Conveners
Science & Engineering: 1 Cosmology
- Kavilan Moodley (University of KwaZulu-Natal)
Science & Engineering: 2 Instrumentation & Other
- Brian Chaboyer (Dartmouth College and SALT)
Science & Engineering: 3 Galaxies I
- Christopher Conselice (Manchester University, England (UK))
Science & Engineering: 4 Galaxies II
- Jacobus Diener (BIUST)
Science & Engineering: 5 Transients
- Patrick Woudt (University of Cape Town, IDIA)
Science & Engineering: 6 Galaxy Clusters
- There are no conveners in this block
Science & Engineering: 7 Stars and Star Formation I
- There are no conveners in this block
Science & Engineering: 8 Stars and Star Formation II
- There are no conveners in this block
Science & Engineering: 9 Machine Learning and Techniques
- Nadeem Oozeer (SARAO)
Previous studies of galaxy formation have shown that only 10 per cent of the cosmic baryons are in stars and galaxies, while 90 per cent of them are missing. In this talk, I will present three observational studies that coherently find significant evidences of the missing baryons. The first is the cross-correlation between the kinetic Sunyaev-Zeldovich maps from Planck with the linear...
Gravitational lensing provides a powerful probe of the global mass properties of galaxies, which are best tested using observations at extremely high angular resolution. In addition, through detailed observations of the lensed images, it is possible to place tight constraints on the nature of dark matter through measuring the abundance and properties of low mass haloes via their subtle...
This study investigates the formation of non-linear ion-acoustic solitary structures (IASSs) in magnetized plasmas consisting of inertial cold ions, superthermal electrons, and positrons. The reductive perturbation method was employed to derive the Korteweg-de Vries (KdV) equation, and the steady state solution of the KdV equation was obtained, providing a framework for exploring the solitary...
Interacting Dark Energy (IDE) models, where dark matter and dark energy interact through a non-gravitational coupling, have recently regained attention as late-time cosmic tensions persist and new datasets hint at possible dynamical dark energy and deviations from ΛCDM.
In this talk, we will present observational constraints on a broad class of linear and non-linear IDE models using some of...
We study cosmic magnification beyond lensing in a late-time universe dominated by quintessence and cold dark matter. The cosmic magnification angular power spectrum, especially going beyond the well-known lensing effect, provides an independent avenue for investigating the properties of quintessence, and hence, dark energy. By analysing the magnification power spectrum at different redshifts,...
The redshifted 21 cm line is a powerful probe of the epoch when the first stars and galaxies were born and, consequently, reionized the intergalactic medium. In this talk I will present upper limits on the redshifted 21 cm line obtained through observations with the Hydrogen Epoch of Reionization Array showing that the intergalacticm medium was heated above the adiabatic limit before z ~ 8. I...
A new method for optimizing the layout of radio telescope antenna arrays will be presented. These methods are are based on the SVD of the telescope operator, and provide a flexible method for choosing optimal antenna positions. The method is applied to choosed antenna positions for the TART telescope, and this has led to the latest spiral antenna designs used in the African TART telescopes in...
Since 1907, a lot of valuable and important scientific research work has been done using the 30-inch Reynolds refractor at Helwan, and Kottamia 74-inch telescope in Egypt. Kottamia telescope is the only one at its size in the Middle East and the second in Africa.
In my talk, the Egyptian current observatory facilities will be presented. The talk will be somewhat technical and is related to...
Small near-Earth asteroids (NEAs $<$ 150m) represent the most numerous yet least understood segment of potentially hazardous objects in our Solar System. Their rapid fading after discovery makes it challenging to obtain sufficient follow-up observations for characterisation studies, leaving a critical gap in our knowledge of their taxonomic distribution. We present results from a robotic...
The study emphasizes a switchable characteristic of narrow-band coupled resonators of a dual-band filter developed based on the reactance transformation method as a single filter structure. The filter is realized on Mercurywave 9350 multi-layer substrate. The substrate was chosen for various reasons, including its relatively constant permittivity over frequency. The designs feature a dual-path...
MeerKLASS is a single dish HI intensity mapping survey of the MeerKAT Telescope. Probing the 21 cm signal is coupled with challenges from foregrounds and radio frequency interferences (RFI) which contaminates the data, and in turn our cosmological signal. The MeerKLASS collaboration has produced a detection of the HI cosmological signal using cross-correlations with galaxy surveys. However,...
Computational methods underpin much of modern research, yet authors of these methods have not always received appropriate credit for their work, and locating reliable, reusable software can be challenging for both researchers and students. The Astrophysics Source Code Library (ASCL; ascl.net) addresses these issues by providing a free, curated registry of openly available software used in...
Quasars have historically been classified into two distinct classes, radio-loud (RL) and radio-quiet (RQ), taking into account the presence and absence of relativistic radio jets, respectively. Although different attempts were made to unify these two classes, there is a long-standing open debate involving the possibility of a real physical dichotomy between RL and RQ quasars. To address this,...
One of the fundamental challenges in understanding dwarf irregular galaxies is determining how their HI structure and kinematics influence their star formation activity and dark matter distribution. The MHONGOOSE survey, using deep MeerKAT observations, provides an unprecedented opportunity to study these processes in detail. In this talk, I will present an analysis of the HI distribution,...
Within the MIGHTEE deep continuum images, we discovered one of the rarest subpopulations of radio galaxies (RGs) called triple-double radio galaxies (TDRGs). They are characterised by three pairs of radio lobes, each pair of lobes representing an episode of nuclear activity. TDRGs are key tools to understand the duty cycle of RGs. In this work, we report the seventh known TDRG, J022248−060934....
Understanding the co-evolution of supermassive black holes and star formation remains a fundamental challenge in galaxy evolution studies. Radio emission in galaxies is often a complex mixture of star formation and Active Galactic Nuclei (AGN) activity, requiring milli-arcsecond resolution to disentangle. We present the first results from the VLBI Lockman Hole Survey, a deep wide-field...
Understanding the origin and working modes of the cessation of star formation in galaxies that lead to the passively evolving population is vital in galaxy evolution studies. The environment of galaxies is a critical aspect of these investigations, as the fraction of star-forming galaxies is the lowest inside galaxy clusters. At the same time, the fraction of passive galaxies is the highest....
We present deep MeerKAT follow-up observations (16 hrs with the 32k correlator) of an extraordinary, extremely low column-density HI disk uncovered in the SARAO MeerKAT Galactic Plane Survey (SMGPS). MeerKAT reveals a vast, patchy, spiral-like structure dominated by exceptionally low column densities (10^18 – 10^20/cm^2). Despite its modest HI mass, the disk reaches an astonishing ~260...
The origin and impact of radio emission in radio-quiet quasars has remained ambiguous for decades, largely due to limitations of all-sky, low-resolution surveys. Leveraging new, sensitive sub-kpc–to–kpc scale radio imaging from the Quasar Feedback Survey (QFeedS), we are now resolving the structures that drive feedback at the heart of massive galaxies. Using e-MERLIN, we mapped radio emission...
Blazars, a subclass of active galactic nuclei (AGN) with relativistic jets aligned close to our line of sight, dominate the extragalactic gamma-ray sky and are characterised by pronounced variability across the electromagnetic spectrum. Millimetre observations are particularly valuable as they probe emission regions close to the base of the jet, where high-energy activity is thought to...
