Research Articles: Recent submissions

Now showing items 41-60 of 95

    • Cosmological perturbations in f(G) gravity 

      Munyeshyaka, Albert; Ntahompagaze, Joseph; Mutabazi, Tom (International Journal of Modern Physics D, 2021)
      We explore cosmological perturbations in a modified Gauss-Bonnet f(G) gravity, using a 1+3 covariant formalism. In such a formalism, we define gradient variables to get perturbed linear evolution equations. We transform ...

    • Rotation and spots in normal A and Am/Fm stars 

      Trust, Otto; Jurua, Edward; Cat, Peter De; Joshi, Santosh (Monthly Notices of the Royal Astronomical Society, 2020)
      Frequency analysis of long-term ultraprecise photometry can lead to precise values of rotation frequencies of rotating stars with ‘hump and spike’ features in their periodograms. Using these features, we computed the ...

    • Are the observed gaps in protoplanetary discs caused by growing planets? 

      Ndugu, N; Bitsch, B; Jurua, E (Monthly Notices of the Royal Astronomical Society, 2019)
      Recent detailed observations of protoplanetary discs revealed a lot of substructures that are mostly ring like. One interpretation is that these rings are caused by growing planets. These potential planets are not yet ...

    • Tracking the Ionospheric Response to the Solar Eclipse of November 03, 2013 

      Amabayo, Emirant Bertillas; Anguma, Simon Katrini; Jurua, Edward (International Journal of Atmospheric Sciences, 2014)
      The ionospheric dynamics is highly influenced by the solar radiation. During a solar eclipse, the moon occults the solar radiation from reaching the ionosphere, which may drastically affect the variability of the ionosphere. ...

    • The role of density perturbation on planet formation by pebble accretion 

      Andama, G.; Ndugu, N.; Anguma, S. K.; Jurua, E. (Monthly Notices of the Royal Astronomical Society, 2022)
      Protoplanetary discs exhibit a diversity of gaps and rings of dust material, believed to be a manifestation of pressure maxima commonly associated with an ongoing planet formation and several other physical processes. ...

    • Statistical characterization of equatorial plasma bubbles over East Africa 

      Abiriga, Faustine; Amabayo, Emirant B.; Jurua, Edward; Cilliers, Pierre J. (Journal of Atmospheric and Solar-Terrestrial Physics, 2020)
      Bubble-like structures that grow in the post-sunset F-region of the equatorial ionosphere have continued to raise concern and research interest among scientists. These structures, commonly referred to as Equatorial Plasma ...

    • Probing the impact of varied migration and gas accretion rates for the formation of giant planets in the pebble accretion scenario 

      Ndugu, N; Bitsch, B; Morbidelli, A; Crida, A; Jurua, E (Monthly Notices of the Royal Astronomical Society, 2020)
      The final orbital position of growing planets is determined by their migration speed, which is essentially set by the planetary mass. Small mass planets migrate in type-I migration, while more massive planets migrate in ...

    • Statistical analysis of the correlation between the equatorial electrojet and the occurrence of the equatorial ionisation anomaly over the East African sector 

      Mungufeni, Patrick; Habarulema, John Bosco; Migoya-Orué, Yenca; Jurua, Edward (In Annales Geophysicae, 2018)
      This study presents statistical quantification of the correlation between the equatorial electrojet (EEJ) and the occurrence of the equatorial ionisation anomaly (EIA) over the East African sector. The data used were for ...

    • Investigation of the impact of Ionospheric Scintillation on GNSS Performance over East Africa 

      Abiriga, Faustine; Amabayo, Emirant B; Jurua, Edward; Cilliers, Pierre J (Advances in Space Research, 2021)
      In recent decades, the reliance on Global Navigation Satellite System (GNSS) applications is gaining ground in the East African region. This region lies within the low geomagnetic latitudes where signal scintillation events ...

    • Statistical analysis of TEC perturbations over a low latitude region during 2009–2013 ascending solar activity phase 

      Andima, Geoffrey; Jurua, Edward; Amabayo, Emirant Bertillas; Habarulema, John Bosco (Advances in Space Research, 2015)
      Total Electron Content (TEC) perturbations are manifestations of ionospheric irregularities which induce fluctuations in the amplitude and phase of trans-ionospheric radio signals. TEC data derived from Global Positioning ...

