Research Articles (Physics): Recent submissions
Now showing items 41-60 of 520
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Mightee: Deep 1.4 ghz source counts and the sky temperature contribution of star-forming galaxies and active galactic nuclei
(Oxford University Press, 2023)We present deep 1.4 GHz source counts from ∼5 deg2 of the continuum Early Science data release of the MeerKAT International Gigahertz Tiered Extragalactic Exploration survey down to S1.4GHz ∼15 μ Jy. Using observations ... -
Powder characteristics blending and microstructural analysis of a hot-pack rolled vacuum arc-melted gamma-tial-based sheet
(The Southern African Institute for Industrial Engineering, 2022)In the quest for cost-effective fabrication processes capable of producing sound γ-TiAl products, the microstructure and mechanical properties of a modified second-generation hot-rolled γ-TiAl-based alloy with nominal ... -
Effect of physical activity on coronary heart disease risk factors among firefighters: a scoping review protocol
(BMJ open, 2023)Introduction: Physical activity interventions have been used for various health conditions, including cardiovascular disease. However, the literature is still limited regarding the effect of physical activity on coronary ... -
Statistical recovery of 21 cm visibilities and their power spectra with gaussian-constrained realizations and gibbs sampling
(The Astrophysical Journal Supplement Series, 2023)Radio interferometers designed to probe the 21 cm signal from Cosmic Dawn and the Epoch of Reionization must contend with systematic effects that make it difficult to achieve sufficient dynamic range to separate the 21 cm ... -
Measurement of the evolving galaxy luminosity and mass function using clustering-based redshift inference
(Monthly Notices of the Royal Astronomical Society, 2023)We develop a framework for using clustering-based redshift inference (cluster-z ) to measure the evolving galaxy luminosity function (GLF) and galaxy stellar mass function (GSMF) using Wide-field Infrared Survey Explorer ... -
Figure rotation of dark haloes in cold dark matter simulations
(Oxford University Press, 2007)We investigate the figure rotation of dark matter haloes identified in cold dark matter (CDM) simulations.We find that when strict criteria are used to select suitable haloes for study, five of the 222 haloes identified ... -
Nonlinear galactic dynamos and the magnetic pitch angle
(American Astronomical Society, 2015)Pitch angles p of the large-scale magnetic fields B of spiral galaxies have previously been inferred from observations to be systematically larger in magnitude than predicted by standard mean-field dynamo theory. ... -
Reconstruction of dark energy and expansion dynamics using Gaussian processes
(IOP Publishing, 2012)An important issue in cosmology is reconstructing the effective dark energy equation of state directly from observations. With few physically motivated models, future dark energy studies cannot only be based on constraining ... -
Promoting physics and development in Africa
(American Institute of Physics, 2004)To excel in physics research in Africa is to conquer Mount Everest without the aid of additional oxygen. In a continent that lacks the infrastructure of research laboratories, technical support, and so forth, relatively ... -
Characterization of inpaint residuals in interferometric measurements of the epoch of reionization
(Monthly Notices of the Royal Astronomical Society, 2023)To mitigate the effects of Radio Frequency Interference (RFI) on the data analysis pipelines of 21 cm interferometric instruments, numerous inpaint techniques have been developed. In this paper, we examine the qualitative ... -
On the time delay between ultra-relativistic particles
(Elsevier, 2016)The time delay between the receptions of ultra-relativistic particles emitted simultaneously is a useful observable for both fundamental physics and cosmology. The expression of the delay when the particles travel through ... -
Simulating a full-sky high resolution Galactic synchrotron spectral index map using neural networks
(Monthly Notices of the Royal Astronomical Society, 2023)We present a model for the full-sky diffuse Galactic synchrotron spectral index with an appropriate level of spatial structure for a resolution of 56 arcmin (to match the resolution of the Haslam 408 MHz data). Observational ... -
Disentangling non-gaussianity, bias, and general relativistic effects in the galaxy distribution
(American Physical Society, 2012)Local non-Gaussianity, parametrized by f NL , introduces a scale-dependent bias that is strongest at large scales, precisely where general relativistic (GR) effects also become significant. With future data, it should ... -
Wide-angle effects in multi-tracer power spectra with Doppler corrections
(IOP Publishing, 2023). We examine the computation of wide-angle corrections to the galaxy power spectrum including redshift-space distortions and relativistic Doppler corrections, and also including multiple tracers with differing clustering, ... -
Mining mini-halos with MeerKAT I. Calibration and imaging
(Oxford University Press, 2023)Radio mini-halos are clouds of diffuse, low-surface brightness synchrotron emission that surround the Brightest Cluster Galaxy (BCG) in massive cool-core galaxy clusters. In this paper, we use third generation calibration ... -
Feature guided training and rotational standardization for the morphological classification of radio galaxies
(Oxford University Press, 2023)State-of-the-art radio observatories produce large amounts of data which can be used to study the properties of radio galaxies. However, with this rapid increase in data volume, it has become unrealistic to manually process ... -
Clustering of HI galaxies in the HI parkes all sky survey and arecibo legacy fast alfa survey
(Oxford University Press, 2011)We investigate the clustering of H I-selected galaxies in the Arecibo Legacy Fast ALFA Survey (ALFALFA) and compare results with those obtained for the H I Parkes All Sky Survey (HIPASS). Measurements of the angular ... -
Constraining primordial non-Gaussianity by combining next-generation galaxy and 21 cm intensity mapping surveys
(Institute for Ionics, 2023)Surveys of the matter distribution contain ‘fossil’ information on possible non-Gaussianity that is generated in the primordial universe. This primordial signal survives only on the largest scales where cosmic variance ... -
Constraining primordial non-gaussianity by combining next-generation galaxy and 21 cm intensity mapping surveys
(SpringerOpen, 2023)Surveys of the matter distribution contain ‘fossil’ information on possible non-Gaussianity that is generated in the primordialUniverse. This primordial signal survives only on the largest scales where cosmic variance ... -
Mightee-h i: Possible interactions with the galaxy NGC 895
(Oxford University Press, 2023)The transformation and evolution of a galaxy is strongly influenced by interactions with its environment. Neutral hydrogen (H i) is an excellent way to trace these interactions. Here, we present H i observations of the ...