The current ∧CDM model of hierarchical galaxy formation highlights the importance of galaxy
interactions and mergers in the evolution of galaxies. Galaxies undergo cycles of star forma-
tion and AGN activity induced by mergers and interactions as they evolve towards early-type
quiescent objects. However, this has not been observationally well supported. In this work, we
aim to go a step...
I describe the cosmic evolution of galaxy discs from z~6 to the present using bars as a sign post of galaxy evolution. I will describe the observations and analysis from two fundamental surveys I have led, namely COSMOS and S4G which together form the foundational datasets for the study of galactic structure from high redshifts to the local Universe. We find that galaxy disk assembly and...
We present a kinematic and mass-modelling analysis of the nearby late-type galaxy NGC 45 using high-quality HI observations from the IMAGINE survey, complemented by a stellar mass profile derived from Spitzer IRAC 1 (3.6 μm) imaging. From the well-resolved HI cube, we construct a rotation curve and decompose it into stellar, gaseous, and dark matter (DM) components. Mass models are fitted...
Angular momentum is a fundamental property that shapes the evolution of disc galaxies, strongly influencing the internal mechanisms that regulate star formation. In an ideally closed system, angular momentum would be conserved; however, because galaxies continuously interact with their environments, their angular momentum content is expected to change over time. Despite extensive work, a clear...
The second data release (DR2) of the Indian Pulsar Timing Array (InPTA) represents a major milestone in precision pulsar timing using the upgraded Giant Metrewave Radio Telescope (uGMRT). Combining seven years of simultaneous dual-band observations (300–500 MHz and 1260–1460 MHz) of 27 millisecond pulsars (MSPs), InPTA DR2 provides one of the most sensitive low-frequency datasets currently...
Stellar occultations, in which an asteroid transits across the line of sight to a background star, provide one of the most accurate ground-based methods for determining asteroid diameters, shapes, and possible companions. This study reports on a series of predicted asteroid occultation events monitored using the 1.88-m Kottamia Telescope in Egypt. High-cadence CCD imaging and photometric...
Massive X-ray binaries are intriguing astrophysical systems that provide valuable insights into some of the most extreme physical processes in the universe. These binary systems offer a unique opportunity to study the end products of stellar evolution, specifically neutron stars and black holes. As precursors to gravitational waves and short gamma-ray bursts, massive X-ray binaries are...
We present a detailed single-pulse study of the long-period pulsar PSR J2129+4119 using high-sensitivity FAST observations. Despite locating well below the traditional death line, the pulsar exhibits sustained and multi-modal emission behavior, including nulls, weak pulses, regular emission, and occasional bright pulses. The nulling fraction is measured to be $8.13\% \pm 0.51\%$, with null...
Fast Radio Bursts (FRBs) are bright, millisecond radio pulses occurring at cosmological distances. The nature of these sources is still unknown. Upon localisation of the repeating FRBs, luminous compact persistent radio sources (PRSs) can be detected in some cases. Studying the PRSs may give us clues about the immediate environments of the FRBs, which in turn provides insights into the nature...
As part of the TRAnsients And PUlsars with MeerKAT (TRAPUM) Large Survey Project, we have been using the sensitive MeerKAT telescope to search for extragalactic radio pulsars in the Large Magellanic Cloud (LMC). The LMC, located about 50 kpc from Earth, is our closest galactic neighbour and an excellent environment for pulsar population studies. It has lower metallicity, enhanced star...
We present MeerKAT HI observations of galaxies in the core of the Shapley Supercluster, one of the most massive structures in the local Universe. Our sample of HI-detected galaxies in A3558 and SC1329 allows us to examine how cold-gas content and star formation evolve in an extreme, high-density environment. Galaxies in the SSC-core lie systematically below field HI scaling relations, showing...
Galaxy clusters are the largest gravitationally bound structures in the universe, hosting megaparsec-scale diffuse radio emission in the form of halos and relics. These non-thermal synchrotron sources trace shocks, turbulence, and magnetic fields in the intracluster medium, providing a unique window into particle acceleration processes and cosmic magnetism. The upcoming Square Kilometre Array...
Galaxy groups and clusters retain a fossil record of their formation history in the chemical composition of their hot intragroup and intracluster gas. Upcoming high-resolution X-ray missions, such as Athena’s X-IFU, will provide spatially resolved abundance measurements for multiple elements. In this work, I combine the cosmological hydrodynamical simulation Simba-C, which incorporates the...
The formation and evolution of the Milky Way has been a long-standing subject of interest. Stars in the thick and thin disc components overlap in the intermediate-age regime, unlike at the extreme ends of the metallicity versus alpha-abundance spectrum, where both populations are well separated. In this study, we introduce a new technique that utilises the [Na/Fe] versus stellar age relation...
We present preliminary results from a study of 13 mini-halos (MHs), including candidate sources from the MeerKAT Galaxy Cluster Legacy Survey (MGCLS). Mini-halos are diffuse, faint radio sources typically found in relaxed galaxy clusters, with their origins attributed to either hadronic interactions or turbulent re-acceleration processes. Using \texttt{oxkat}, we reduced archival L-band MGCLS...
This project conducts a comparative analysis of galaxies in the Fornax
main cluster and its Fornax A subcluster. Dominated by NGC 1399,
Fornax is the most massive southern hemisphere cluster within 20Mpc.
The NGC 1316 subcluster, gravitationally bound and potentially on its
first infall, exhibits intense star formation, providing a unique laboratory
to study how cluster assembly affects...
Full Stokes polarisation measurements of a sample of star-forming regions have been observed in the C-band with the Green Bank 100m telescope. Results of the polarisation properties of the detected 4.7 and 6.0 GHz excited OH masers will be reported, and what can be inferred about the magnetic fields in these regions. Besides the masers, there is also some thermal emission from some of these...
New CCD light curves in the V, Rc, and Ic bands of the W UMa-type eclipsing binary system KAO-EGYPT J214258.21+440520.2 were obtained using the 1.88 m reflector telescope at Kottamia Astronomical Observatory (KAO), Egypt, on September 27 and 28, 2016. Based on these observations, new times of minima and a revised ephemeris have been determined. The geometric and photometric parameters of the...
In this presentation we are going to develops mathematical equations which explain how stellar oscillations interact with convection. The research defines essential mathematical components needed to model stellar oscillation responses to convective effects through the integration of linearized pulsation equations (momentum, continuity, and energy) with Mixing-Length Theory equations for...
Large magnetic reconnection–driven flares are ubiquitous in young, pre-main-sequence stars, yet their impact on the chemistry of protoplanetary discs remains almost entirely unconstrained observationally. Chemical evolution at disc scales, where grains form, migrate, and assemble into future planets, is expected to respond rapidly to flare-driven X-ray, UV, and suprathermal particle...
We present a multi-wavelength analysis of the massive star-forming region G345.50+0.35 using MeerKAT observations and high-resolution ALMA archival data to investigate the morphology, kinematics, and dynamical ages of gas and dust in this region. Ionized gas traced by free–free emission reveals three sources labelled A, B, and C with source C exhibiting a morphology indicative of triggered...
Interacting galaxies provide the critical mechanism for linking young massive star clusters (YMCs) and neutral hydrogen (HI): the intense starbursts they trigger form YMCs, and the subsequent stellar feedback from these clusters (e.g., stellar winds, supernovae) dramatically sculpts the surrounding HI gas. This impact of stellar feedback on the HI distribution and kinematics is a critical, yet...
