Research Article
Variation of Total Electron Content over May 10 - 13 2024 Geomagnetic Super Storm in South Africa
Efrem Amanuel Data*
Issue:
Volume 13, Issue 2, June 2025
Pages:
21-35
Received:
4 March 2025
Accepted:
27 March 2025
Published:
11 April 2025
Abstract: This study investigates the variation of Total Electron Content (TEC) over South Africa during the geomagnetic superstorm of May 10 - 13, 2024. This study aims to analyze the variation of TEC over South Africa during the May 10 - 13, 2024, geomagnetic superstorm using data from the IRI-2020 model, GNSS-based TEC measurements, and other geomagnetic parameters. The root mean square error (RMSE) method was applied to quantify the deviations between GPS-derived TEC measurements and the IRI-2020 model during the geomagnetic storm. The results reveal significant TEC fluctuations, with a pronounced increase during the main phase due to prompt penetration electric fields (PPEFs) and storm-induced ionospheric disturbances. This was followed by a sharp TEC depletion in the recovery phase, attributed to thermospheric composition changes, particularly oxygen-to-nitrogen ratio variations. Magnetometer H-component observations further confirm the strong geomagnetic activity associated with the storm, indicating enhanced ionospheric currents and electrodynamic coupling. Latitudinal variations in TEC revealed complex ionospheric dynamics, with more pronounced disturbances at mid-latitudes. The ionospheric irregularities affected GNSS-based positioning, highlighting the impact of geomagnetic storms on navigation systems. These findings provide valuable insights into ionospheric storm effects over South Africa, contributing to improved space weather forecasting, GNSS accuracy, and regional ionospheric modeling.
Abstract: This study investigates the variation of Total Electron Content (TEC) over South Africa during the geomagnetic superstorm of May 10 - 13, 2024. This study aims to analyze the variation of TEC over South Africa during the May 10 - 13, 2024, geomagnetic superstorm using data from the IRI-2020 model, GNSS-based TEC measurements, and other geomagnetic ...
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Research Article
The Interplay Between Supermassive Black Holes and Their Host Galaxies: A Multi-wavelength Approach
Diriba Gonfa Tolasa*
Issue:
Volume 13, Issue 2, June 2025
Pages:
36-48
Received:
12 March 2025
Accepted:
31 March 2025
Published:
22 April 2025
Abstract: The interplay between supermassive black holes (SMBHs) and their host galaxies is a critical area of research in extragalactic astronomy, shedding light on the fundamental processes that govern galaxy formation and evolution. This study employs a multi-wavelength approach to investigate the correlation between SMBHs and their host galaxies, utilizing data from radio, optical, infrared, and X-ray observations. Recent advancements in observational technologies have enabled deeper insights into the mechanisms at play in this complex relationship. We begin by examining the fundamental connection between the mass of SMBHs and various properties of their host galaxies, such as stellar mass, bulge structure, and star formation rate. Our analysis reveals a significant correlation between SMBH mass and the central velocity dispersion of stars, consistent with the established M-sigma relation. However, deviations from this correlation suggest the influence of additional factors, such as environmental conditions and galaxy mergers. Furthermore, we explore the feedback mechanisms initiated by SMBHs, particularly through active galactic nuclei (AGN) activity. Multi-wavelength observations allow us to assess the impact of AGN feedback on star formation within host galaxies. We document cases where AGN activity suppresses star formation, resulting in a transition from star-forming to passive galaxies. Conversely, we also identify scenarios where SMBH feedback may trigger star formation, underscoring the dual role of SMBHs in galaxy evolution. In addition to examining individual cases, we utilize large galaxy survey data sets to analyze trends across different galaxy populations. Our findings indicate variations in SMBH-host galaxy relationships based on galaxy morphology and environment, suggesting that the evolution of both components is influenced by cosmic structures. This study highlights the importance of a multi-wavelength approach in understanding the complex dynamics between SMBHs and their host galaxies. By integrating diverse data sources, we provide a comprehensive view of how these colossal entities coexist and interact. Our results contribute to the broader discourse on galaxy formation theories and the role of SMBHs in shaping the universe, paving the way for future investigations that will deepen our understanding of cosmic evolution.
Abstract: The interplay between supermassive black holes (SMBHs) and their host galaxies is a critical area of research in extragalactic astronomy, shedding light on the fundamental processes that govern galaxy formation and evolution. This study employs a multi-wavelength approach to investigate the correlation between SMBHs and their host galaxies, utilizi...
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Research Article
Ionospheric Response to November 5-6, 2023 Geomagnetic Storm over West African Sector
Issue:
Volume 13, Issue 2, June 2025
Pages:
49-62
Received:
16 January 2025
Accepted:
22 April 2025
Published:
26 May 2025
DOI:
10.11648/j.ijass.20251302.13
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Abstract: This paper investigates the response of the ionosphere to November 5-6, 2023 geomagnetic storm in West African sectors. The November 5-6, 2023 geomagnetic storm, a significant space weather event, had profound effects on the ionosphere over the West African sector, particularly in countries such as Ghana, Senegal, Benin, Cabo Verde, and Cote d’Ivoire. To investigate the ionospheric response during this storm, the study focused on key parameters such as Total Electron Content (TEC), solar wind conditions, and the horizontal component of Earth’s magnetic field. Using data from GNSS/GPS stations, thermospheric neutral composition measurements, and satellite observations, the analysis reveals marked variations in TEC and other ionospheric parameters, indicating a strong ionospheric response. The analysis of TEC revealed marked variations during the storm, with significant positive ionospheric storm phases observed in countries such as ACRG; Ghana and YKR; Cote d’Ivorie, with TEC values on both November 5 and 6 are significantly higher than the quiet day mean, especially during the early afternoon hours (10:00 UT to 18:00 UT). In contrast, the TEC variations in DAKR; Senegal, CPVG; Cabo Verde and BJC; Benin were less pronounced, suggesting a weaker storm influence in these regions. The relative proximity of these stations to the geomagnetic equator might account for the observed differences, as the equatorial ionosphere is known to respond differently to geomagnetic disturbances compared to higher latitudes. The results highlight the complex interactions between solar wind, geomagnetic activity, and ionospheric conditions in the West African region, providing valuable insights for understanding and predicting ionospheric disturbances. The storm also had a noticeable effect on the thermospheric composition, as indicated by changes in the O/N2 ratio. The result suggests that the thermosphere experienced a slight relaxation in storm effects by November 6, but with some residual disturbances. Additionally, the prompt penetration electric field model, (PPEFM) effectively captured the behavior of the prompt penetration electric field, PPEF, which intensified or suppressed the prereversal enhancement (PRE) during the postsunset period in the main phase of the March 5-6, 2023, storms.
Abstract: This paper investigates the response of the ionosphere to November 5-6, 2023 geomagnetic storm in West African sectors. The November 5-6, 2023 geomagnetic storm, a significant space weather event, had profound effects on the ionosphere over the West African sector, particularly in countries such as Ghana, Senegal, Benin, Cabo Verde, and Cote d’Ivoi...
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