have flatter spectra. If the non-thermal spectral index is alpha(NT) approximate to -0.85, the median thermal fraction of sources selected at median rest-frame frequency approximate to 20 GHz is greater than or similar to 48%.

The Kimball methodology, often referred to as dimensional modelling, is well established in data warehousing and business intelligence as a highly successful means for turning data into information. Yet weaknesses exist in the Kimball approach that make it difficult to rapidly extend or interrelate dimensional models in complex business areas such as Health Care. This Thesis looks at the development of a methodology that will provide for the rapid extension and interrelation of Kimball dimensional models. This is achieved through the use of techniques similar to those employed in the semantic web. These techniques allow for rapid analysis and insight into highly variable data which previously was difficult to achieve. / Graduate

We present new photometric data of 11 hot Jupiter transiting exoplanets (CoRoT-12b, HATP-5b, HAT-P-12b, HAT-P-33b, HAT-P-37b, WASP-2b, WASP-24b, WASP-60b, WASP-80b, WASP-103b and XO-3b) in order to update their planetary parameters and to constrain information about their atmospheres. These observations of CoRoT-12b, HAT-P-37b and WASP-60b are the first follow-up data since their discovery. Additionally, the first near-UV transits of WASP-80b and WASP-103b are presented. We compare the results of our analysis with previous work to search for transit timing variations (TTVs) and a wavelength dependence in the transit depth. TTVs may be evidence of a third body in the system, and variations in planetary radius with wavelength can help constrain the properties of the exoplanet's atmosphere. For WASP-103b and XO-3b, we find a possible variation in the transit depths which may be evidence of scattering in their atmospheres. The B-band transit depth of HAT-P-37b is found to be smaller than its near-IR transit depth and such a variation may indicate TiO/VO absorption. These variations are detected from 2-4.6s, so follow-up observations are needed to confirm these results. Additionally, a flat spectrum across optical wavelengths is found for five of the planets (HAT-P-5b, HAT-P-12b, WASP-2b, WASP-24b and WASP-80b), suggestive that clouds may be present in their atmospheres. We calculate a refined orbital period and ephemeris for all the targets, which will help with future observations. No TTVs are seen in our analysis with the exception of WASP-80b and follow-up observations are needed to confirm this possible detection.

