Using data from the SCUBA Legacy Catalogue (850 µm) and Spitzer (3.6 - 70 µm), we explore dense cores in the Ophiuchus, Taurus, Perseus, Serpens, and Orion molecular clouds. In particular, we focus on identifying which cores host young stars while others remain starless. Understanding the nature of star formation and the influence of local environment will give us insight into several key properties, such as the origin of stellar mass. Here, we present starless and protostellar core mass functions (CMFs) for the five clouds. We develop a new method to discriminate starless from protostellar cores, using Spitzer colours and positions. We found best-fit slopes to the high-mass end of −1.26±0.20, −1.22±0.06, −0.95±0.20, and −1.85±0.53 for Ophiuchus, Taurus, Perseus, and Orion, respectively. We were unable to fit a slope to our fifth cloud, Serpens. Broadly, these slopes are consistent with the −1.35 power-law seen in the Salpeter IMF, but suggest some differences. We examined a variety of trends between these CMF shapes and their parent cloud properties, potentially finding a correlation between the high-mass slope and temperature. We also attempt to predict what future surveys with SCUBA-2 will detect in each of our clouds.

Magnetization dynamics in polycrystalline Permalloy thin films were studied in-situ using a time-resolved magneto-optic Kerr effect microscope (TR-MOKE). The films, in thicknesses from 9 to 22 nm, were thermally evaporated in a high-vacuum (<10⁻⁸ mbar) environment. Two important dynamic parameters of the magnetization, the precessional frequency and effective damping constant α eff, are obtained from the picosecond time-resolved evolution of the magnetization after a magnetic field pulse excitation. For all film thicknesses investigated, the magnetization carried out precessional motion at a frequency of ~2 GHz. The effective damping constant α eff is extracted from the precessional decay time τ. The decay time is obtained by fitting the experimental time trace of the magnetization to a damped sine function of the form M(t)=Mo e -t/τ sin(ωt-φ), where ω is the angular frequency of the precession mode and φ is the initial phase of the precession. For the thinnest film investigated, α eff reaches the value of 0.32, considerably higher than any previously reported values. The physical origin of the increased magnetic damping is discussed in terms of the surface roughness induced extrinsic damping in magnetic thin films, but the experimentally found thickness-dependence of α eff, however, does not agree with the prediction. The discrepancy is attributed to the percolation of Permalloy islands into connected clusters occurring at the thickness of ~18 nm.

DLAs are the primary reservoirs of neutral gas available for star formation at high redshift. However, DLAs are metal poor and lack molecular gas. In this thesis, I present a study of an extraordinary case of a z=2.06 sub-DLA towards the quasar J2123−0050, which is characterized by a metallicity that approaches solar, and a high H2 molecular fraction (log f(H2) = −2.54). Furthermore, this SDLA harbors HD molecules, only the third such detection at high redshift, and with the highest (HD/2H2) fraction of -2.75. To understand these observations, I study the effects of dust depletion and photoionization on the interpretation of raw abundance measurements. I find that the magnitude of photoionization and dust depletion effects has a profound impact on the interpretation of this SDLA. The calculated corrections lower the elemental and molecular abundances suggesting that the ISM in the SDLA towards J2123−0050 exhibits properties similar to the gas in the local sightlines.

Initial results are presented for two analyses using data from the recently completed laser calibration system of the time projection chambers for the Tokai-to- Kamioka long baseline neutrino oscillation experiment. Data taken with the first two production time projection chambers, while tested at TRIUMF, has been used to investigate the signal arrival time and subsequently the ionization drift speed and the relative gain of the micromegas and electronics systems. It has been found that an analytic Gaussian t produces the best overall results for establishing an arrival time, having both the lowest standard deviation, of 11 ns, and good amplitude dependence while remaining fast. Using the analytic fit technique the drift speeds of ionization has been found to be in agreement with the expected values at the 2% level. The largest of the contributing errors were found to be due to systematics involved in the calculation of the ionization production time and will be reduced in future. Relative gain analysis results have shown that the gain can be calculated based on a simple model relating the mean signal size of data channels to the variance. Further gain results have shown that an offset found in the laser data can be corrected for by sampling signal amplitudes from channels that do not detect ionization or can remain uncorrected if the fitting for the relative gain includes a correction parameter. Preliminary results of the gain's dependence on the gas temperature and pressure have shown a positive nonzero slope. However, systematic errors were found be large relative to the temperature and pressure ranges. This dependence and its use as a correction for such changes will need to be investigated further at the experiment site in Japan.

