Conveners
Astrophysics: Extragalactic 1
- Brian van Soelen (University of the Free State)
Astrophysics
- Geoff Beck (University of Witwatersrand)
Astrophysics
- Konstantinos Kolokythas (North-West University)
Astrophysics
- Christo Venter (North-west University, Potchefstroom Campus)
Astrophysics
- Vanessa McBride (Office of Astronomy for Development)
Dark matter is believed to constitute the majority of the matter content of the universe, but virtually nothing is known about its nature. Physical properties of a candidate particle can be probed via indirect detection by observing the decay and/or annihilation products. While this has previously been done primarily through gamma-ray studies, the increased sensitivity of new radio...
Galaxy clusters are the largest gravitationally-bound structures in the Universe,
with their baryonic mass being distributed between the constituent galaxies and the
ionized plasma of their intracluster medium (ICM). As such, radio observations of
galaxy clusters are powerful tools for the detection of diffuse cluster-scale
synchrotron emission, which carries information about the cluster...
Gas flows are an important aspect of galactic feedback and the regulation of star formation in galaxies. Nearby starburst galaxies and LIRGs provide an extreme environment where feedback and the changes due to it can be studied in great detail. The aim of my project is to search for traces of outflows and inflows in a sample of nearby starburst galaxies and LIRGs in the SUNBIRD survey, and to...
Galaxy groups within the local Universe contain over 60% of all observable galaxies. Furthermore, galaxy groups host the majority of both baryonic and dark matter content in the Universe. Therefore galaxy groups are excellent laboratories for studying galaxy evolution. Of particular importance are the brightest group early-type galaxies (BGEs) roughly located at the centre of each group’s...
We present a study on the stellar populations and stellar ages of a sub-sample of far-infrared AGN and non-AGN green valley galaxies at 0.6 < z < 1.0 using the data from the COSMOS field. We used long-slit spectroscopy and derived stellar populations and stellar ages using the stellar population synthesis code “STARLIGHT” and analysed the available Lick/IDS indices, such as Dn4000 and...
Multiphase studies of the baryon cycle in groups at different stages of assembly combined with the multi-wavelength characterization of galaxies in the groups will inform us of the gas kinematics, group dynamics, galaxy properties, and subsequently the evolution of both groups and galaxies. While some works find increased star formation suppression events in groups, several others find...
Many observations have shown that the universe is expanding at an accelerated rate. The reason for this is, however, unknown. General relativity and standard cosmology seem to fail in explaining the early and late-time acceleration of the universe. There have been several suggested solutions to explain this phenomenon such as dark energy and modified theories of gravity, however none of which...
Recent work has shown that diffuse radio observations by MeerKAT - and eventually the SKA - are well suited to provide some of the strongest constraints yet on dark matter annihilations, particularly in dwarf spheroidal galaxies. To make full use of the observations by these facilities, accurate simulations of the expected dark matter abundance and diffusion mechanisms in these astrophysical...
Primordial black holes are a much-studied candidate for dark matter. In the mass regime where their conjectured Hawking evaporation is significant, they have been subject to many constraints via X-rays, gamma-rays, and even radio emission. Previously the Sunyaev-Zel'dovich effect (SZE) has been considered to place further limits on the primordial black hole abundance via the effects of their...
The next generation of telescopes in the gamma-ray, neutrino and radio domains have opened up a promising new avenue through which we can utilise multi-messenger astronomy to understand the nature of Dark Matter. An analysis of neutrino observations with KM3NeT and radio observations with MeerKAT illustrate this potential for DM indirect detection. A comparative analysis of gamma ray...
The discovering of the Cosmic Microwave Background (CMB) radiation in the sixties
and its subsequent interpretation, the numerous experiments that followed with the
enumerable observation data they produced. We see that the energy in the form of
radiation has the equation of state p = ρ/3. This applies to all massless particles. It is
also valid for massive particles when they are...
Astronomical data show that the observed universe is dominated by the dark sector, which is comprising of dark matter and dark energy. Since most of the existing work in the literature is limited to the study of background cosmological dynamics, the project studies late time cosmology where the universe is filled with dark fluids, namely dark matter and dark energy interacting with each other....
Gamma-ray bursts (GRBs) are highly energetic impulses of $\gamma-$rays that are classified into two major categories, long and short GRBs. Their distinction lies in their duration ($T_{90}$) which is calculated from the photon flux accumulation over time. The former lasts for more than 2s whilst the latter lasts for less than 2s with their prompt emission being in the keV to GeV energy band....