To eliminate uncertainties introduced by extinction by dust in the optical, we examine to what extent the radio continuum (RC) can probe star formation in dwarf galaxies. Star formation (SF) drives galaxy formation and evolution; acquiring accurate measurements of SF thus becomes crucial in order to understand galaxies. As radio technology improves further, RC surveys will probe the fainter, more quiescent regime of the radio sky. Having a robust manner by which to convert RC luminosities to star formation rate (SFR) has the potential to provide millions of independent SFR measurements out to intermediate redshifts. In order to calibrate the RC to infer SFR, the 40 dwarf galaxies that make up the LITTLE THINGS sample were chosen as the bedrock of the thesis due to the large range of galactic parameters that they cover. RC observations of these galaxies were taken with the VLA between L- and Ka-band (1-33GHz) using the B-, C-, and Darrays, yielding images with 3-10" resolution and rms noise levels between 3 and 15 μJy beam⁻¹. On a global scale, 27 out of the 40 dwarf galaxies exhibited RC emission above the detection threshold, 17 of which were new RC detections. The general picture is an interstellar medium (ISM) largely void of RC emission, interspersed by isolated pockets of RC associated with SF regions; this general picture agreed with what was expected given current models of dwarf galaxies - weaker magnetic fields in the ISM leading to a higher escape of CRe (and resulting reduction in RCNTh emission). This was also backed-up by the relatively low RCNTh fraction - 61 ± 7% at C-band. The observed RC-SFR relation was calibrated to allow the observed RC luminosity of a gas rich dwarf galaxy to be used to infer the SFR; the calibration takes the form SFR [M⊙ yr⁻¹] = 5 x 10⁻¹⁸(RC [WHz⁻¹])0.85. On a resolved basis, only the RCNTh was examined - this is because whether scales of 1 pc, or 1 kpc are investigated, the relationship between the Hα (current SF) and RCTh was not expected to change. Calibrating the resolved RCNTh-SFR relation was best done when using discrete SF regions which varied from 10s up to 100s of pc in size. On these scales, the calibration allows the SFR to be inferred from an observed RCNTh luminosity, and takes the form SFR [M⊙ yr⁻¹] = 1.36 x 10⁻²³(LNTh [WHz⁻¹])1.15. This calibration, however, is only valid for resolved regions forming stars at a rate ≳ 2 x 10⁻⁴M⊙ yr⁻¹. Despite the low flux densities of RCNTh measured from these discrete SF regions, the RCNTh still works well as a SFR tracer whereas Hα, which is largely dependent on stars with mass ≳ 18M⊙, and is thus dependent on the high mass tail of the stellar IMF, will suffer from stochasticity. In a few dwarfs, the equipartition magnetic field strength reaches as high as 30 μG in multiple 100 pc regions, and in one case, 70 μG. However, generally, the weaker magnetic fields in the ISM give the CRe longer lifetimes, and thus more time to be advected out of the galaxy with the magnetic fields frozen into the gas in outflows, or diffuse. This explains in part the lack of RCNTh emission observed in the ISM of dwarf galaxies. Through implementing a simple galactic CRemodel, itwas found that the RCNTh emission associated with the CRe can be used as a SF tracer from approximately 5 up to 70Myr following a burst of SF, while RCTh can be used in its absence prior to 5Myr. The RCNTh luminosity reaches its peak approximately 55Myr after the SF episode, but actually remains nearly constant over the 60Myr following the SF episode, highlighting its potential to be used to infer SFR. The CRemodel also tracked the evolution of the RCNTh spectral index with time. Between values of about -0.4 and -0.7, the RCNTh spectral index can be calibrated to infer the time elapsed since a burst of SF through t[Myr] = -25αNTh. RCNTh spectral indices of -0.8 are consistent with ages between 20 and 55Myr, suggesting that the oft observed spectral index of -0.8 in galaxies may come from the fact that C-band RCNTh emission is dominated by the steep spectral indices of -0.8 from these older SF regions (20-55Myr). For the galaxies that displayed RCNTh emission that was bright enough and sufficiently well resolved, a spectral decomposition of the RC spectrum was performed to infer Hα-independent RCTh, RCNTh, and RCNTh spectral index maps. The spectral decomposition showed DDO50 and NGC1569 to have a low thermal fraction of 23% and 10%, respectively, at C-band, while NGC2366 and NGC4214 were shown to have higher thermal fractions of 48% and 66%, respectively. In summary, dwarf galaxies are not only faint in the RC due to their lower SF activity, but they are also fainter than expected due to CRe escape. Nonetheless, the RC can be used to probe SF in dwarf galaxies not only on a global scale, but also within discrete SF complexes 10s to 100s of pc in size. Theoretically, the RC can be used right from the onset of a burst of SF, where RCTh will dominate, up to ~ 70Myr, at which point RCNTh will dominate. Calibrated by the RC observations in this thesis, both resolved and global SFRs of gas rich, low mass galaxies can be inferred with an uncertainty of ±0.2 dex; the relations allow SFRs of between approximately 2x10⁻⁴ and 0.1M⊙ yr⁻¹ to be inferred.

Recent observations at the James Clerk Maxwell Telescope (JCMT) and elsewhere have identified a class of very deeply embedded, possibly protostellar, sources which are not associated with any of the traditional indicators of star formation, such as HII regions and near-infrared emission, but which do lie close to otherwise isolated H2O masers. This thesis describes a search, based on catalogues of known water maser positions, for new deeply embedded cores similar to those found in S106 and M17. In addition to millimetre molecular line and submillimetre continuum observations, 22 GHz and 8 GHz radio observations have been made of a number of the sources in order to obtain more accurate maser positions and to search for any associated compact HII regions. Observing sources such as these in less active star forming regions provides a cleaner environment in which to examine the maser excitation and the ongoing process of star formation. A sample of 44 water maser sources was observed from which submillimetre continuum emission was detected from 40 (91 per cent). The most striking feature of the data is the close association of the masers with the submillimetre cores: the data are consistent with masers occurring within 6000 AU of the embedded core. The results can be summarised as follows: o High temperature gas has been detected, and most of the submillimetre cores have mean densities greater than 10^6 /cm^3. o The masers have low velocities with respect to the molecular cloud and are uniformly distributed within 6600 AU of the submillimetre core. o The isotropic maser luminosity is proportional to the far-infrared luminosity over more than 5 orders of magnitude. o There is no obvious correlation between the near-infrared spectral class and the maser emission. o Where a radio spectral index is known the majority of sources are optically thin HII regions. The bulk of the remainder are undetected and have a flux density less than 1 mJy. o Masers not associated directly with a submillimetre core show explicit evidence for shocks. Embedded cores \emph{have} been detected with this survey and the maser emission is consistent with collisionally excited pump models.