Physics and Astronomy: Recent submissions
Now showing items 141-160 of 533
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Energy-momentum tensor and helicity for gauge fields coupled to a pseudoscalar inflaton
(University of the Western Cape, 2019)We study the energy-momentum tensor and helicity of gauge fields coupled through $g \phi F \tilde{F}/4$ to a pseudo-scalar field $\phi$ driving inflation. Under the assumption of a constant time derivative of the background ... -
Rotational structures in 196Hg
(University of the Western Cape, 2019)High spin states in 196 Hg were populated in the 198 Pt (α,6n) reaction at 65 MeV and γ −γ coincidence measurements were performed using the AFRODITE array at iThemba LABS. The level scheme was extended and new rotational ... -
On the primordial origin of the smoothing excess in the Planck temperature power spectrum in light of LSS data
(IOP Publishing, 2022)The Planck DR3 measurements of the temperature and polarization anisotropies power spectra of the cosmic microwave background (CMB) show an excess of smoothing of the acoustic peaks with respect to ΛCDM, often quantified ... -
Cosmological constraints on post-Newtonian parameters in effectively massless scalar-tensor theories of gravity
(2019)We study the cosmological constraints on the variation of Newton’s constant and on post-Newtonian parameters for simple models of the scalar-tensor theory of gravity beyond the extended Jordan-BransDicke theory. We restrict ... -
Imprints of temperature fluctuations on the z ∼ 5 Lyman-α forest: a view from radiation-hydrodynamic simulations of reionization
(Oxford academic, 2019)Reionization leads to large spatial fluctuations in the intergalactic temperature that can persist well after its completion. We study the imprints of such fluctuations on the z ∼ 5 Ly α forest flux power spectrum using ... -
IQ-Collaboratory 1.1: The Star-forming Sequence of Simulated Central Galaxies
(The astrophysical journal, 2019)A tightly correlated star formation rate (SFR)–stellar mass relation of star-forming galaxies, or star-forming sequence (SFS), is a key feature in galaxy property-space that is predicted by modern galaxy formation models. ... -
Asteroseismology of Massive Stars with the TESS Mission: The Runaway β Cep Pulsator PHL 346 = HN Aqr
(The Astrophysical journal letter, 2019)We report an analysis of the first known β Cep pulsator observed by the Transiting Exoplanet Survey Satellite (TESS) mission, the runaway star PHL 346 = HN Aqr. The star, previously known as a singly periodic pulsator, has ... -
Multi-instrument observations of large-scale atmospheric gravity waves/traveling ionospheric disturbances associated with enhanced auroral activity over Svalbard
(Elsevier, 2019-09-03)This study reports on observations of large-scale atmospheric gravity waves/traveling ionospheric disturbances (AGWs/TIDs) using Global Positioning System (GPS) total electron content (TEC) and Fabry–Perot Interferometer’s ... -
Preface Metamorphism and Orogenic belts—response from micro- to macro-scale
(Springerlink, 2019)The geological toolbox for the analysis of orogenic processes has seen substantial additions over the recent decades. Major advances have been made in the ability to simulate geological conditions and processes by computer ... -
Surveys with small optical telescopes
(Oxford academic, 2019)odern astrophysics owes its existence to small-telescope surveys dating back to the 18th century, for example Flamsteed (1725). In the 19th century, Argelander’s survey based on visual observations with small telescopes and ... -
Semi-analytic forecasts for jwst – ii. Physical properties and scaling relations for galaxies at z = 4–10
(Oxford academic, 2019)The long anticipated James Webb Space Telescope (JWST) will be able to directly detect large samples of galaxies at very high redshift. Using the well-established, computationally efficient Santa Cruz semi-analytic model, ... -
Probing primordial features with the primary CMB
(Elsevier, 2019)We propose to study the imprint of features in the primordial power spectrum with the primary CMB after the subtraction of the reconstructed ISW signal from the observed CMB temperature angular power spectrum. We consider ... -
Hierarchiral 4-tetranitro copper(II)phthalocyanine based metal organic framework hybrid composite with improved electrocatalytic efficiency towards hydrogen evolution reaction
(Elsivier, 2019)A novel hybrid-hybrid nanocomposite based on 4-tetranitro copper(II)phthalocyanine (TNCuPc) grown on metal organic frameworks (MOF) as a noble metal-free catalyst for hydrogen evolution reaction (HER) was developed by a ... -
HELP: a catalogue of 170 million objects, selected at 0.36–4.5 μm, from 1270 deg2 of prime extragalactic fields
(Oxford University Press, 2019)We present an optical to near-infrared (NIR) selected astronomical catalogue covering 1270 deg2. This is the first attempt to systematically combine data from 23 of the premier extragalactic survey fields – the product of ... -
SCUBA-2 observations of candidate starbursting protoclusters selected by Planck and Herschel-SPIRE
(Royal Astronomical Society, 2019)We present SCUBA-2 850 μm observations of 13 candidate starbursting protoclusters selected using Planck and Herschel data. The cumulative number counts of the 850 μm sources in 9 of 13 of these candidate protoclusters show ... -
Evolution of the chemical composition of Sn thin films heated during x-ray photoelectron spectroscopy
(2019)High-vacuum XPS have been used to analyse the surface modification of a 3 nm-thick Sn thin film on Si (100) before and after annealing up to 450 °C. Increasing the XPS stage temperature led to a reduction in the amount of ... -
The WISE Extended Source Catalog (WXSC). I. The 100 Largest Galaxies
(University of the Western Cape, 2019)We present mid-infrared photometry and measured global properties of the 100 largest galaxies in the sky, including the well-studied Magellanic Clouds, Local Group galaxies M31 and M33, the Fornax and Virgo galaxy cluster ... -
Probabilistic learning for pulsar classification
(IOP Publishing, 2022)In this work, we explore the possibility of using probabilistic learning to identify pulsar candidates. We make use of Deep Gaussian Process (DGP) and Deep Kernel Learning (DKL). Trained on a balanced training set in ... -
Hiflow: Generating diverse hi maps and inferring cosmology while marginalizing over astrophysics using normalizing flows
(IOP Publishing, 2022)A wealth of cosmological and astrophysical information is expected from many ongoing and upcoming large-scale surveys. It is crucial to prepare for these surveys now and develop tools that can efficiently extract ... -
Patterns of primary beam non-redundancy in close-packed 21 cm array observations
(Oxford University Press, 2021)Radio interferometer arrays such as HERA consist of many close-packed dishes arranged in a regular pattern, giving rise to a large number of ‘redundant’ baselines with the same length and orientation. Since identical ...