The recent accretion burst event in the high mass star forming region NGC6334I have given us rare insights into the mechanisms behind the formation of high mass $>8M_\odot$ stars. An important tracer in the study of star forming regions is astrophysical masers, especially 22 GHz water masers, which have also been studied in NGC6334I. There are still many open questions about water masers, such...
In this talk, we introduce photometric mode identification formula for pulsating stars. By considering radiative transfer equations, appropriate physical conditions and mathematical formulations, we derive a formula that describes the effect of pulsations in the light output of pulsating stars. For this formulation, we took into consideration the interaction of light with the different layers...
Millisecond pulsars (MSPs) are a class of pulsar with fast spin periods (<30 ms) and relatively low surface magnetic fields (~10^9 G). The Fermi Large Area Telescope (LAT) has detected gamma rays from more than 275 pulsars over the past 14 years, with over 125 being MSPs. Capitalising on this substantial growth in the population of detected gamma-ray MSPs that now includes bright pulsars...
The Neutron star Interior Composition Explorer (NICER) was installed aboard the International Space Station (ISS) in 2017 with the major aim of gaining a better understanding of the extreme nature and composition of neutron stars (NSs). With its exceptional sensitivity, it hopes to constrain the equation of state for these compact objects to high precision. Modelling thermal X-ray light curves...
AR Sco is a binary system that contains both a white and red dwarf. The spin rate of the white dwarf has been observed to slow down with time, analogous to rotation-powered radio pulsars; it has thus been dubbed a "white dwarf pulsar". We previously fit the traditional radio pulsar rotating vector model to linearly polarized optical data from this source, constraining the system geometry and...
The African Astronomical Society (AfAS) is a Pan-African Professional Society of Astronomers registered in South Africa as a non-profit, voluntary society. Our vision is to create and support a globally competitive and collaborative astronomy community in Africa. Our mission is to be the voice of astronomy in Africa and to contribute to addressing the challenges faced by Africa through the...
The Centre for Space Research / Physics group at the NWU has an optical telescope located at Nooitgedacht, a 45min drive from the Potchefstroom campus. Since 1998, it has been used for practical astronomy experiments for undergraduate 3rd-year physics students. Initially a 30cm telescope, it has been upgraded a decade ago to a 40cm telescope. Additionally, the telescope has been used for...
The physics building on the Potchefstroom campus has a new optical telescope on it. It is the old 30 cm that used to be at the Nooitgedacht observatory in 1998. We decided to give it a second life, obtained a new mount and refurbished it for public outreach purposes. This project was to setup a new telescope, from the roof anchoring to the electrical connection, to the balancing and polar...
Surveys like KELT and TESS searches for transiting extrasolar planets, and have found many potential candidates. The optical telescope at the Nooitgedacht Observatory is ideal for follow-up observations of these candidates, and to collect more data of specific promising candidates. Candidates that are suitable for observations were identified. The suitability of candidates depends on the...
In 2024, for the first time in the 100 year history of the International Astronomical Union, the General Assembly will take place on the African continent! This meeting encompasses more than logistics; it represents the vision of a dedicated cohort of African astronomers, and an opportunity to welcome the global astronomy community to Africa. We will present the current status of plans for...
Kes 75 (G29.7-0.3) is a Galactic composite supernova remnant with an embedded pulsar, PSR J1846-0258, that was discovered via X-ray timing. This pulsar powers a pulsar wind nebula that was seen to have expanded rapidly over the past several years. The pulsar’s inferred spin period and derivative thereof imply a canonical age of only 720 years and a very high spin-down luminosity of 8e36 erg/s....
Supernovae remnants (SNRs) are believed to be one of the prime sources of high-energy cosmic rays within our galaxy. SNRs are known to be efficient particle accelerators. Protons and electrons can be accelerated to very high energies of at least several tens of TeV both at the front and at the reverse shock of the remnant. These accelerated particles subsequently produce non-thermal...
Gamma-ray binaries are a small, but growing, subclass of high mass binary systems that show consistent gamma-ray emission up to very high energies. These systems all have compact objects in the mass range of black holes or neutron stars. For only two sources have are pulsed signals unambiguously detected, confirming a neutron star compact object. For the other systems, the binary parameters of...