We report exploratory Chandra observations of the ultraluminous quasar SDSS J010013.02+280225.8 at redshift 6.30. The quasar is clearly detected by Chandra with a possible component of extended emission. The rest-frame 2-10 keV luminosity is 9.0(+4.5)(+9.1) x 10(45) erg s(-1) with an inferred photon index of G = 3.03(-0.70)(+0.78). This quasar is X-ray bright, with an inferred X-ray-to-optical flux ratio alpha(ox) = -1.22(-0.05)(+0.07), higher than the values found in other quasars of comparable ultraviolet luminosity. The properties inferred from this exploratory observation indicate that this ultraluminous quasar might be growing with super-Eddington accretion and probably viewed with a small inclination angle. Deep X-ray observations will help to probe the plausible extended emission and better constrain the spectral features for this ultraluminous quasar.

There have been many changes in Geographical Information Systems (GIS) technology which are beneficial for analysis and visualisation of Geographical Information (GI) but these have failed to be applied to non GIS users. The development of a computer based working environment for using GI within generic decision-making situations is a necessity if more use is to be made of GI by non GIS specialists. Problems are outlined for the incorporation of GI into existing systems : GIS and Spatial Decision Support Systems (SDSS). Issues of usability, integration of software/information and functionality have slowed the wider acceptance of GIS. 'These issues have lead to the development of a conceptual functional model of a Geographical Operating Environment (GOE). The GOE is proposed as a solution to the use of GI within a generic computer based decision-making environment for non GIS users. The GOE integrates the use of GI and non GI to allow the user to view and analyse information within a decision-making context. A series of prototypes have been developed and tested, mostly in conjunction with commercial organisations. The research has shown that there is much benefit in facilitating access to GI and non GI by decision-makers and that alternate strategies can be visualised and analysed. However, there are still problems for the mainstream use of GI within generic decision-making using existing computer systems from both a technological and sociological perspective. Decision-makers would benefit from the .additional analytical and visualisation techniques that can be applied to GI through the use of a GI based working environment such as the GOE.

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Neighborhoods are organic entities that are in a state of constant change and are driven by the specific context of the problem being investigated. The subsequent lack of consensus on a universal geographic definition for what constitutes a neighborhood can lead to biased interpretations of relationships between human activities and place. Further, while existing geographical information system software allows users to combine a range of geographic objects to generate regional units of analyses, their design does not explicitly assess how changing patterns, such as populations, impact the data expressed within them. This research develops an exploratory geographical information system framework that allows users to dynamically delineate neighborhoods based on user-specified characteristics. These include socioeconomic and similar measurements of neighborhood classification from information obtained from secondary data sources, including parcel data, land use/land cover information, and attribute data provided by the United States Postal Service. The proposed methodology creates custom geographies from readily available tract data obtained from various federal and state data repositories to produce indices. By allowing the user to dynamically weigh the combinations of variables used to define their neighborhood, this thesis introduces a solution to a common analytical problem in the discipline.

Interactions between pairs of isolated dwarf galaxies provide a critical window into low-mass hierarchical, gas-dominated galaxy assembly and the build-up of stellar mass in low-metallicity systems. We present the first Very Large Telescope/Multi Unit Spectroscopic Explorer (VLT/MUSE) optical integral field unit (IFU) observations of the interacting dwarf pair dm1647+21 selected from the TiNy Titans survey. The Ha emission is widespread and corresponds to a total unobscured star formation rate (SFR) of 0.44 M-circle dot yr(-1), which is 2.7 times higher than the SFR inferred from Sloan Digital Sky Survey (SDSS) data. The implied specific SFR (sSFR) for the system is elevated by more than an order of magnitude above non-interacting dwarfs in the same mass range. This increase is dominated by the lower-mass galaxy, which has a sSFR enhancement of > 50. Examining the spatially resolved maps of classic optical line diagnostics, we find that the interstellar medium (ISM) excitation can be fully explained by star formation. The velocity field of the ionized gas is not consistent with simple rotation. Dynamical simulations indicate that the irregular velocity field and the stellar structure is consistent with the identification of this system as an ongoing interaction between two dwarf galaxies. The widespread, clumpy enhancements in the star formation in this system point to important differences in the effect of mergers on dwarf galaxies, compared to massive galaxies; rather than the funneling of gas to the nucleus and giving rise to a nuclear starburst, starbursts in low-mass galaxy mergers may be triggered by large-scale ISM compression, and thus may be more distributed.

