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...
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...
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...
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...
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...
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...
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...
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...
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....
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. 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 model, k-essence is an effective scalar...
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...
Low Noise Amplifiers are devices suitable for detecting and amplifying low power radio signals without changing the electromagnetic properties of the signals. In order to achieve this, design requirements are such that these devices must be characterized by high performance parameters such ultra-low noise figures, high gain, high dynamic range, high sensitivity and stability in order to...
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...
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 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...
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....
Brightest cluster galaxies (BCGs) host powerful active galactic nuclei (AGN) that regulate the heating–cooling balance of the intracluster medium. We study AGN activity in 171 BCGs in Sunyaev–Zel’dovich selected clusters from the AdvACT survey over 0.3 < z < 0.8 using SALT spectroscopy, WISE mid-infrared photometry, ASKAP RACS radio data, and X-CIGALE SED modelling. We find that 26% of BCGs...
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...
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...
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...
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...
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...
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...
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...
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...
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 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...
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...
The Square Kilometre Array (SKA) will transform radio astronomy by enabling the detection of large populations of faint, low-mass dwarf galaxies that are currently beyond the reach of existing facilities. As the most numerous galaxy population and highly sensitive to feedback and environmental processes, dwarf galaxies provide key laboratories for studying galaxy formation and evolution...
Bent-tail radio galaxies provide important insights into the interaction between radio jets and their surrounding environments. 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 exhibiting a pronounced omega-shaped jet morphology. Using the high sensitivity of MeerKAT observations, we resolve the...
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)...
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...
"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...
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...
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)...
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...
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...
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...
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...
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...
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 $\sim300$...
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 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...
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,...
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...
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,...
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...
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...
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...
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 rapid expansion of Low Earth Orbit (LEO) satellite constellations presents a new frontier for high-resolution Earth Observation, yet existing systems remain largely uncoordinated and incapable of producing unified, near-real-time mosaic images. Unlike geostationary satellites, LEO satellites operate at approximately 500 km altitude, move rapidly across the Earth’s surface, and possess...
Astrotourism offers an opportunity for Zambia to diversify its tourism sector and strengthen its position within the regional science, adventure and cultural tourism market. In this project we carried out an objective geographical survey to identify the best locations to develop the astrotourism industry. We considered the following aspects in our spatial analysis: light pollution(VIIRS data),...
Career Dreams Centre, a pioneering tourism and hospitality training institution in Botswana, has been operating for over nineteen years and stands among the first schools in the country to offer professional safari guiding programmes. From its early inception, the Centre integrated a foundational astronomy module into its safari guiding curriculum, emphasizing understanding celestial...
Girls’ education and STEM participation in Zambia face persistent structural, socio-cultural, and institutional barriers. Although gender parity exists at the primary level (1.03), girls’ representation declines at secondary school (0.94 in 2020), with completion rates as low as 26.5–26.7% in some provinces. High teenage pregnancy, 27.6% nationally, reaching 36.2% in rural areas and 43% in...
Abstract:
Astrophotography is a powerful bridge between science, creativity, and public engagement. In Liberia, the Liberian Astronomical Society (LAS) uses this tool to promote astronomy education and inspire curiosity among students and communities. By capturing images of the Moon, planets, star clusters, and other celestial objects, astrophotography makes astronomy visually accessible to...
Ethiopia's emerging amateur astronomy movement faces significant infrastructural and logistical barriers that impede its transformation into a robust observational network. The Ethiopian Space Science Society (ESSS) serves as the key organizational catalyst, focusing specifically on supporting and enabling high-level amateur activities and addressing systemic challenges within the community....
This research explores effective strategies for delivering astronomy education that fosters student engagement and promotes early career development in science. As a young university lecturer in physics and astronomy, I've observed the challenges students face in keeping engaged with scientific content. This study aims to identify and implement innovative pedagogical approaches that make...
NASA's Astronomy Picture of the Day (APOD: apod.nasa.gov) has been featuring and explaining astronomical images from around the world for over 30 years, including many from Africa. This presentation will feature images on APOD that originated from countries in Africa including Algeria, Botswana, Canary Islands (Spain), Chad, Congo, Egypt, Ethiopia, Gabon, Kenya, Libya, Mauritania, Morocco,...