Although the Sloan Digital Sky Survey (SDSS) has compiled an unprecedented amount of photometric data on stellar populations in the Milky Way, it is not presently possible to accurately and consistently interpret these data due to the lack of precise fiducial stellar sequences and color-temperature relations for the new 'u'g'r'i'z' photo-metric system. In order to address these deficiencies, this study describes an extensive observational project that has obtained high-quality and homogeneous photometry for a number of different Galactic star clusters spanning a wide range in meta.llicity (-2.5 ≤ [Fe/H] ≤ +0.3), as observed in the u'g'r'i'z' passbands with the MegaCam wide-field imager on the Canada-France-Hawaii Telescope. By employing these purest of stellar populations, fiducial sequences have been defined from color-magnitude diagrams (CMDs) that. extend from the tip of the RGB down to approximately 4 magnitudes below the turnoff points: these have been accurately calibrated to the standard u'g'r'i'z` system via a set of secondary photometric standards located within these same clusters. Consequently, they can serve as a valuable set of empirical fiducials for the interpretation of stellar populations data in the system, as well as calibrators for the transformation of stellar isochrones to the u'g'r'i'z' bandpasses. In fact. when a new grid of theoretical color-Teff relations and bolometric corrections for the system is computed from Kurucz model atmospheres and employed to translate isochrones to the observed planes, generally very good and consistent fits to the CMDs of the metal-poor ([Fe/H] <0.0) globular clusters M 92, M 13, and M 71 are found, once reasonable estimates of the cluster parameters are assumed (the only obvious discrepancy is a shift of ~ 0.01 - 0.03 mag between the predicted and observed giant branches when the models are fitted to the main sequences). More-over, the same isochrone fits are entirely consistent with those inferred from cluster observations in other photometric systems - notably, the BV(RI) , and uvby systems. At the metal-rich end ([Fe/H] ≥ 0.0), however. these transformations fail to match the observed loci of cool, main-sequence stars (Teff ≤ 5000K) in the open clusters M 67 and NGC 6791. An exploration into possible causes of these discrepancies is provided.

No description available.

Electrochemical and spectroelectrochemical data was obtained for a silver electrode modified with oxazine 720. A quasi-reversible redox behaviour was observed for the modified electrode. Surface adsorption density, calculated from the measured electrochemical charge transfer, is higher than would be expected for a monolayer of flat-adsorbed ox¬azine 720. Surface-enhanced Raman scattering (SERS) data, in conjunction with results of a density functional theory (DFT) calculation, suggest that the molecule is adsorbed with its rings perpendicular to the electrode surface, consistent with the electrochemically estimated adsorption density. SERS was recorded in situ at different applied potentials. The SERS intensity remains relatively stable between -200 and -500 mV (versus AglAgCl Cl-sat), but decreases dramatically as the applied potential is made more negative than -500 mV. Ths is consistent with the onset of oxazine 720 reduction observed during cyclic voltammetry. The spectroelectrochemical data indicates that oxazine 720 remains adsorbed at the SERS-active sites even in its reduced form. Similar in situ SERS data was collected for rhodamine 6G and pyridine. Spectra in the Stokes and anti-Stokes regions were obtained at several applied potentials using two different laser excitation energies. Normalized ratios of the anti-Stokes to Stokes intensities were calculated for various vibrational bands of the three molecules. The measured ratios vary with changes in the excitation energy, the applied voltage and the energy of the vibrational mode being investigated. The ratios for oxazine 720 show a preferential enhancement of the Stokes scattering while the ratios for rhodamine 6G indicate an enhancement of the anti-Stokes scattering. For pyridine, the preferential enhancement changes between Stokes and anti-Stokes depending on the excitation wavelength used, the applied voltage and the vibrational band being examined. The main trends of the anti-Stokes to Stokes ratios can be satisfactorily explained using resonance models based on standard SERS theories. No evidence of a SERS-induced non-thermal population distribution among the vibrational states of the adsorbed molecules (vibrational optical pumping) was observed.