    • Simultaneous ground-based and in situ Swarm observations of equatorial F-region irregularities over Jicamarca 

      Aol, Sharon; Buchert, Stephan; Jurua, Edward; Milla, Marco (In Annales Geophysicae, 2020)
      Ionospheric irregularities are a common phenomenon in the low-latitude ionosphere. They can be seen in situ as depletions of plasma density, radar plasma plumes, or ionogram spread F by ionosondes. In this paper, we compared ...

    • Planetary core formation via multispecies pebble accretion 

      Andama, G; Ndugu, N; Anguma, S. K; Jurua, E (Monthly Notices of the Royal Astronomical Society, 2021)
      In the general classical picture of pebble-based core growth, planetary cores grow by accretion of single pebble species. The growing planet may reach the so-called pebble isolation mass, at which it induces a pressure ...

    • Hermes Spectroscopy of Normal A and Am Stars 

      Trust, Otto; Jurua, Edward; Cat, Peter De; Joshi, Santosh; Lampens, Patricia (Monthly Notices of the Royal Astronomical Society,, 2021)
      The nominal Kepler mission provided very high precision photometric data. Using these data, interesting phenomena such as spots, and ‘hump and spike’ features were observed in the light curves of some normal A and metallic ...

    • 1 + 3 covariant perturbations in power-law f(R) gravity 

      Murorunkwere, Beatrice; Ntahompagaze, Joseph; Jurua, Edward (The European Physical Journal C, 2021)
      We applied the 1+3 covariant approach around the Friedmann–Lemaître–Robertson–Walker (FLRW) background, together with the equivalence between f (R) gravity and scalar-tensor theory to study cosmological perturbations. We ...

    • A search for new γ-ray blazars from infrared selected candidates 

      Musiimenta, Blessing; Arsioli, Bruno Sversut; Jurua, Edward; Mutabazi, Tom (Proceedings of the International Astronomical Union, 2021)
      We present a systematic study of gamma-ray blazar candidates based on a sample of 40 objects taken from the WIBR catalogue. By using a likelihood analysis, 26 of the 40 sources showed significant gamma-ray signatures 3σ. ...

    • Perturbations in the interacting vacuum 

      Munyeshyaka, Albert; Ntahompagaze, Joseph; Mutabazi, Tom; Mbonye, Manasse.R; Ayirwanda, Abraham; Twagirayezu, Fidele; Abebe, Amare (arXiv, 2022)
      In this study, we present the evolution of cosmological perturbations in a universe consisting of standard matter and interacting vacuum. We use the 1 + 3 covariant formalisms in perturbation framework and consider two ...

    • Multi uid cosmology in f(G) gravity 

      Munyeshyaka, Albert; Ayirwanda, Abraham; Twagirayezu, Fidele; Murorunkwere, Beatrice; Ntahompagaze, Joseph (arXiv, 2022)
      The treatment of 1+3 covariant perturbations in a multiuid cosmology with the consideration of f (G) gravity, G being the Gauss-Bonnet term, is done in the present paper. We define a set of covariant and gauge-invariant ...

    • Variations of Crest-to-Trough TEC Ratio of the East African Equatorial Anomaly Region 

      Oryema, Bosco; Jurua, Edward; Ssebiyonga, Nicolausi (International Journal of Astrophysics and Space Science 2016, 2015-03)
      In this paper, Vertical Total Electron Content (VTEC) data derived from dual-frequency GPS measurements obtained at two ground stations were used to study the variability of the equatorial ionization anomaly (EIA). The ...

    • Validating the use of scintillation proxies to study ionospheric scintillation over the Ugandan region 

      Amabayo, Emirant B.; Jurua, Edward; Cilliers, PierreJ. (Journal of Atmospheric and Solar-Terrestrial Physics, 2015-03)
      In this study, we compare the standard scintillation indices (S4 and σΦ) from a SCINDA receiver with scintillation proxies (S4p and sDPR||) derived from two IGSGPS receivers. Amplitude (S4) and phase (σΦ) scintillation ...

    • Trends of ionospheric irregularities over African low latitude region during quiet geomagnetic conditions 

      Mungufeni, Patrick; Habarulema, John Bosco; Jurua, Edward (Journal of Atmospheric and Solar-Terrestrial Physics, 2016-01)
      The occurrence patterns of ionospheric irregularities during quiet geomagnetic conditions over the African low latitude region were analysed .GNSS-derived Total Electron Content of the ionosphere data during theperiod2001–2012 ...