Now showing items 1-20 of 98

  • Aligned metal absorbers and the ultraviolet background at the end of reionization 

    Doughty, Caitlin; Finlator, Kristian; Oppenheimer, Benjamin D.; Dave, Romeel; Zackrisson, Erik (Oxford University Press, 2018)
    We use observations of spatially-aligned C ii, C iv, Si ii, Si iv, and O i absorbers to probe the slope and intensity of the ultraviolet background (UVB) at z ∼ 6. We accom- plish this by comparing observations with ...
  • Annealing effect of hybrid solar cells based on poly (3-hexylthiophene) and zinc-oxide nanostructures 

    Motaung, David; Malgas, Gerald; Ray, Suprakas S.; Arendse, Christopher (Elsevier, 2013)
    The structural growth and optical and photovoltaic properties of the organic–inorganic hybrid structures of zinc oxide (ZnO)-nanorods/poly-3-hexylthiophene (P3HT) and two variations of organic polymer blends of ZnO/ ...
  • Anti-lensing: the bright side of voids 

    Bolejko, Krzysztof; Clarkson, Chris; Maartens, Roy; Bacon, David; Meures, Nikolai; Beynon, Emma (American Physical Society, 2013)
    More than half of the volume of our Universe is occupied by cosmic voids. The lensing magni ca- tion e ect from those under-dense regions is generally thought to give a small dimming contribution: objects on the far side ...
  • Black hole - galaxy correlations without self-regulation 

    Angles-Alcazar, Daniel; Ozel, Feryal; Dave, Romeel (American Astronomical Society, 2013)
    Recent models of black hole growth in a cosmological context have forwarded a paradigm in which the growth is self-regulated by feedback from the black hole itself. Here we use cosmological zoom simulations of galaxy formation ...
  • Bringing together knowledge and capabilities: a case study of engineering graduates 

    Case, Jennifer M.; Marshall, Delia (Springer Verlag, 2016)
    In contemporary times there is a renewed focus on the purposes of university education in science or engineering, especially inemerging economycontexts like South Africa where the massification of higher education is in ...
  • Calibrating photometric redshifts with intensity mapping observations 

    Alonso, David; Ferreira, Pedro G.; Jarvis, Matt; Moodley, Kavilan (American Physical Society, 2017)
    Imaging surveys of galaxies will have a high number density and angular resolution yet a poor redshift precision. Intensity maps of neutral hydrogen (HI) will have accurate redshift resolution yet will not resolve ...
  • Characterization of silicon nitride thin films deposited by hot-wire CVD at low gas flow rates 

    Oliphant, Clive J.; Arendse, Christopher; Muller, Theophillus F.G.; Knoesen, Dirk (Elsevier, 2013)
    We examined the chemical, structural, mechanical and optical properties of amorphous hydrogenatedsilicon nitride thin films deposited by hot-wire chemical vapour deposition using SiH4, NH3and H2gases at total flow rates ...
  • Clustering of quintessence on horizon scales and its imprint on HI intensity mapping 

    Duniya, Didam G.A.; Bertacca, Daniele; Maartens, Roy (IOP Science, 2013)
    Quintessence can cluster only on horizon scales. What is the effect on the observed matter distribution? To answer this, we need a relativistic approach that goes beyond the standard Newtonian calculation and deals properly ...
  • Comparative study: the effect of annealing conditions on the properties of P3HT:PCBM blends 

    Motaung, David E.; Malgas, Gerald; Nkosi, Steven S.; Mhlongo, Gugu H.; Mwakikunga, Bonex W.; Malwela, Thomas; Arendse, Christopher; Muller, Theophillus F. G.; Cummings, Franscious R. (Springer Verlag, 2013)
    This paper presents a detailed study on the role of various annealing treatments on organic poly(3-hexylthiophene) and [6]-phenyl-C61-butyric acid methyl ester blends under different experimental conditions. A combination ...
  • A comparison of Einstein-Boltzmann solvers for testing General Relativity 

    Bellini, Emilio; Barreira, A.; Frusciante, N.; Ballardini, M. (American Physical Society, 2018)
    We compare Einstein-Boltzmann solvers that include modifications to General Relativity and find that, for a wide range of models and parameters, they agree to a high level of precision. We look at three general purpose codes ...
  • Comparison of Hi and optical redshifts of galaxies - The impact of redshift uncertainties on spectral line stacking 

    Maddox, Natasha; Hess, Kelley M.; Blyth, S.-L.; Jarvis, Matt (Oxford University Press, 2013)
    Accurate optical redshifts will be critical for spectral co-adding techniques used to extract detections from below the noise level in ongoing and upcoming surveys for Hi, which will extend our current understanding of ...
  • The complex physics of dusty star-forming galaxies at high redshifts as revealed by Herschel and Spitzer 