ESA’s PLATO mission will provide highly precise photometric data, necessitating equally accurate and consistent spectroscopic information to precisely characterise stars and their orbiting planets. Currently, many gas-giant exoplanet host stars in the PLATO southern prime field designated for the mission lack uniformly derived atmospheric and chemical parameters. This inconsistency in...
This research offers a stochastic framework for the stellar helium burning network (SHBN), combining Itô stochastic differential equations (SDEs) with multiplicative white noise to approximate turbulence and quantum fluctuations in stellar interiors. We construct a semi-analytical power series solution linked with stochastic correction via the exponential Itô factor, confirming findings...
We investigate the periodic variability of 6.7 GHz class II methanol masers in the high-mass star-forming region G174.20-0.08 using multi-epoch observations from the Hartebeesthoek Radio Astronomy Observatory (HartRAO). These masers trace dynamic processes near massive protostars. Our analysis reveals repeating flux variations, possibly linked to accretion bursts, binary motion, or disk...
We present high-resolution S-band (3.1GHz) radio continuum observations of eleven massive young stellar objects (MYSOs), most of which exhibited extended emission in the SARAO MeerKAT Galactic Plane Survey conducted at 1.3GHz. The improved angular resolution of ∼3.1" at 3.1GHz enabled the detection of all the jets with many resolved in to multiple components, allowing detailed analysis of...
Star formation is a multi-scale process which is regulated by many different environmental factors. Gravity, global and local gas dynamics, radiation and feedback processes, turbulence and magnetic fields all play a role in regulating star formation rates and the resulting star population. We attempt to further constrain the ‘star formation recipe’ by determining how the large-scale dynamics...
Zeeman splitting observed from maser line profiles, enables the line-of-sight magnetic field magnitude to be ascertained. And the maser’s linear polarization position angle provides the magnetic field orientation in the reference-frame perpendicular to the observer. This detail, together with changing maser linear and circular polarization, has facilitated the creation of model where we are...
Globular clusters are among the most well-studied objects in astronomy (Renaud, 2018). The continued study thereof will likely reveal key insights into the spatial, dynamical and chemical properties of galaxies (particularly the Milky Way), stellar formation and evolution, as well as assist in applying constraints on dark matter and initial mass function models.
My Master’s project was...
Telescopes such as the Square Kilometre Array (SKA) and Vera C. Rubin Observatory (LSSRT) will produce more data than astronomers can analyse manually. Machine learning, being data-driven, is increasingly being applied in astronomy. Unsupervised machine learning, in particular, is a powerful approach for finding patterns and anomalies automatically, but struggles with high-dimensional data...
Simultaneous detections of Gamma-Ray Bursts (GRBs) by the Fermi Gamma-ray Burst Monitor (GBM) and the Fermi Large Area Telescope (LAT) instruments are crucial for understanding the full spectral evolution of relativistic jets. Addressing the delay in official catalog releases, we developed a scalable machine learning pipeline to identify coincident events in real-time. By performing a...
Astronomical seeing refers to the clarity and sharpness of celestial observations, governed largely by atmospheric turbulence influenced by dust, humidity, wind, and temperature fluctuations. Poor seeing conditions distort images, degrade measurement accuracy, and lead to inefficient use of valuable telescope time. These atmospheric fluctuations also critically affect geodetic systems such as...
We introduce OJALA (Optimizing J-PAS Astronomy for Large-scale Analysis), a Transformer-based foundation model specifically designed to analyze narrow-band photometry from the Javalambre Physics of the Accelerating Universe Astrophysical Survey (J-PAS). The model is pre-trained on synthetic photometry derived from 19.6 million spectra from the Dark Energy Spectroscopic Instrument (DESI)....
Hyperspectral satellite missions create opportunities for plant health monitoring from space. The German Environmental Mapping and Analysis Program (EnMAP) is a spaceborne hyperspectral mission that provides dense spectral coverage for each ground pixel. This study proposes to use EnMAP data for plant pest and disease detection, an application area that remains largely unexplored. Previous...
The constancy of fundamental natural constants (FNCs), such as the fine-structure constant (α), the gravitational constant (G), and the speed of light (c), is a foundational pillar of modern physics. However, persistent observational anomalies—most notably the > 5σ Hubble Tension between early- and late-universe measurements of the Hubble constant—increasingly challenge this paradigm. While...
A variety of high-energy pulsar models have been developed over the years. This theoretical activity was prompted by a consistent stream of pulsar discoveries, the rate of which rapidly increased since the launch of the Fermi Large Area Telescope (LAT) in 2008. Indeed, the recent Third Pulsar Catalog (3PC) now contains light curves and spectra of nearly 300 pulsars, along with some interesting...
In a pulsar, there are gaps and difficulties in our knowledge of glitches, mainly because of the absence of information about the physics of the matter of the star. This has motivated several authors to suggest dynamical models that interpret most of the astronomical data. Many predictions are based on the assumption that the inner part is analogous to the structure of matter of superfluids....
We present a self-contained re-analysis of the five frequency-band all sky observations from the Wilkinson Microwave Anisotropy Probe (WMAP) to investigate in detail the characteristics of Galactic synchrotron emission. The K, Ka, Q, V and W maps are homogenised in angular resolution and pixelisation, and are converted from thermodynamic temperature units to Rayleigh-Jeans (antenna)...
An accretion disk plays a crucial role in various astrophysical phenomena. Dwarf nova (DN) outbursts in an accreting white dwarf binary provide the simplest laboratory for the time-dependent behavior of accretion disks. Most energetic DN outbursts (superoutbursts) are accompanied by small modulations known as superhumps, which change their periods and profiles over a superoutburst. Despite...
We present a new cosmological model that we have coined the---Eternal Universe Model (EU-model). At a prima facie level, this model resembles the traditional Friedmann Universe model (also known as the FLRW model, Lambda-CDM model, or Concordance Model) but eliminates the assumption of temporal homogeneity. Specifically, we subtly modify the FLRW metric by allowing the rate at which time...
We investigate the dynamics and energetics of selected peculiar radio galaxies (bent-tailed, asymmetric, and disrupted sources). We take particular interest in the influence of the local environment on the morphology and properties of these radio galaxies by comparing the characteristics of the galaxies themselves with their cluster environment, sampling a variety of representative cluster...
MAXI J1535-571 accretion flow exhibits optically thin (sub-Keplerian) and optically thick (Keplerian) plasma. The manifestation of soft photons and their interception and Comptonization by hot electrons produce hard X-rays, and cause the Compton cloud/post-shock region to change periodically. As a result, propagating oscillatory shock waves (Quasi-periodic oscillations; QPOs) were produced....
The Zambia Ground Receiving Station (GRS) is the country’s first satellite data acquisition facility, established on a 7.3-m antenna platform to strengthen national infrastructure for Earth observation. The system is engineered to track and receive data from low-Earth-orbit satellites, including TERRA/AQUA, MODIS, Landsat 8, and Landsat 9, through dedicated S-band and X-band subsystems. The...
One of the most effective observational instruments for understanding the universe's formation, composition, and evolution is the Cosmic Microwave Background (CMB). However, increasing data volumes, complex noise structures, and the need for high-precision cosmological inference present growing challenges for conventional CMB processing methods. The goal of this project is to develop an...
Dense pre-stellar molecular clumps have been well studied extensively in the Milky, however, little has been done in understanding prestellar mollecular clumps in external galaxies due to their distance and low resolution telescopes. This leaves an important gap in understanding how stars form under different galactic environments, with the coming of ALMA telescope which offers high...
