Physics and Astronomy: Recent submissions

Now showing items 421-440 of 533

    • Foreground contamination in Lyα intensity mapping during the epoch of reoinization 

      Santos, Mario, G.; Gong, Yan (IOP Science, 2014)
      The intensity mapping of Lyα emission during the epoch of reionization will be contaminated by foreground emission lines from lower redshifts. We calculate the mean intensity and the power spectrum of Lyα emission at z ...

    • Pulsations and eclipse-time analysis of HWVir 

      Baran, A. S.; Østensen, R. H.; Telting, J. H.; Vos, J.; Kilkenny, D.; Vuckovic, M.; Reed, M. D.; Silvotti, R.; Jeffery, C. S.; Parsons, S. G.; V. S. Dhillon, V. S.; Marsh, T. R. (Oxford University Press, 2018)
      We analysed recent K2 data of the short-period eclipsing binary systemHWVir,which consists of a hot subdwarf-B type primary with an M-dwarf companion.We determined the mid-times of eclipses, calculated O–C diagrams, and ...

    • Radon-222 measurements at Cape Point: A characterization of a 15-year time series 

      Botha, R.; Labuschagne, C.; Williams, A.G.; Bosman, G.; Brunke, E.-G.; Rossouw, A.; Lindsay, R. (National Association for Clean Air, 2018)
      The Cape Point (CPT) Global Atmosphere Watch (GAW) research station have been monitoring climatically significant trace gases for four decades. Among these is radon, a naturally occurring noble gas with a large continental ...

    • Investigation of excited 0+ states in 160Er populated via the (p, t) two-neutron transfer reaction 

      Burbadge, C.; Triambak, S.; Wirth, H.-F. (EDP Sciences, 2018)
      Many efforts have been made in nuclear structure physics to interpret the nature of low-lying excited 0+ states in well-deformed rare-earth nuclei. However, one of the difficulties in resolving the nature of these states ...

    • Diurnal variations in global Joule heating morphology and magnitude due to neutral winds. 

      Kosch, Mike; Billett, D. D.; Grocott, A.; Wild, J. A.; Walach, M.-T. (Wiley, 2018)
      In the polar ionosphere, variations in Joule heating are significantly controlled by changes in plasma convection, such as that brought about by changes in the interplanetary magnetic field. However, another important ...

    • Calibrating the James Webb Space telescope filters as star formation rate indicators 

      Senarath, Madhooshi R.; Brown, Michael J. I.; Cluver, Michelle E.; Moustakas, John; Armus, Lee; Jarrett, Thomas H. (American Astronomical Society, 2018)
      We have calibrated the 6.5m James Webb Space Telescope (JWST) mid-infrared (MIR) filters as star formation rate (SFR) indicators, using JWST photometry synthesized from Spitzer spectra of 49 low-redshift galaxies, which ...

    • nIFTy galaxy cluster simulations – V. Investigation of the cluster infall region 

      Arthur, Jake; Pearce, Frazer R.; Gray, Meghan E.; Elahi, Pascal J.; Knebe, Alexander; Beck, Alexander M.; Cui, Weiguang; Cunnama, Daniel; Dave, Romeel (Oxford University Press, 2016)
      We examine the properties of the galaxies and dark matter haloes residing in the cluster infall region surrounding the simulated cold dark matter galaxy cluster studied by Elahi et al. at z = 0. The 1.1 × 1015 h−1M ...

    • First ground-based observations of sprites over southern Africa 

      Nnadih, Stanislaus; Kosch, Mike; Martinez, Peter; Bor, Jozsef (Academy of Science of South Africa, 2018)
      Sprites are the optical signatures of electrical discharges in the mesosphere triggered by large lightning strikes associated with thunderstorms. Since their discovery in the late 1980s, sprites have been observed ...

    • The observed galaxy bispectrum from single-field inflation in the squeezed limit 

      Koyama, Kazuya; Umeh, Obinna; Maartens, Roy; Bertacca, Daniele (IOP Publishing, 2018)
      Using the consistency relation in Fourier space, we derive the observed galaxy bispectrum from single- eld in ation in the squeezed limit, in which one of the three modes has a wavelength much longer than the other two. ...

    • The Galactic halo pulsar population 

      Rajwade, Kaustubh; Chennamangalam, Jayanth; Lorimer, Duncan R.; Karastergiou, Aris (Oxford University Press, 2018)
      Most population studies of pulsars have hitherto focused on the disc of the Galaxy, the Galactic centre, globular clusters, and nearby galaxies. It is expected that pulsars, by virtue of their natal kicks, are also to ...

    • Predicting the neutral hydrogen content of galaxies from optical data using machine learning 

      Rafieferantsoa, Mika; Andrianomena, Sambatra; Dave, Romeel (Oxford University Press, 2018)
      We develop a machine learning-based framework to predict the Hi content of galaxies using more straightforwardly observable quantities such as optical photometry and environmental parameters. We train the algorithm on z ...

    • Synergies between intensity maps of hydrogen lines 

      Fonseca, Jose; Maartens, Roy; Santos, Mario G. (Oxford University Press, 2018)
      We study synergies between Hi 21cm and Hα intensity map observations, focusing on SKA1- like and SPHEREx-like surveys. We forecast how well such a combination can measure features in the angular power spectrum on the ...

    • 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 ...

    • News from the EREBOS project 

      Schaffenroth, Veronika; Barlow, Brad; Geier, Stephan; Vučković, Maja; Kilkenny, Dave; Schaffenroth, Johannes (De Gruyter Open, 2017)
      Planets and brown dwarfs in close orbits will interact with their host stars, as soon as the stars evolve to become red giants. However, the outcome of those interactions is still unclear. Recently, several brown dwarfs ...

    • Forming the Moon from terrestrial silicate-rich material 

      de Meijer, R.J.; Anisichkin, V.F.; van Westrenen, W. (Elsevier, 2013)
      Recent high-precision measurements of the isotopic composition of lunar rocks demonstrate that the bulk silicate Earth and the Moon show an unexpectedly high degree of similarity. This is inconsistent with one of the ...

    • Visible and IR photoluminescence of c-FeSi@a–Si core–shell nano-fibres produced by vapour transport 

      Thabethe, Sibongiseni; Linganiso, Ella; Motaung, David; Mashapa, Matete G.; Nkosi, Steven; Arendse, Christopher; Mwakikung, Bonex W. (Elsevier, 2013)
      The procedures for the synthesis of amorphous ε-FeSi/Sicore–shell nanofibres by vapour transport in a CVD configuration are reported. Crystallite studies by the Williamson-Hall method show the sizes to be typically about ...

    • 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 ...

    • 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 ...

    • Octupole correlations in the structure of O2 bands in the N=88 nuclei150Sm Gd 

      Bvumbi, S.P.; Sharpey-Schafer, J.F.; Jones, P.M.; Mullins, S.M. (American Physical Society, 2013)
      Knowledge of the exact microscopic structure of the 01 + ground state and first excited 02 + state in 150Sm is required to understand the branching of double β decay to these states from 150Nd. The detailed spectroscopy ...

    • The kinematic dipole in galaxy redshift surveys 

      Maartens, Roy; Clarkson, Chris; Chen, Song (IOP Publishing, 2018)
      In the concordance model of the Universe, the matter distribution { as observed in galaxy number counts or the intensity of line emission (such as the 21cm line of neutral hydrogen) - should have a kinematic dipole due ...