We generate a suite of idealized two-body X-ray cluster merger simulations with which we study the impact of mergers on the properties of relaxed X-ray clusters. We identify a common dynamical progression which typical merger events proceed through and use simulated Chandra observations to identify observable transient structures in surface brightness, temperature and entropy which emerge in the process. These simulated observations are also used to determine when the systems would appear relaxed under reasonable observational circumstances. This time is compared to other, more quantitative measures of a system's apparent dynamical state, all of which are compared to the time when the system formally relaxes to a virialized or hydrostatic state. The effects of mergers on observable X-ray and Sunyaev-Zel'dovich (SZ) observables are then explored and the contribution of merger events on scaling relations generated from these quantities examined. We conclude that mergers are likely not capable of accounting for the observed scatter in these relations. We then examine the effects of mergers on the morphology and structure of compact cool cores (CCCs) observed to be present in the majority of X-ray clusters. We find that mergers can warm CCC systems, potentially transforming them (either transiently or for extended periods) into two additional morphologies: extended warm core (EWC) and compact warm core (CWC) systems. These morphologies segregate in all scaling relation planes in a way which is qualitatively consistent with what is observed. Lastly, we find that mergers do not efficiently mix the intracluster medium (ICM). Mergers between systems which initially possess central metalicity gradients (as CCC systems generally do) produce remnants with metalicity gradients very similar to those of the parent systems. Together. these results pose a. significant challenge to a popular hypothesis in X-ray cluster studies: that mergers are responsible for producing extended core systems.

No description available.

Galaxies grow and evolve via the repeated process of hierarchical merging, with smaller galaxies being cannibalized by larger and correspondingly brighter ones. Thus in galaxy clusters it is the brightest cluster galaxy (BCG) that lies at the top of the galaxian food chain and deep within the cluster potential the BCG grows to become one of the most massive galaxies in the universe. Baryonic feedback processes associated with the formation of the BCG (eg., AGN, star formation, stellar winds and chemical enrichment) affect the balance between heating and cooling of the intra-cluster medium (ICM) which in turn, through replenishment of the cold gas reservoir of the BCG, feeds back on these processes. This interconnection between the BCG and the state of the cluster gas has direct implications for theories of both galaxy and cluster evolution. Thanks to recent advances in observational techniques it has become possible to study the link between BCG and host cluster properties across a wide range of multi-wavelength information. Using deep imaging data taken with the Canada-France-Hawaii Telescope as part of the Canadian Cluster Comparison Project. (CCCP). we examine the surface brightness distributions in g' and r' of 28 BCGs in a redshift range 0.15 z 0.55 residing in massive clusters with Tx > 5 and compare them to the global X-ray properties of their hosts. We fit R1/4 models to the surface brightness profiles and find that the Kormendy relation of BCGs, when corrected for passive evolution. is consistent with that of the local elliptical population. We identify a subset of BCGs with extraordinarily blue centers (0.1 < dlog(g' - r')/dlog(r) < 1.3 within 15 h70-1 kpc) extending several times the fwhm of the psf. These objects all lie on the most luminous side of the scatter in the Lx-Tx relation for a given T1, an effect which previous authors have shown can be explained by cooling of the ICM (McCarthy et al. 2004). We find independent evidence from previous studies that these systems are all hosts of recent star formation. The blue cores in these BCGs cause them to be displaced from the red sequences of their host clusters; in the most extreme cases this displacement is 11-nag. These findings are contradictory to the current paradigm of elliptical galaxy formation within clusters where star formation is thought to have a negligible effect in the most massive cluster ellipticals at late cosmic times. Furthermore BCG total magnitude is found to correlate with host cluster deviation from the mean Lx-Tx relation. We argue that cooling and pre-heating of the Intra-Cluster-Medium has an important affect on the global and structural properties of the stellar component of BCGs. Not all BCGs are red and dead, there is a need to incorporate an external source of cold gas replenishment into quenching models of galaxy formation in clusters in order to reconcile these observations.