The sudden increase in a pulsar's spin frequency,referred to as a pulsar glitch,offers valuable insights into the internal dynamics of neutron stars.These glitches occur from the rapid unpinning of superfluid vortices in the inner crust,resulting from a differential rotation lag between the crust and superfluid components.The size of these glitches is quantied as the fractional change...
Pulsar glitches—sudden and discrete jumps in the rotational frequency of neutron stars—are important observational tools for studying matter at supranuclear densities. In this work, we present an updated analysis of glitch mechanisms and their implications for understanding the internal structure of neutron stars. We focus on the dynamics of vortex unpinning in the superfluid interior and the...
Intensity mapping for the 21 cm line is a promising route to map large-scale structure, but the cosmological HI signal is buried beneath Galactic and extragalactic foregrounds orders of magnitude brighter. We implement the Generalized Needlet Internal Linear Combination (GNILC) method to clean foregrounds from simulated MeerKAT single-dish observations in the UHF band (z ≈ 0.4–1.4)....
Atmospheric turbulence (seeing) degrades the quality of ground based astronomical observations by blurring stellar images. This study presents the first measurement of astronomical seeing at the Ileret observatory in Kenya to assess its suitability for optical observations. R-band observations of variable stars BV Aqr and RX Eri taken at Ileret during September 2024 and January 2025 were...
Bent-tail radio galaxies (BTRGs) are a subclass of radio-loud active galactic nuclei (AGN) characterised by their distinctive curved radio lobes. They are mostly found in dense environments, which raises a question of how environmental effects such as ram pressure influence the peculiar morphology that they exhibit. It is also not clear whether their AGN duty cycle, which is the ratio of the...
Developing affordable and scalable radio astronomy systems is essential for expanding research capacity in countries with emerging scientific infrastructure. A low-cost Software Defined Radio (SDR)–enhanced Radio JOVE telescope offers a practical pathway for strengthening radio astronomy capability in Nigeria through hands-on Jovian decametric (DAM) observations. This work presents the...
Abstract
Flaring activity is traditionally associated with stars possessing convective envelopes and strong magnetic dynamos. Normal A-type stars, characterized by purely radiative envelopes, are therefore expected to be magnetically inactive. However, recent surveys have reported flare-like events in several normal A-type stars, challenging current models of stellar magnetism. This project...
Radio interferometry techniques have been significantly improved in recent years with the construction of more sensitive radio telescopes such as MeerKAT and the future Square Kilometre Array (SKA), but the radio frequency interference (RFI) remains one of the main challenges limiting the sensitivity and calibration process. Harmonic RFI are produced by non-linearities in electronic equipment...
Abstract : Modern astronomy demands ever increasing performance from its instrument
A major obstacle for ground-based observations is the micro-fluctuations of temperature in the atmosphere which, modifying the refractive index of the air, randomly scramble the propagation of optical waves and cause a loss of information. The choice of a site for a future observatory is crucial for the...
This project dealt with restricting the birth rate of stars in post-starburst galaxies. Post-starburst galaxies are transitioning between young and old galaxies. They have different markers for identifying recent starburst like balmer absorption and nebular emmissions. Here we used Type II supernovae because they result from relatively young stars. This was important in further refining the...
We investigate whether radio emission primarily traces star formation in radio-quiet active galactic nuclei (RQ AGN). Our sample consists of 5223 galaxies detected by the MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE) survey with multi-wavelength counterparts up to a z ≈ 6 limit. The radio sources were classified using the infrared-to-radio luminosity ratio (q$_{\rm...
Active galactic nuclei (AGNi) are compact regions that emit throughout the electromagnetic spectrum. Blazars, a subclass of AGNi with their relativistic jets closely aligned with our line-of-sight, are especially powerful sources of $\gamma$-rays. Furthermore, the unified scheme for radio-loud AGNi classifies radio galaxies as the misaligned parent population of blazars. This would make them...
The quest for dark matter detection remains one of modern physics' greatest challenges, with indirect methods gaining prominence.
While gamma-ray observations have led the way in searches for Weakly Interacting Massive Particles (WIMPs), radio astronomy opens exciting new possibilities for detecting their annihilation or decay signatures.
The Local Group dwarf galaxies are pristine...
The Transient Array Radio Telescope (TART) is a low-cost, 24-element aperture synthesis array that continuously scans the sky for transient events. It also serves as a test bench for calibration, imaging algorithms, and hardware development for larger radio telescopes, like the MeerKAT and VLA telescopes. Now installed in several countries, TART is driving meaningful growth in radio astronomy...
Radio interferometry plays a critical role in modern astronomy, enabling high-resolution observations of celestial sources by combining signals from multiple antennas. The performance of any radio system—such as cellular networks, radar, radio telescopes, and interferometry systems—is significantly influenced by the sensitivity of the RF front-end receiver. Therefore, receiver efficiency is...
Context: The Perseus cluster (Abell 426) is the brightest cool-core galaxy cluster and hosts a complex mix of AGN-inflated bubbles, mini-halo emission, and weak shocks. Unlike classical merging clusters, Perseus shows low X-ray Mach numbers ($\mathcal{M}\sim1.2$--$1.6$), raising questions about how particles are accelerated in a non-merging environment where standard Diffusive Shock...
The Dogons of Mali have a long cultural history in interpreting and classifying celestial phenomena such as the stars Sirius A and Sirius B, reflecting human’s everlasting curiosity with the cosmos. Historically, surveys depended massively on human effort for classification which led to citizen-science projects like Zooniverse when early automated methods were unable to capture the subtle...
The Hydrogen Real-time Analysis eXperiment (HIRAX) is a radio interferometer array built with the purpose of measuring the Hydrogen Intensity (H1) power spectrum. It will eventually consist of 1024 6m dishes and will operate in the frequency range of 400-800MHz. In order for HIRAX to achieve its goal of measuring the Baryon Acoustic Oscillations (BAOs) in the power spectrum of neutral...
Investigating molecular clouds in External galaxies provides a valuable opportunity to explore how the distribution and dynamical state of star-forming regions are shaped by their galactic environment. This study investigates the dust properties of molecular clouds in Triangulum galaxy (M33) with a special focus on two giant molecular clouds (NGC 604 and GMC 16), using a calibrated data source...
Magnetohydrodynamics waves and instabilities in rotating, self-gravitating, anisotropic and collision-less plasma were investigated. The general dispersion relation was obtained using standard mode analysis by constructing the linearized set of equations. The wave mode solutions and stability properties of the dispersion relations are discussed in the propagations transverse and parallel to...
This project will study some of the auxiliary detections made in MeerKAT observations to constrain proto-galaxy-clusters. The observations are estimated to constitute more than 5000 radio sources in each of the three fields that were observed. This work will identify and conduct an analysis of the Elongated Radio Galaxies detected in these MeerKAT galaxy proto-clusters. Elongated Radio...
This study aims to validate the initial performance of the Single Star SCIDAR (SSS) instrument recently deployed at the Oukaimeden Observatory in Morocco. The primary objectives are twofold: (i) to assess its capability to retrieve real-time vertical profiles of the refractive index structure constant, Cn2(h), up to an altitude of 22 km, and (ii) to establish the reliability of the SSS system...
