Phéneas Nkundabakura

University of Rwanda

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Théophile Nsengimana

University of Rwanda

M. Pović

Instituto de Astrofísica de Andalucía

Antoine Mahoro

South African Radio Astronomy Observatory

P. Väisänen

Istituto Nazionale di Fisica Nucleare, Sezione di Perugia

K. van der Heyden

University of Cape Town

Aloys Iyamuremye

University of Rwanda

Leon Rugema Mugabo

University of Rwanda

Pascasie Nyirahabimana

University of Rwanda

Hiroaki Ozawa

Naruto University of Education

Céline Byukusenge

University of Rwanda

Cooperative Institutions

University of Rwanda

South African Radio Astronomy Observatory

Rwanda Development Board

University of Southampton

University of Cape Town

University of Kigali

National Institute for Astrophysics

Mbarara University of Science and Technology

Centre National de la Recherche Scientifique

African Institute for Mathematical Sciences

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Determination of K4000 of potential blazar candidates among EGRET unidentified gamma-ray sources

Proceedings of the International Astronomical Union (2019)

Emmanuel Uwitonze Phéneas Nkundabakura Tom Mutabazi

Abstract Blazars are radio-loud Active Galactic Nuclei (AGN) with relativistic jets oriented towards the observer’s line-of-sight. Based on their optical spectra, blazars may be classified as flat-spectrum radio quasars (FSRQs) or BL Lacs. FSRQs are more luminous blazars with both narrow and broad emission and absorption lines, while BL Lacs are less luminous and featureless. Recent studies show that blazars dominate (˜93%) the already-identified EGRET sources (142), suggesting that among the unidentified sources (129) there could still be faint blazars. Due to the presence of a strong non-thermal component inside their jets, blazars are found to display a weaker depression at ˜4000 Å (K 4000 ≤ 0.4). In this study, we aimed at determining the K 4000 break for a selected sample among the potential blazar candidates from unidentified EGRET sources to confirm their blazar nature. We used two blazar candidates, 3EG J1800-0146 and 3EG J1709-0817 associated with radio counterparts, J1802-0207 and J1713-0817, respectively. Their optical counterparts were obtained through spectroscopic observations using Robert Stobie spectrograph (RSS) at the Southern African Large Telescope (SALT) in South Africa. The observed Ca II H & K lines depression at ˜4000 Å in spectra of these sources show a shallow depression, K 4000 = 0.35 ± 0.02 and 0.24 ± 0.01, respectively, suggesting that these sources are blazar candidates. Moreover, the redshifts z = 0.165 and 0.26 measured in their spectra confirm the extragalactic nature of these sources.

10.1017/s1743921320003336

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The [OIII] profiles of far-infrared active and non-active optically-selected green valley galaxies

arXiv (Cornell University) (2023)

Antoine Mahoro P. Väisänen M. Pović Phéneas Nkundabakura K. van der Heyden

We present a study of the $\rm{[OIII]λ\,5007}$ line profile in a sub-sample of 8 active galactic nuclei (AGN) and 6 non-AGN in the optically-selected green valley at $\rm{z\,<\,0.5}$ using long-slit spectroscopic observations with the 11 m Southern African Large Telescope. Gaussian decomposition of the line profile was performed to study its different components. We observe that the AGN profile is more complex than the non-AGN one. In particular, in most AGN (5/8) we detect a blue wing of the line. We derive the FWHM velocities of the wing and systemic component, and find that AGN show higher FWHM velocity than non-AGN in their core component. We also find that the AGN show blue wings with a median velocity width of approximately 600 $\rm{km\,s^{-1}}$, and a velocity offset from the core component in the range -90 to -350 $\rm{km\,s^{-1}}$, in contrast to the non-AGN galaxies, where we do not detect blue wings in any of their $\rm{[OIII]λ\,5007}$ line profiles. Using spatial information in our spectra, we show that at least three of the outflow candidate galaxies have centrally driven gas outflows extending across the whole galaxy. Moreover, these are also the galaxies which are located on the main sequence of star formation, raising the possibility that the AGN in our sample are influencing SF of their host galaxies (such as positive feedback). This is in agreement with our previous work where we studied SF, morphology, and stellar population properties of a sample of green valley AGN and non-AGN galaxies.

Doubly ionized oxygen

Line (geometry)

10.48550/arxiv.2304.09284

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Review and tests of methods for the determination of the solar cell junction ideality factors

Solar Energy (2006)

M. Bashahu Phéneas Nkundabakura

Biasing

Intensity

10.1016/j.solener.2006.11.002

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Citations (102)

The [O iii] Profiles of Far-infrared Active and Inactive Optically Selected Green Valley Galaxies

The Astrophysical Journal (2023)

