Conveners
Astrophysics: Optical Astronomy I
- Alida Odendaal (University of the Free State)
Astrophysics: Optical Astronomy II / Astronomy for Development
- Helene Szegedi (University of the Free State)
Astrophysics: Gamma-ray / Multi-wavelength Astronomy I
- Brian van Soelen (University of the Free State)
Astrophysics: Cosmology / Dark Matter
- Christo Venter (North-west University, Potchefstroom Campus)
- Geoff Beck (University of Witwatersrand)
Astrophysics: Gamma-ray / Multi-wavelength Astronomy II / Non-specialist Talk
- Christo Venter (North-west University, Potchefstroom Campus)
Astrophysics: Division Meeting
- Christo Venter (North-west University, Potchefstroom Campus)
Astrophysics: Gamma-ray / Multi-wavelength Astronomy III / Radio Astronomy I
- Markus Bottcher (North West University)
Astrophysics: Radio Astronomy II / Gamma-ray / Multi-wavelength Astronomy IV
- Pieter Meintjes (University of the Free State)
Mr
Nazir-Ahmed Makda
(University of Cape Town)
26/06/2018, 10:00
Track D1 - Astrophysics
Oral Presentation
Ultra-Diffuse Galaxies(UDGs) are low surface brightness galaxies with a very low stellar mass component but their sizes are comparable to the Milky Way. To survive in the cluster environments where they have been observed these galaxies must contain significant amounts of dark matter as the strong tidal fields would normally tear diffuse low-mass galaxies apart. UDGs are hard to detect and...
Mr
Okkert Havenga
(North-West University)
26/06/2018, 10:20
Track D1 - Astrophysics
Oral Presentation
An important component of galaxy formation and evolution studies, is to accurately constrain their star formation histories (SFHs). While the SFHs of most massive early-type galaxies can be described using a single passively-evolving stellar component (Single Stellar Population [SSP]), there is a fraction of massive early-type galaxies in the centres of galaxy groups and galaxy clusters where...
Ms
Hester M. Schutte
(North-West University)
26/06/2018, 11:20
Track D1 - Astrophysics
Oral Presentation
The optical emission from most blazars is dominated by the polarised synchrotron radiation of relativistic electrons in the jet, but the thermal radiation from the accretion-disk and host galaxy also contributes towards the high and low frequency ends of the optical spectrum. As the accretion-disk and host galaxy emissions are expected to be unpolarised, they reveal their presence in a...
Dr
Getachew Mekonnen Mengistie
(Northwest University)
26/06/2018, 11:40
Track D1 - Astrophysics
Oral Presentation
In this talk a detailed review of stellar pulsation and radiative transfer equations are presented. Starting from the radiative transfer equations and by considering appropriate physical conditions and mathematical formulations, we derived a formula that describes the effect of pulsations in the light output of a star. We took into consideration the interaction of light with the different...
Mr
Thapelo Mokgadi
(Department of Physics, North West University)
26/06/2018, 12:00
Track D1 - Astrophysics
Oral Presentation
HD 68695 is a well known pre-main sequence star with well established infrared excess and emission in its hydrogen lines. In this paper we show for the first time that this star pulsates with periods around 23 minutes and the main amplitude of 3 mmag. We present the data collected using the new Mahikeng astronomical Observatory which confirms the frequencies that are found in the KELT data in...
Prof.
Thebe Medupe
(Department of Physics, North West University, Mafikeng)
26/06/2018, 12:20
Track D1 - Astrophysics
Oral Presentation
The new observatory of the North West University (MAO) houses a 40-cm MEADE LX200GPS ACF telescope with SBIG STT 8300M electronically cooled camera. It was officially launched on the 21 April 2018. This instrument is capable of detecting mili-magnitude changes in brightness of a star, and is thus suitable for the study of pulsating stars and exoplanet research. In this paper we present light...
Ms
Ashlynn Le Ray
(University of the Witwaterstrand)
27/06/2018, 10:00
Track D1 - Astrophysics
Oral Presentation
The star formation history (SFH) of the Universe is of fundamental importance to cosmology, not only to galaxy formation itself, but also for ongoing efforts to determine cosmological parameters and matter content of the universe. Measurement of the extragalactic background light (EBL) as a function of redshift can constrain models of the SFH, including the initial mass function(IMF) and dust...