Fast rotating massive pulsators in eclipsing binaries are ideal candidates for studying interior mixing and angular momentum transport in massive stars. Different mixing processes such as convective overshooting, which transports only matter, and convective penetration, which transports both matter and heat, occur at the boundary between the convective and the radiative layers in a massive...
Radio galaxies, which emit significant radio-frequency radiation from their active cores, serve as powerful probes of supermassive black hole activity, galaxy evolution, and the physical conditions of their surrounding environments. The Africa Millimetre Telescope (AMT), which is upcoming and to be constructed in the Khomas Highlands of Namibia, will join the global Event Horizon Telescope...
- In this study, we investigate the evolution of the parameter
distribution of Post-Common Envelope Binaries. We focus on
understanding the gravitational timescale variations concerning
changes in orbital period and semi-major axis. Additionally, we
analyze the relationship between changes in orbital period and
alterations in the semi-major axis. Furthermore, we compare ...
Bars represent a common structural feature in disc galaxies, yet their contribution to galaxy evolution remains only partially understood. In this work, we examine how the presence of a bar influences the environmental dependence of various properties of disc galaxies. Our analysis uses a volume-limited sample from the Mapping Nearby Galaxies at APO (MaNGA) survey. Barred and unbarred disc...
Abstract
The Square Kilometre Array, the world largest radio telescope on Earth, is being built in South Africa and Australia, with the mid and low frequency arrays of this telescope being built in these respective countries. South Africa has already built the precursor instrument called MeerKAT, in preparation for this, offering unprecedented sensitivity and resolution at the L-band...
The formation and evolution of the Universe’s large-scale structure (LSS) are strongly influenced by the statistical properties of primordial density fluctuations. While cosmological hydrodynamical simulations, such as Simba-C, have become indispensable tools for modeling galaxy formation and cosmic web morphology, they generally adopt a fixed concordance $\Lambda$CDM initial power spectrum....
The 21 cm transition from neutral hydrogen is one of the most promising probes of the Epoch of Reionization (EoR). Precise measurements from this era can better constrain cosmological parameters, shedding light on the evolution of galaxies across cosmic time. The new generation of low-frequency radio interferometric arrays, including the Hydrogen Epoch of Reionization Array (HERA), have been...
We explore the three-dimensional structure of the Milky Way by tracing neutral atomic hydrogen (H I) using MeerKAT Absorption Line Survey (MALS) data. We aim to map the Galaxy’s spiral arms and large-scale features both along the midplane and at higher Galactic latitudes. Employing a Bayesian framework, consistent with Reid et al. (2016), we infer robust distance estimates to HI clouds from...
Understanding how magnetic activity drives ultraviolet (UV) irradiance variability is important for the advancement of space weather forecasting and modeling. In this study, we explore the dynamic relationship between solar magnetic flux density (MFD) and 133.5nm UV irradiance , with solar activity proxies ( f10.7cm radio flux, Mg II index, and Ca II K-line) during the ascending phase of Solar...
In this work, we explore the overlap between the MeerKAT Galaxy Cluster Legacy Survey (MGCLS), James Webb Space Telescope (JWST) observations, and the Galaxy Clusters at Vircam (GCAV) survey. This enables a detailed study of the radio galaxy population, extending down to the transition regime between AGN and starburst in elliptical galaxies, as well as to very faint star formation emission in...
Abstract
Gravitational lensing has become one of the most powerful probes of both astrophysics and cosmology,providing insights into dark matter, cosmic structure formation, and the accelerated expansion of the6 Universe. While the deflection of light by matter is well established within General Relativity, the role of the cosmological constant (Λ) in lensing remains debated (M. Ishak & W....
Asymmetries in a galaxy's neutral atomic hydrogen (HI) distribution and kinematics are key physical indicators of ongoing gas accretion or removal, which drives galaxy evolution. However, current classification methods - both parametric (e.g tilted-ring models) and non-parametric (e.g Asymmetry indices) often fail to reliably identify morphologically disturbed galaxies. Given the sheer number...
We present an intermediate–resolution 1.5 GHz study of the Lockman Hole using Cycle 16 e-MERLIN observations at $\sim200$ milliarcseconds (mas). The aim of this work is to make progress in identifying compact AGN activity in a field that has been extensively observed at low frequencies. The Lockman Hole was recently imaged with the International LOFAR Telescope (ILT) at 150 MHz with $\sim300$...
In an ongoing study we interpret the curved spectrum of the Vela pulsar as seen by H.E.S.S. II (up to ~100 GeV) and the Fermi Large Area Telescope to be the result of synchro-curvature radiation due to the acceleration of primary particles in a dissipative magnetosphere, within an extended separatrix region that leads into the current-sheet outside the light cylinder. We investigate the...
We present the first homogeneous photometric and spectroscopic study of four bright field stars (HD 73135, BD+190 2045, BD+190 2046, and TYC 1395-855-1) that lie in the immediate vicinity of the variable HD 73045. These were monitored, but never fully analysed, by the long-running Nainital-Cape Survey. Johnson-BV CCD time-series from four 0.4-1.3 m telescopes show all these stars to be...
The extended neutral hydrogen (HI) environments of spiral galaxies provide essential insights into galactic evolution but remain poorly characterised beyond optical boundaries. While star-forming regions define the visible galaxy extent, neutral hydrogen can extend far beyond as diffuse halos, tidal streams, and undetected gas-rich companions that significantly contribute to the total baryonic...
Hubble tension remains a major problem in modern cosmology due to the fact that it challenges $\Lambda$CDM model. The solution to this puzzle has been found to revolve around dynamical dark energy and interacting dark sector. K-essence is one of the numerous dark energy models first developed to explain inflation, then the accelerated expansion of the Universe. Unlike $\Lambda$CDM, k-essence...
In 2017 at the Maser conference (IAU symposium 287) in Cagliari in Italy, several results were shown, in particular two results, one from single-dish monitoring and the other from ALMA, of the same source. This showed the importance of collaborative work, and right there the Maser Monitoring Organization was found. The M20 consists of 11/12 single-dish observatories that monitors Masers, and...
In 2003 the methanol maser source G009.62+0.20E was the first source discovered to show periodic variability, together with six other sources. To present, more than 30 methanol masers have been found to show periodic variability, with several different flare profiles amongst them. However, G009.62+0.20E have been extensively studied in the past, with several competing theories trying to...
We study the observational signature of non-gravitational interaction between the dark components of the cosmic fluids. We explore a phenomenological models of interacting dark energy and dark matter, characterised by a linear and non-linear coupling term Q. These form of interactions naturally interpolates between linear regimes at early and late times, while avoiding divergences in the...
Magnetar giant flares (MGFs) and short gamma-ray bursts (SGRBs) are short gamma-ray transients (SGRTs) with overlapping temporal and spectral characteristics, making them challenging to distinguish, especially when their redshift is unknown. In this study, we apply supervised machine learning using a Support Vector Machine to classify MGFs and SGRBs. Temporal parameters (including pulse rise...
Understanding the star formation processes in galaxies is fundamental to unravelling the mysteries of galaxy evolution. This research focuses on evaluating the accuracy and correlation of three generally used star formation rate (SFR) indicators, which are the ultraviolet (UV) emission, far-infrared emission, and 1.4 GHz non-thermal radio continuum. From the Herschel Astrophysical Terahertz...
In the past two decades, a link between giant radio haloes and their host clusters’ dynamical state was established, with radio haloes detected in merging systems. It is not clear at which stage of the merger the cluster emits these synchrotron radio emissions. Our main aim is to investigate the dynamical states of galaxy clusters detected to host diffuse radio emission (haloes, relics, etc.)....