Felek, named after the Ge’ez word for “planet,” is a bold digital learning platform developed by the Ethiopian Space Science Society (ESSS) to redefine how space science is accessed and understood in Ethiopia. The platform represents a major step toward bridging long-standing gaps in space education across the country. For many years, space science has not been included in elementary or high...
Astronomy and space science in Africa are evolving beyond traditional research fields into powerful catalysts for innovation, public engagement, and national development. However, their full societal potential remains largely untapped, especially in advancing STEM literacy, digital transformation, and public health resilience. This project introduces an interdisciplinary framework integrating...
In Nigeria, where opportunities for astronomy education have historically been limited, the "Asthera" Astronomy outreach program is fostering meaningful development by inspiring scientific curiosity, creative learning, and a sense of wonder among young scientists. Through these outreaches children/students are introduced to the fundamentals of Space science through interactive activities such...
The 1.07 Ma Bosumtwi impact crater in Ghana is one of the best-preserved large impact structures on Earth. It is the source crater of tektites, glassy distal ejecta that are found in the region of Daoukro (Côte d’Ivoire) as well as offshore West Africa in deep sea sediments. All these unique features, together with the lake sediments recording the climate of the past million years, led to a...
The Africa Millimetre Telescope (AMT) program successfully facilitates a mobile planetarium in Namibia as part of its educational and outreach projects. The idea for the project arose in the early stages of exploring the possibility of building the telescope in Namibia. However, the lack of locally qualified and experienced technical and scientific personnel to run the operations phase became...
Public stargazing has become a transformative approach to expanding astronomy awareness and scientific curiosity among Ethiopian communities. While formal astronomy education remains limited in many parts of the country, especially in regions without access to laboratories or science clubs, public observing nights offer an open and inclusive platform where individuals of all ages can directly...
This work aims to choose potential astronomical sites that can be candidates for a new astronomical optical observatory in Ethiopia in addition to the Entoto Observatory and Lalibela sites. For our primary investigation, the six basic criteria, namely the altitude of the mountains, artificial light pollution, cloud coverage, humidity, wind speed, and wind direction, were taken into account. ...
Radio continuum emission at 1.4\,GHz is widely used as a tracer of star formation rate (SFR) in radio-based galaxy evolution studies. However, the standard relation is highly uncertain, due to complications such as active galactic nucleus (AGN) contamination, synchrotron suppression, and high intrinsic scatter. Thus we investigate the use of a machine learning framework trained on WISE-based...
Space Science & Astronomy aspects have been recently included in Ugandas Secondary School Curriculum. The Curriculum has also been improved to entail a Competency Based Teaching style of teaching. The inclusion of aspects of space science and astronomy has called for the need to re-tool physics teachers; especially those that did not have their training at Universities with Astronomy and space...
Science Explorer (SciX) is a cross-disciplinary discovery platform and outreach program that connects literature, data, and software across astronomy, planetary science, heliophysics, and related fields. The platform is developed under a NASA collaboration, and supports open-science through linking between research, advanced search (including similarity and trend exploration), visual analytics...
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...
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...
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....
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
Ethiopia is currently experiencing significant political, economic, and educational challenges that have weakened the quality of schooling and limited opportunities for young learners. In this context, astronomy outreach has emerged as a meaningful tool to restore hope, spark curiosity, and strengthen STEM engagement—especially for students with minimal access to scientific resources. This...
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...
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...
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 rapid variability. This study aims to investigate the fine-scale...
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...
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...
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....
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...
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...
- 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 ...
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...
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...
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.)....
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...
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,...
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:...
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...
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...
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 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...
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...
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...
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...
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 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...
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...
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...
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...
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...
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...
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...
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...
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)...
We present a systematic investigation of filamentary synchrotron structures in radio galaxies, using deep 144 MHz observations from the \textit{LOFAR} Two-Metre Sky Survey (LoTSS) in combination with archival \textit{ROSAT} X-ray data. These narrow, collimated features - linking radio lobes and often aligned with jet axes -are rare, with (\sim2.2\%) of radio galaxies exhibiting such...
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...
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 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...
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 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....
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...
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...
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...
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...
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...