Mr
Hassan Abdalla
(Centre for Space Research, North-West University, Potchefstroom 2520, South Africa)
27/06/2018, 10:20
Track D1 - Astrophysics
Oral Presentation
Several quantum-gravity theories predict that familiar concepts such as Lorentz symmetry can be broken at energies approaching the Planck energy scale.
Such extreme energies are currently unreachable by experiments on Earth, but for photons traveling over cosmological distances the accumulated deviations from the Lorentz symmetry may be measurable using the Cherenkov Telescope Array (CTA)....
Mr
Tej Chand
(Center for Space Research, North-West University Potchefstroom South Africa)
27/06/2018, 10:40
Track D1 - Astrophysics
Oral Presentation
The supermassive black holes in the centers of some active galaxies (AGN) eject powerful relativistic jets which propagate over kpc scales, showing no significant momentum loss. Both observational evidence as well as theoretical considerations from MHD simulations of jets suggest that they are radially stratified, with a fast inner spine surrounded by a slower-moving outer sheath. The...
Dr
Geoff Beck
(University of Witwatersrand)
27/06/2018, 11:20
Track D1 - Astrophysics
Oral Presentation
The Dark Matter Particle Explorer (DAMPE) satellite mission recently announced an excess is the observed electron/positron spectrum occurring around the TeV scale. This has been conjectured to be explicable in terms of the annihilation of a heavy leptophilic WIMP particle. Additionally, this hypothesis requires the presence of a dense clump of dark matter within 1 kpc of the Earth, in order...
Mr
Michael Sarkis
(University of the Witwatersrand)
27/06/2018, 11:40
Track D1 - Astrophysics
Oral Presentation
Potential links between astrophysical sources, such as gamma ray bursts and supernovae, and mass extinction events on Earth are of interest in the historical trajectory of life on our planet. There are strong arguments to suggest that these astrophysical sources can have several destructive effects, including depletion of atmospheric ozone and an increase in the radiation dose received by...
Dr
Fidy Andriamanankasina Ramamonjisoa
(University of the Free State)
27/06/2018, 12:00
Track D1 - Astrophysics
Oral Presentation
A precise measurement of the Cosmic Microwave Background (CMB) anisotropy has been one of the foremost concerns in modern cosmology as it provides a valuable information on the cosmology of the Universe. The estimation of the CMB power spectrum is complicated by different systematics. For the polarization experiments, the signals are rather fainter in comparison with the CMB total intensity,...
Mr
Geoff Beck
(University of Witwatersrand)
27/06/2018, 12:20
Track D1 - Astrophysics
Oral Presentation
What is the fate of a collapsing star? One possibility is that they evaporate due to Hawking radiation. The problem with this decay channel is that this perturbative phenomenon takes place on time scales far too large to be of astrophysical concern. We consider the exciting and exotic proposal of Planck stars put forth by Carlo Rovelli and others which posits new ways of probing quantum...
Ms
Heba Abdulrahman
(North-West University)
27/06/2018, 12:40
Track D1 - Astrophysics
Oral Presentation
Theoretical physics in general and cosmology in particular have faced some challenges due to the recent observations in cosmology and astronomy, such as the discovery of the accelerated cosmic expansion and the existence of dark matter and dark energy. Einstein’s theory of General Relativity (GR) together with the standard model of cosmology fall short of giving any explanations for...
Carlo van Rensburg
(North West University Potchefstroom)
27/06/2018, 14:00
Track D1 - Astrophysics
Oral Presentation
We present results from a spatio-temporal leptonic emission code that models the spectral energy distribution (SED) from and the radiation spectrum at different positions in a pulsar wind nebula (PWN). The model includes a time- and spatially-dependent magnetic field, spatially-dependent bulk particle speed implying convection and adiabatic losses, diffusion, as well as radiative losses and...
Mr
Louis Du Plessis
(NWU, Potchefstroom, Department of Physics)
27/06/2018, 14:20
Track D1 - Astrophysics
Oral Presentation
Marsh et al. (2016) detected radio and optical pulsations from the binary system AR Scorpii(AR Sco). This system, with a orbital period of 3.55h, is composed of a cool, low-mass companion star and a white dwarf with a spin period of 1.97min. Optical observations by Buckley et al. (2017) showed that the polarimetric emission from the white dwarf is strongly linearly polarised (~ 40%) with...