This research proposal investigates the impact of Botswana’s indigenous satellite, BOTSAT-1, on enhancing the operational capabilities of the Botswana Defence Force Air Arm Command (BDF AAC). Recognising the growing strategic importance of space technology in military operations globally, the study focuses on how BOTSAT-1’s hyperspectral imaging payload can be systematically integrated into...
In the mid-1970s, a periodic signal with a 160-min interval was detected from
the Sun, which the discoverers interpreted as a gravity mode (g-mode) oscillation,
suggesting it represented vibrations of the Solar surface. Similar signals were
also observed in various extraterrestrial sources, including Active Galactic Nuclei
(AGN). However, later analyses dismissed this signal as merely an...
The quiet Sun represents the majority of the solar surface outside of sunspots, pores, and plages, containing weak and dynamic magnetic fields whose origins are strongly linked to convective plasma motions. The study investigates the strength and configuration of vector magnetic fields in the quiet photosphere using spectropolarimetric observations from the Solar Optical Telescope (SOT-SP)...
Anekwe, Frances Ngozika1, Prof. James O. Chibueze2, Prof. A.E. Chukwude3, and Dr. Saul Paul Phiri4.
Department of Physics, School of Mathematics and Natural Sciences, Copperbelt University,Riverside,Zambia1,4,
UNISA Centre for Astrophysics & Space Sciences (U-CASS), Florida Campus, South Africa2,
Department of Physics and Astronomy, UNN, Enugu, Nigeria1,...
X-shaped radio galaxies (XRGs) are those radio jetted sources where the two jets bend in opposite directions, forming inversion symmetric structure. Despite the discovery of such sources in wide surveys, the detected fraction of these sources among radio-loud AGNs remains low. Recent studies using modern radio telescopes with improved sensitivity and resolution have revealed that candidate...
We present an analysis of the compact HII-region (G012.883–00.285) using VLA L-band continuum imaging from 1996 and MeerKAT L-band observations from 2018, providing a 22-year interferometric baseline. A systemic velocity of VLSR=35.705±0.092km/s, derived from C18O emission was used as input to a Bayesian parallax–kinematic model, which favours two high probability distance solutions:...
Archival data from wide-field surveys offer a rich, often untapped resource for the study of Solar System Objects (SSOs). The rapid growth of institutional archives has produced an outstanding volume of photometric data on asteroids and comets, creating unprecedented opportunities for scientific studies. Using archival data from the Isaac Newton Telescope Wide Field Camera, we present...
Active galactic nuclei (AGN) are some of the brightest sources in the Universe, emitting light at all wavelengths due to their complex structure. Deep multi-wavelength extragalactic surveys are therefore important for understanding the full physics of AGN and their role in the formation and evolution of galaxies. The Lockman-SpReSO survey is one of the deepest multi-wavelength spectroscopic...
The Transient Array Radio Telescope (TART) project represents an innovative approach to low-cost, open-source radio astronomy, developed by an international collective of volunteers to enable educational radio astronomy interferometry. Operating at 1.575 GHz in the GPS L1 band, TART utilises 24 patch antennas in an aperture synthesis configuration, with installations currently operational in...
Context: Abell2146 is a merging galaxy cluster with two shock fronts: a bow shock in front of the subcluster A2146-A and a slower upstream shock behind the main cluster A2146-B (Rusell et al. 2010). Despite deep GMRT observations at 325 MHz and JVLA observations at 1.4 GHz suggesting the potential presence of a radio relic, its existence in the outskirts of the merging cluster Abell 2146...
We present radio observations of the source G327.1-1.1, a non-thermal composite supernova remnant (SNR). Observations have been performed at eight frequencies with MeerKAT’s L-band (856 – 1712 MHz) receivers. The data is part of the SARAO MeerKAT Galactic Plane Survey (SMGPS) radio continuum which covers 251o ≤ l ≤ 358o, 2o ≤ l ≤ 61o at |b| ≤ 1.5o. With this data we have been able to produce a...
We present HI data cubes for 30 galaxy clusters from the MeerKAT Galaxy Cluster Legacy Survey (MGCLS), including 9 X-ray-selected and 21 radio-selected clusters out to redshift z ∼ 0.1. These wide-field HI observations provide a valuable resource for studying the influence of environment on galaxy evolution. The data are hosted on Amazon Web Services (AWS) S3 and are accessible via a...
Supernovae explosions are among the most powerful and brightest events in the universe, marking the end of the star’s life. These events although having been studied widely in optical and x-ray windows, radio observations offer a unique opportunity especially when the event happens within a dense environment. The radio emissions detected are produced through the synchrotron radiation...
Understanding the physical and dynamical conditions of massive star-forming cores is essential for constraining how high-mass stars assemble their mass and shape their environments. G358.46−0.39 is a massive proto-cluster previously identified to host 4 cores (MM1a, MM1b, MM1c, and MM2), yet its internal gas structure, chemical complexity, and driving sources of outflow activity remain poorly...
STUDY OF WATER MASERS IN THE STARBURST GALAXY M82.
ABSTRACT
The starburst galaxy M82 (the Cigar Galaxy) is a prominent host of 22 GHz water (H2O) maser emission, located primarily within its central ~1 kpc bar. While these masers are critical tracers of stellar distances and galactic dynamics, previous arcsecond-resolution studies have failed to fully resolve their complex morphology and...
Radio Frequency Interference (RFI) poses critical challenges for radio astronomy,
particularly solar radio astronomy, corrupting observations of fundamental phenomena
like the quiet sun, solar radio bursts, solar flares, and coronal mass ejections. We
present a detection pipeline combining multi-domain feature engineering with
unsupervised machine learning to deal with unavailable labeled...
This work presents a detailed multi-wavelength analysis of Low Luminosity Gamma-Ray Bursts (LL GRBs) afterglows within the standard forward-shock synchrotron framework. Using representative observing frequencies spanning radio ($10^{9}$ Hz), UV ($10^{15}$ Hz), x-ray ($10^{18}$ Hz), and $\gamma$-ray ($10^{20}$ Hz), model light curves were computed and interpreted under physically motivated...
This poster summarizes the current progress of a project developing a supervised machine learning (ML) framework to decompose galaxy structures using multi-wavelength data. A dataset from the 50 Mpc Galaxy Catalog (50MGC) has been assembled, and standardized g, r, i, z data-cube FITS images have been downloaded and generated. A full preprocessing pipeline covering star removal, segmentation,...
Precision calibration is fundamental in radio astronomy, as the accurate conversion of instrumental signals into physical units underpins reliable measurements of celestial radio sources. Among the available calibration strategies, internal noise diodes provide a stable and repeatable reference for determining receiver gain, system temperature, and flux density scaling.
In this study, we...
This multiphase, ongoing study offers a data-driven theoretical analysis of the Earth flyby anomaly using the Azimuthally Symmetric Theory of Gravitation (ASTG). We create minute-resolved trajectories for seven flybys and calculate the asymptotic velocity change predicted by ASTG using high-resolution Horizons ephemerides combined with IERS Earth orientation characteristics. The possibility...
We study the properties of 56 massive (M$_{\rm{\star}}$ > 10$^{10}$ M$_{\odot}$) galaxies at $z<1$ that host AGN, detected via their broadband optical variability in the VST-COSMOS survey. VST-COSMOS provides a nearly-identical single visit depth ($r$ $\sim$ 24.6 mag) and temporal baseline (eleven years) as the forthcoming Legacy Survey of Space and Time (LSST), albeit in a much smaller 1...