Issus de l'effondrement gravitationnel des fluctuations de matière primordiales, les amas de galaxies sont constitués d'un halo de matière noire, d'un plasma de baryon ou « gaz chaud » et de galaxies. Le comptage des amas apporte des contraintes fortes sur la cosmologie.Mon travail consiste à améliorer la détection de la composante de gaz chaud des amas, à la fois pour des structures proches et lointaines. Ce gaz chaud est détectable dans les cartes du satellite Planck par effet Sunyaev-Zel'dovich et dans les cartes du satellite ROSAT par rayonnement de freinage.La première partie de cette thèse consiste à détecter du gaz chaud dans les cartes de Planck à la position des quasars de l'expérience BOSS, donc dans des structures lointaines.Le signal est dominé par une émission de type poussière. J'ai donc élaboré un filtre capable d'extraire un signal de gaz chaud sous-dominant et de le séparer de l'émission de poussière. Le signal de gaz chaud obtenu par cette approche est significatif pour les structures à redshift z >2.5.La seconde partie de cette thèse, la détection simultanée, est dédiée à la construction d'un filtre capable d'extraire des amas (à z<1.5) individuellement dans les données ROSAT et adapté à la statistique du bruit. Ce filtre est en outre conçu dans la perspective d'être combiné avec le filtre utilisé pour détecter les amas dans les données Planck. L'objectif final étant d'obtenir plus d'amas moins massifs. / Originating from the gravitational collapse of the primordial fluctuations of matter, galaxy clusters are the mixture of a dark matter halo, a baryonic plasma also called « hot gas » and several galaxies. Cluster counts provide stringent constraints on cosmology.Improving the detection of the hot gas component in nearby or distant structures is the main goal of my work. We can detect this hot gas in the Planck satellite maps thanks to the Sunyaev-Zel'dovich effect and in the ROSAT satellite maps by bremsstrahlung.The first part of my thesis is dedicated to the detection of hot gas in Planck maps at the positions of BOSS quasars, so in distant structures.Dust-like emission dominates our signal. I developped a new filter in order to separate the possible sub-dominant hot gas emision from the dust one. I get a significnt hot gas signal for structures with redshift z >2.5.In the second part of the thesis, the simultaneous detection, I build a filter suited for extracting clusters (z<1.5) individually in the ROSAT data respecting the noise statitistics. This filter is also designed to be combined with the filter used for detecting clusters in Planck maps. Increasing the number of less massive clusters will be the final goal.

The growing necessity for meaningful climate change response has encouraged the development of global warming mitigation and adaptation initiatives. Urban solar energy generation is one opportunity that has been investigated by numerous cities through various solar potential Web-applications. However, as solar feasibility can vary considerably across a small geographic area due to variations in local topography and feature shading, there is no one-size-fits-all solution to be implemented. This thesis investigates how a Web-based spatial decision support system (SDSS) can enable non-experts to explore urban solar feasibility and, to a lesser extent, issues related to urban heat. First, a conceptual framework is developed that investigates the linkages between SDSS, Web technologies, public participation, volunteered geographic information, and existing green energy initiatives. This framework identifies the relevance between these fields of study as well as a number of opportunities for improving on past work and taking advantage of new technical capabilities. Second, in order to test the opportunities identified, SunSpot was developed. This Web-SDSS investigates rooftop solar feasibility as well as land cover and surface temperature dynamics relating to the urban heat-island effect in Toronto, Ontario, Canada. A number of solar resource datasets were developed in order to facilitate the decision making capabilities of SunSpot. This was done using a combination of different topographical data sources, atmospheric data, and a raster-based irradiance model called Solar Analyst. Third, a number of in-person workshops were conducted to obtain feedback on SunSpot’s usability and ability for users to understand the visual layers and results. Finally, this feedback was analyzed to identify the successes and challenges of SunSpot’s capabilities and design. This revealed a number of recommendations for further development of SunSpot, as well as opportunities for future research relating to the development of local scale solar resource data and the development of similar Web-SDSS applications.