    Lo Faro, Barbara; Franceschini, Alberto; Vaccari, M.; Silva, L.; Rodighiero, G.; Berta, S.; Bock, J.; Burgarella, D.; Buat, V.; Cava, A.; Clements, D.L.; Cooray, Asantha; Farrah, D.; Feltre, Anna; Gonzalez-Solares, Eduardo A.; Hurley, P.; Lutz, D.; Magdis, G.; Magnelli, B.; Marchetti, L.; Oliver, S.J.; Page, Matthew J.; Popesso, P.; Pozzi, F.; Rigopoulou, D.; Rowan-Robinson, M.; Roseboom, I.G.; Scott, Douglas; Smith, A.J.; Symeonidis, M.; Wang, L.; Wuyts, S. (IOP Publishing, 2013)
    We combine far-infrared photometry from Herschel (PEP/HerMES) with deep mid-infrared spectroscopy from Spitzer to investigate the nature and the mass assembly history of a sample of 31 luminous and ultraluminous infrared ...
  • Constraining the bright-end of the UV luminosity function for z ~ 7-9 galaxies: results from CANDELS/GOODS-South 

    Lorenzoni, Silvio; Bunker, Andrew J.; Wilkins, Stephen M.; Caruana, Joseph; Stanway, Elizabeth R.; Jarvis, Matt (OUP, 2013)
    The recent Hubble Space Telescope near-infrared imaging with the Wide-Field Camera #3 (WFC3) of the GOODS-South field in the CANDELS program covering nearly 100 arcmin2, along with already existing Advanced Camera for ...
  • Constraints on anisotropic cosmic expansion from supernovae 

    Kalus, Benedict; Schwarz, Dominik J.; Seikel, Marina; Wiegand, Alexander (Edp Sciences, 2013)
    AIMS. We test the isotropy of the expansion of the Universe by estimating the hemispherical anisotropy of supernova type Ia (SN Ia) Hubble diagrams at low redshifts (z < 0.2). METHODS. We compare the best fit Hubble ...
  • The COS-Halos survey: Rationale, design and a census of circumgalactic neutral hydrogen 

    Tumlinson, Jason; Thom, Christopher; Dave, Romeel; Werk, Jessica K.; Prochaska, J. Xavier; Tripp, Todd M.; Katz, Neal; Oppenheimer, Benjamin D.; Meiring, Joseph D.; Ford, Amanda Brady; O'Meara, John M.; Peeples, Molly S.; Sembach, Kenneth R.; Weinberg, David H. (IOP Publishing, 2013)
    We present the design and methods of the COS-Halos survey, a systematic investigation of the gaseous halos of 44 z = 0.15–0.35 galaxies using background QSOs observed with the Cosmic Origins Spectrograph aboard the Hubble ...
  • The cosmic evolution of the IMF under the Jeans conjecture with implications for massive galaxies 

    Narayanan, Desika; Dave, Romeel (Oxford University Press, 2013)
    We examine the cosmic evolution of a stellar initial mass function (IMF) in galaxies that varies with the Jeans mass in the interstellar medium, paying particular attention to the K-band stellar mass-to-light ratio (M/LK) ...
  • Cosmology on ultralarge scales with intensity mapping of the neutral hydrogen 21 cm emission: limits on primodial non-gaussianity 

    Camera, Stefano; Santos, Mario G.; Ferreira, Pedro G.; Ferramacho, Luis (American Physical Society, 2013)
    The large-scale structure of the Universe supplies crucial information about the physical processes at play at early times. Unresolved maps of the intensity of 21 cm emission from neutral hydrogen HI at redshifts z ~ 1 − ...
  • Cosmology with photometrically classified type IA supernovae from the SDSS-II supernova survey 

    Campbell, Heather; D’Andrea, Chris B.; Nichol, Robert C.; Sako, Masao; Smith, Mathew (The American Astronomical Society, 2013)
    We present the cosmological analysis of 752 photometrically–classified Type Ia Supernovae (SNe Ia) obtained from the full Sloan Digital Sky Survey II (SDSS-II) Supernova (SN) Survey, supplemented with host–galaxy ...
  • A deep search for faint galaxies associated with very low-redshift C iv absorbers: A case with cold-accretion characteristics 

    Burchett, Joseph N.; Tripp, Todd M.; Werk, Jessica K.; Howk, J. Christopher; Dave, Romeel; Prochaska, J. Xavier; Ford, Amanda Brady (The American Astronomical Society, 2013)
    Studies of QSO absorber–galaxy connections are often hindered by inadequate information on whether faint/dwarf galaxies are located near the QSO sight lines. To investigate the contribution of faint galaxies to QSO ...
  • EC 10246-2707: a new eclipsing sdB + M dwarf binary⋆ 

    Barlow, B.N.; Kilkenny, David; Drechsel, H.; Dunlap, B.H. (OUP, 2013)
    We announce the discovery of a new eclipsing hot subdwarf B + M dwarf binary, EC 10246-2707, and present multi-colour photometric and spectroscopic observations of this system. Similar to other HW Vir-type binaries, the ...