Over the past decade, Ghana has emerged as a pivotal player in Africa’s evolving radio astronomy landscape. The conversion of a decommissioned 32-metre telecommunications antenna into the Ghana Radio Astronomy Observatory (GRAO) exemplifies a national strategy that blends infrastructure reuse, scientific capacity building, and grassroots outreach. As one of the first cohort of locally trained...
We report the discovery of periodic maser variability of an unusual pattern in the high-mass young stellar object G26.598─0.024. Methods. A ten-year monitoring of the 6.7 GHz methanol maser was carried out with the Torun 32 m radio telescope. The archival data collected so far were also used to characterize the target with high angular resolution and examine its infrared variability. We found...
The Square Kilometre Array (SKA) will transform radio astronomy, producing vast volumes of complex data that require advanced skills in calibration, imaging, and analysis. Preparing for SKA science, therefore, demands hands-on experience with sensitive, high-resolution observations on pathfinder instruments such as MeerKAT.
Dwarf galaxies will be one of the major focuses of SKA surveys, as...
Hyperspectral imaging (HSI) from satellites provides rich spectral information for monitoring vegetation over large areas. However, many satellite applications in agriculture are limited by the lack of labelled benchmark data and weak semantic links between spectra and plant health. We introduce PlantHyper, a large-scale captioned hyperspectral dataset derived from the German EnMAP satellite...
The dawn of the MeerKAT era and the approaching Square Kilometre Array (SKA) present unprecedented data challenges and opportunities for South African astronomy. To meet this demand, the ilifu cloud computing facility has been established as a critical, researcher-driven infrastructure. Operated by the Inter-University Institute for Data-Intensive Astronomy (IDIA), ilifu provides the...
The persistent discrepancies between early and late universe cosmological measurements of the Hubble parameter ($H_0$) and the matter clustering parameter ($S_8$) pose significant challenges to current physics. In this study, we take into account such discrepancies to solve through the modified theory of gravity known as $f(Q)$ gravity (a symmetric teleparallel) framework where gravity is...
The MeerKAT Exploration of Relics, Giant Halos and Extragalactic Radio Sources (MERGHERS) survey was designed to investigate diffuse radio emission associated with merger activity in massive galaxy clusters. The pilot survey comprised a 16-hour observation of 13 massive clusters and revealed strong evidence of ongoing or recent mergers in several systems. This was followed by the Tier 1...
My MSc project aims to determine the dynamical state of approximately 30 Sunyaev–Zel’dovich-selected galaxy clusters that are part of the MeerKAT Exploration of Relics, Giant Halos, and Extragalactic Radio Sources (MERGHERS) survey. Understanding the dynamical state of a cluster is essential for correctly characterising diffuse radio emission such as halos, relics, and mini-halos which is...
The South African Astronomical Observatory (NRF-SAAO) is now several years into the Intelligent Observatory (IO) initiative, a strategic program designed to modernise the observatory and its operations to meet the scientific demands of the astronomical community in the era of modern data-driven astronomy enabled by the Fourth Industrial Revolution. The IO project encompasses a broad suite of...
Exciton-polariton condensates, formed through strong light-matter coupling in semiconductor microcavities, have emerged as powerful laboratory platforms for exploring analogue gravity and nonlinear hydrodynamic phenomena. We investigate the instability-driven dynamics of topologically charged solitons in driven–dissipative spinor polariton condensates, modelled with a two-component...
Protoplanetary disks (PPDs) are dominated by molecular $H_{2}$ and $He$, with minor species serving as essential tracers of the disk structure and evolution. Rich ALMA-based evidence strongly suggests that different gaseous species in the disk are vertically stratified. However, the classical thermal scale height $H_\text{therm} = c_s/\Omega$ is fundamentally limited in explaining this...
Gamma-ray binaries are a rare subclass of high-mass systems in which a neutron star or black hole orbits an O- or B-type companion, producing broadband non-thermal emission that peaks in the γ-ray regime. This study investigates the particle populations responsible for the observed emission in the γ-ray binaries 1FGL J1018.6−5856 and LMC P3. Using phase-resolved 2019 MeerKAT L-band...
Julius Chuhwak Matthew*1,2; Roberto De Propris1,3; Jorge Melnick4; Susan E. Ridgway5
1Department of Physics and Astronomy, Botswana International University of Science and Technology (BIUST), Private Bag 16, Botswana
2Department of Physics and Astronomy, University of Nigeria Nsukka (UNN); julius.matthew.93565@unn.edu.ng
3Finnish Centre for Astronomy with ESO, University of Turku,...
We present a theoretical study of charged, non-rotating black holes
(Reissner–Nordström black holes) in the Marongwe space-time. The solution is obtained by solving the Marongwe Nexus paradigm equations within the semiclassical regime. These equations represent a modified form of Einstein’s field equations (EFEs). Our findings indicate that, in the ground state, the spacetime metric closely...
In this talk, I will present our analysis of the dark matter halos of nearby LADUMA galaxies, using high-quality HI rotation curves combined with multi-band photometry to separate the contributions of stars, gas, and dark matter to the total mass. By fitting different halo models—including NFW, pseudo-isothermal, and the more flexible generalized NFW profile—I will show how allowing the inner...
Context: Galaxies in the cluster environment differ from field or isolated galaxies, with ellipticals and lenticulars dominating in dense cluster environments and spirals in the field populations, hence, the morphology-density relation. Cluster galaxies tend to have older stellar population, suppressed star formation and are on average HI deficient compared to their field galaxies...
Fast Radio Bursts (FRBs) are millisecond-duration radio emissions originating from cosmological distances, as indicated by their large dispersion measures. Although numerous FRBs have now been localised to their host galaxies, a distinct class of compact electromagnetic counterpart, Persistent Radio Sources (PRSs), has also been identified in some cases. Currently, only four repeating FRBs...
The pulsating surfaces of stars, observed as minute oscillations in brightness due to its intrinsic behavior, provide a unique window into their otherwise hidden interiors. This field of asteroseismology allows us to effectively "see" stellar structure using the resonant sound waves acoustic p-modes that propagate within them. Driven by turbulent convection in the outer envelope, these waves...
The Hartebeesthoek Radio Astronomy Observatory operates long running single-dish continuum and spectroscopic programs that support astronomy and geodesy in Africa and globally. The continuum program provides multi wavelength flux density monitoring of compact sources for variability and calibration studies. The spectroscopic program tracks OH, H2O, and methanol masers in star-forming regions...
Low-frequency radio observations are revealing an increasing number of radio galaxies with unusual morphologies that reflect strong interactions between the jets and their surrounding medium. In this work, we present the first detailed study of the peculiar bent-tail radio galaxy MKAT J131855.02–184708.00, only the second known source to exhibit a pronounced “omega-shaped’’ structure. Our...
The Narrow-Line Seyfert 1 Galaxy (NLS1) AGN, J1522+3934 was observed to study core-jet evolution, which is the observation of jets growing as frequency progresses. Core-jet evolution is important as it generates better understanding of the physics of jets that influence star formation through AGN feedback. Imaging and spectral analysis were performed in the X (8-12 GHz) and K (18-27 GHz)...