Studying how SN Ia rates (SNR) correlate with host galaxy properties is an important step in understanding the exact nature of SN Ia. Taking a sample of SNe and galaxies from the SDSS, we obtain the optimum parameter values for the A+B model for SNR, which states that SNR scale linearly with mass and star formation rate of the host, and compare them with previous work. We then proceed to show that the A+B model deviates very significantly from the SNR behaviour in our sample, demonstrate that no reasonable values for A and B could possibly match the observations, and investigate the possibility of a third-parameter correction to the generic A+B model. We find that several hypothesised models seem to match the distribution of SNRs in our sample; however, discriminating between them is a difficult task. We interpret the above to be an indicator that a new parameter may need to be taken into account when modelling SNR, and we present metallicity as a possible candidate for the new parameter. Also, by investigating decomposed bulge + disk components of the host galaxies, we find that the spatial positions of SNe Ia are correlated with bulge luminosity, but not with galaxy total luminosity or disk luminosity. It is also shown that SNe do not preferentially occur in bulge-dominated galaxies. Our interpretation of these results is that SNe arise from a population having a spatial distribution which correlates very well with bulge luminosity, but does not usually contribute to bulge luminosity. / Graduate

The growing necessity for meaningful climate change response has encouraged the development of global warming mitigation and adaptation initiatives. Urban solar energy generation is one opportunity that has been investigated by numerous cities through various solar potential Web-applications. However, as solar feasibility can vary considerably across a small geographic area due to variations in local topography and feature shading, there is no one-size-fits-all solution to be implemented. This thesis investigates how a Web-based spatial decision support system (SDSS) can enable non-experts to explore urban solar feasibility and, to a lesser extent, issues related to urban heat. First, a conceptual framework is developed that investigates the linkages between SDSS, Web technologies, public participation, volunteered geographic information, and existing green energy initiatives. This framework identifies the relevance between these fields of study as well as a number of opportunities for improving on past work and taking advantage of new technical capabilities. Second, in order to test the opportunities identified, SunSpot was developed. This Web-SDSS investigates rooftop solar feasibility as well as land cover and surface temperature dynamics relating to the urban heat-island effect in Toronto, Ontario, Canada. A number of solar resource datasets were developed in order to facilitate the decision making capabilities of SunSpot. This was done using a combination of different topographical data sources, atmospheric data, and a raster-based irradiance model called Solar Analyst. Third, a number of in-person workshops were conducted to obtain feedback on SunSpot’s usability and ability for users to understand the visual layers and results. Finally, this feedback was analyzed to identify the successes and challenges of SunSpot’s capabilities and design. This revealed a number of recommendations for further development of SunSpot, as well as opportunities for future research relating to the development of local scale solar resource data and the development of similar Web-SDSS applications.

A brief Chandra observation of the ultraluminous quasar SDSS J010013.02+280225.8 at redshift 6.326 showed it to be a relatively bright, soft X-ray source with a count rate of about 1 count ks(-1). In this article, we present results for the quasar from a 65-ks XMM-Newton observation, which constrains its spectral shape well. The quasar is clearly detected with a total of similar to 460 net counts in the 0.2-10 keV band. The spectrum is characterized by a simple power-law model with a photon index of Gamma = 2.30(-0.10)(+0.10) and the intrinsic 2-10 keV luminosity is 3.14 x 10(45) erg s(-1). The 1 sigma upper limit to any intrinsic absorption column density is N-H = 6.07 x 10(22) cm(-2). No significant iron emission lines were detected. We derive an X-ray-to- optical flux ratio alpha(ox) of -1.74 +/- 0.01, consistent with the values found in other quasars of comparable ultraviolet luminosity. We did not detect significant flux variations either in the XMM-Newton exposure or between XMM-Newton and Chandra observations, which are separated by similar to 8 months. The X-ray observation enables the bolometric luminosity to be calculated after modelling the spectral energy distribution: the accretion rate is found to be sub-Eddington.