Dr
Markus Bottcher
(North-West University)
27/06/2018, 14:40
Track D1 - Astrophysics
Oral Presentation
The joint detection of a gravitational-wave event from a binary-neutron-star merger, GW170817, by LIGO/VIRGO and a short gamma-ray burst, GRB170817A, by Fermi-GBM and INTEGRAL, ushers in a new era of true multi-messenger astronomy. It triggered the most intensive, world-wide multi-wavelength follow-up observing campaign ever conducted to date, involving almost 3,700 astronomers around the...
Prof.
Christo Venter
(North-west University, Potchefstroom Campus)
, Dr
Du Toit Strauss
(Centre for Space Research, North-West University)
27/06/2018, 15:40
Mr
Izak van der Westhuizen
(University of the Free State)
28/06/2018, 10:00
Track D1 - Astrophysics
Oral Presentation
Relativistic hydrodynamic simulations have become a powerful tool used to simulate the dynamics of jets produced in radio-loud Active Galactic Nuclei (AGN). These AGN jets consist of plasma ejected by a central engine moving at relativistic velocities. Observational studies of AGN jets have shown that they emit variable emission over the whole of the electromagnetic spectrum. The spectral...
Prof.
Christo Venter
(North-west University, Potchefstroom Campus)
28/06/2018, 10:20
Track D1 - Astrophysics
Oral Presentation
The Fermi Large Area Telescope has detected more than 200 gamma-ray pulsars. Many of them are in binary systems, and a subset of these comprise the "spider binary" class, including black widows and redbacks. The latter systems consists of energetic pulsars and companion stars that are in tight binary orbits. The two stellar winds interact with each other, forming an intrabinary shock and...
Mr
Eric Maina
(Rhodes University)
28/06/2018, 10:40
Track D1 - Astrophysics
Oral Presentation
The tilted-ring model describes a galaxy as a set of rotating rings, each of which is parameterized by a set of parameters representing surface brightness, rotation speed, and orientation of the disk. Our implementation of the tilted-ring model, TiRiFiC ("Tilted-Ring-Fitting-Code") works by directly fitting galaxy models to spectroscopic data cubes (as observed with the SKA and its...
Mr
Gift Sichone
(Rhodes University)
28/06/2018, 11:20
Track D1 - Astrophysics
Oral Presentation
A fraction of galaxy clusters host diffuse,Mpc-scale,low surface brightness emissions named "radio halos",that spatially correlate with the diffuse X-ray emission. Current models indicate that radio halos are connected to the galaxy cluster merger history: radio emission is due to particles that are re-accelerated to relativistic energies via turbulence induced via cluster mergers.
Here we...
Mbou Sob Ulrich Armel
(Rhodes University)
28/06/2018, 11:40
Track D1 - Astrophysics
Oral Presentation
Calibration in radio astronomy is the step during which all systematic errors and ionospheric curruptions, are estimated and removed from the observed data. This consists of solving for all propagation effects, i.e.~Jones matrices, which minimizes the difference between the measured and the model data using a mathematical framework known as the Radio Interferometric Measurement Equation...
Mr
James Chege
(Rhodes University)
28/06/2018, 12:00
Track D1 - Astrophysics
Oral Presentation
The Precision Array to Probe the Epoch of Reionization (PAPER, http://eor.berkeley.edu) was built to measure the redshifted 21-cm line from cosmic reionization. Here, I will present the analysis of the last season of PAPER observations, with particular focus to image and characterize the foreground emission, a crucial task in order to detect the much fainter 21-cm emission.
Mr
Athanaseus Ramaila
(Rhodes University)
28/06/2018, 12:20
Track D1 - Astrophysics
Oral Presentation
Radio interferometry software packages have grown sophisticated enough that we can now begin to address some of the imaging issues that are posed by the next generation of radio telescopes, most notably the MeerKAT and Square Kilometre Array (SKA). The main objective of this project is to develop a framework that allows the evaluation of deconvolution algorithms and imaging techniques using a...
Dr
Brian van Soelen
(University of the Free State)
28/06/2018, 12:40
Track D1 - Astrophysics
Oral Presentation
LMC P3 is the most recently discovered, and the most luminous, γ-ray binary. The source was discovery with Fermi-LAT γ-ray observations which showed a 10.301 ± 0.002 day period. The γ-ray emission is associated with the previously detected point-like X-ray source CXOU J053600.0-67350, within the supernova remnant DEM L241, and this binary was previously classified as a high mass X-ray binary...