Massive stars play a central role in shaping our Galaxy, but understanding how they form is still challenging. Their birth environments are deeply hidden inside dense clouds, they evolve quickly, and their strong feedback disrupts the surrounding gas. Millimetre spectral line observations offer a powerful way to study these early stages, revealing the physical and chemical conditions inside...
The results of spectral and photometric analyses of six chosen massive Herbig AeBe stars for the years 2023–2024 are presented in this research. Spectral investigations show that the emission spectra varies significantly across time intervals between one month and one year. The circumstellar disk's condition was described by an energy distribution curve. Two of the six stars are seen to have...
3I/ATLAS is the second known comet of extrasolar origin. It was discovered on 1 July 2025, and immediately attracted the attention of many observers. Studying its composition and evolution lets us probe the solid-body formation in other planetary systems. Using the DDT time at SALT we observed 3I/ATLAS with the RSS spectrograph on 15 and 29 July 2025. Both spectra were acquired in the...
Abstract
Supernova SN2008iz, discovered in the starburst galaxy M82, represents a rare opportunity to examine a massive stellar explosion occurring in a heavily dust-obscured region. Unlike typical supernovae detected in optical surveys, SN2008iz remained invisible due to extreme extinction, leading to its discovery and follow-up primarily at radio wavelengths. Such observations are critical...
Pulsar glitches—sudden increases in the rotational frequency of neutron stars—provide a probe of matter at densities exceeding nuclear density, but most pulsars glitch only once, limiting individual studies. Ensemble analyses show a bimodal glitch-size distribution, interpreted by some as evidence for two trigger mechanisms: small glitches (<10⁷) and large glitches (>10⁷). Others argue both...
We present a detailed study of the spider binary system PSR J1748-2446A in the globular cluster Terzan 5, utilizing high-resolution radio observations from the MeerTime project on the MeerKAT telescope. In this unique system, a millisecond pulsar (MSP) is in a tight orbit with a low-mass companion star, resulting in complex interactions and eclipsing phenomena. Notably, the pulsar’s intense...
We present a study of protocluster subsample IRAS 16445-4459 using high-resolution ALMA band 6 (λ ~ 1.3 mm) QUARKS survey selected for UC H II regions traced by the H30α Radio recombination line (RRL) and meerKAT 1.3 GHz observation G340.248-00.046 to investigate the excitation mechanism of the H30α RRL in the high-mass forming region. The source reveals the detection of the RRL indicating...
The history of the expansion of the universe encodes critical information about its composition and the underlying physics that governs cosmic evolution. In this work, we investigate the role that viscous cosmic fluids may play in setting the background dynamics of the universe within the FLRW framework. By extending the standard model of cosmology to include bulk viscosity in the cosmic...
The chemical abundance of active galaxies, which host active galactic nuclei (AGN) at their centre, remains poorly studied due to the difficulty of removing the effect of AGN in metallicity measurements. In particular, the chemical abundance of active galaxies in different environments, including clusters and groups, is still unknown. We use a novel HCm code (HII-CHI-mistry) adapted to measure...
Algol-type eclipsing binaries provide a unique laboratory for investigating the complex interactions that occur during star evolution, including mass transfer between components of near binary systems. In this study, we create and apply evolutionary computational models to simulate mass transfer processes in such systems, with an emphasis on conservative and non-conservative scenarios. By...
The investigation of the effect of magnetic field interaction on the orbital path of binary stars is challenging in the field of stellar physics due to the dominance of stellar equilibrium. This study explores the effect of magnetic field interaction on the orbital pats of binary stars by analyzing radial velocity. Specific conditions are used to calculate the radial velocity of a binary star....
The presence of Active Galactic Nuclei (AGN) can significantly influence the morphological classification of galaxies, particularly at intermediate and high redshifts where observational limitations further complicate structural measurements. This study investigates how different levels of AGN contribution affect six widely used non-parametric morphological parameters under COSMOS-like...
We present a multi-wavelength study of $\sim150$ Brightest Cluster Galaxies (BCGs) spanning $0.3 < z < 0.8$, tracing the evolution of AGN feedback, star formation, and environmental dependence across $\sim3.4$~Gyr. Clusters are selected via the Sunyaev-Zel'dovich (SZ) effect, enabling robust mass estimates and a redshift-independent selection function. We combine radio data from ASKAP (RACS)...
While Dark Matter (DM) is treated as a single substance in contemporary astrophysics and cosmology research, the process whereby the DM paradigm has been established is a complex one, involving both theoretical contributions and astronomical observations. In defining this paradigm, we divide the DM epistemic terrain into an observational region, a theoretical region and an experimental region....
"The jets and extended lobes of extragalactic radio sources are known to play a key role in AGN feedback processes and the co-evolution of supermassive black holes and their host galaxies. However, although sufficient energy input is available from jets, both the regulation of feedback and the processes required to heat the intergalactic medium remain open questions. To resolve them, we need...
Collisional Ring Galaxies (CRGs) form when a small galaxy companion passes through the larger disk galaxy in its central region, creating a radial density wave that compresses the gas and triggers intense star formation (SF) across a bright structured ring. Although rare, these systems provide a suitable environment to study interaction-induced SF processes and to constrain galactic evolution...
We use quasars in nearby surveys to study their environmental and stellar population properties in comparison with inactive galaxies in the same volume
Our findings show that quasars in the nearby universe do not generally favor different environments from those of normal galaxies. Quasars are hosted preferentially in star forming galaxies, mainly Sa and Sb and are less frequent in...
A supernova is a powerful stellar explosion that mars the death of a star. It occurs when a star can no longer sustain the forces that keep it stable, resulting in a sudden collapse or a thermonuclear runaway, releasing enormous amounts of energy within seconds. These events are categorized mainly as thermonuclear or core-collapse types. After the explosion, the expelled stellar material...
Very Long Baseline Interferometry (VLBI) plays a crucial role in resolving radio sources which are typically unresolved in large
area surveys, but tend to have variety of morphologies that include FR-II like radio sources. Such sources could be at an early stage of their evolution or alternatively, they may be at the end of their life-cycle and are small due to being frustrated by the host...
Meteoroids, as fragments of small Solar System bodies altered by collisions, rotation, and thermal processes, impact the Earth’s on a daily basis. Upon their atmospheric entry, they produce light, ionization, and shock waves detectable across multiple sensors.
Over the past two decades, wide-field optical networks (e.g., video/fireball arrays), infrasound and seismic arrays, and space-based...
ABSTRACT
Hydra A is a FR-I type radio galaxy located at the centre of the Abell 780 cluster with a redshift of $ z = 0.054$. Previous observations of the radio galaxy have been conducted at low frequencies by the Very Large Array (VLA) telescope and using the L-band frequencies of the MeerKAT array telescope. The Chandra X-ray observatory also carried out a detailed survey of the X-ray...
The analysis of stellar surface oscillations provides a unique window into stellar interiors, enabling precise determination of fundamental properties of solar-type stars, such as radius, mass, and age. Among these properties, age estimation is particularly crucial, serving as a cornerstone for understanding galactic dynamics by offering insights into the timescales of star formation and...
C/2017 K2 (PanSTARRS), hereafter K2, is a dynamically new comet, discovered by the Pan-STARRS survey in May 2017, when it was at a heliocentric distance of rh=16.1 au. Further investigations enabled to find a pre-discovery images of comet K2 exhibiting activity at a very large distance of 23.8 au in May 2013. K2 is the second most distant active comet ever discovered, with CO detected in...