Antoine Mahoro P. Väisänen M. Pović Phéneas Nkundabakura K. van der Heyden

We present a study of the $\rm{[OIII]\lambda\,5007}$ line profile in a sub-sample of 8 active galactic nuclei (AGN) and 6 non-AGN in the optically-selected green valley at $\rm{z\,<\,0.5}$ using long-slit spectroscopic observations with the 11 m Southern African Large Telescope. Gaussian decomposition of the line profile was performed to study its different components. We observe that the AGN profile is more complex than the non-AGN one. In particular, in most AGN (5/8) we detect a blue wing of the line. We derive the FWHM velocities of the wing and systemic component, and find that AGN show higher FWHM velocity than non-AGN in their core component. We also find that the AGN show blue wings with a median velocity width of approximately 600 $\rm{km\,s^{-1}}$, and a velocity offset from the core component in the range -90 to -350 $\rm{km\,s^{-1}}$, in contrast to the non-AGN galaxies, where we do not detect blue wings in any of their $\rm{[OIII]\lambda\,5007}$ line profiles. Using spatial information in our spectra, we show that at least three of the outflow candidate galaxies have centrally driven gas outflows extending across the whole galaxy. Moreover, these are also the galaxies which are located on the main sequence of star formation, raising the possibility that the AGN in our sample are influencing SF of their host galaxies (such as positive feedback). This is in agreement with our previous work where we studied SF, morphology, and stellar population properties of a sample of green valley AGN and non-AGN galaxies.

Doubly ionized oxygen

Line (geometry)

10.3847/1538-4357/accea1

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The search for blazars among the unidentified EGRET sources

AIP conference proceedings (2012)

P. J. Meintjes Phéneas Nkundabakura

Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation P. J. Meintjes, P. Nkundabakura; The search for blazars among the unidentified EGRET sources. AIP Conference Proceedings 5 December 2012; 1505 (1): 554–557. https://doi.org/10.1063/1.4772320 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioAIP Conference Proceedings Search Advanced Search |Citation Search

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10.1063/1.4772320

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Usage of modernized tools and innovative methods in teaching and learning mathematics and sciences: A case of 10 districts in Rwanda

Education and Information Technologies (2023)

Phéneas Nkundabakura Théophile Nsengimana Pascasie Nyirahabimana Jean Baptiste Nkurunziza Concilie Mukamwambali

Mindset

School teachers

10.1007/s10639-023-11666-z

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Status of astronomy in Rwanda and volunteer work at Kigali Institute of Education (KIE)

Proceedings of the International Astronomical Union (2012)

M. Pović Phéneas Nkundabakura J. Uwamahoro

Until 2009, astronomy was undeveloped in Rwanda, without astronomy courses at universities and schools, astronomical facilities, or any outreach programmes. With the international year of astronomy in 2009, Dr. Pheneas Nkundabakura and Dr. Jean Uwamahoro from the KIE Maths-Physics department, both graduates from the South African NASSP Programme ( http://www.star.ac.za ), started a program of implementing the astronomical knowledge at schools and universities. During the same year 2009, IAU donated 100 galileoscopes for the secondary schools, and several astronomy workshops were organised for the teachers. IAU donated also 5 laptops to help students and lecturers to learn and use astronomy software. With this, KIE students have now a possibility to choose astronomy/space science for their undergraduate final year research projects. Moreover, there is an ongoing effort to look for further collaboration towards establishing the first astronomical facility (observatory) in the country.

Outreach

10.1017/s1743921314012022

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Properties of X-ray detected far-IR AGN in the green valley

Proceedings of the International Astronomical Union (2019)

Antoine Mahoro M. Pović P. Väisänen Phéneas Nkundabakura Beatrice Nyiransengiyumva

In this study, we analysed active galactic nuclei in the "green valley" by comparing active and non-active galaxies using data from the COSMOS field. We found that most of our X-ray detected active galactic nuclei with far-infrared emission have star formation rates higher than the ones of normal galaxies of the same stellar mass range.

10.1017/s174392132000277x

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Analysis of daily global irradiation data for five sites in Rwanda and one in Senegal

Renewable Energy (1994)

M. Bashahu Phéneas Nkundabakura

Sunshine duration

10.1016/0960-1481(94)90050-7

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Citations (17)

Star formation in far-IR AGN and non-AGN galaxies in the green valley – II. Morphological analysis

Monthly Notices of the Royal Astronomical Society (2019)

Antoine Mahoro M. Pović Phéneas Nkundabakura Beatrice Nyiransengiyumva P. Väisänen

This paper studies morphological properties of 103 green valley FIR active and 2609 non-active galaxies presented in Mahoro, Pović & Nkundabakura (2017). The photometric data from the COSMOS survey were used, and the morphological parameters, such as Abraham and Conselice–Bershady concentration indices, Gini, M20 moment of light, and asymmetry, were analysed taking into account public catalogues. Furthermore, a visual classification of galaxies was performed. We found that the fraction of peculiar galaxies with clear signs of interactions and mergers is significantly higher in AGNs (38 per cent) than non-AGN (19 per cent) green valley galaxies, while non-AGN galaxies from our sample are predominantly spirals (46 per cent). We found that the largest fraction of our green valley galaxies is located on the main sequence of star formation, independently on morphology, which is in contrast with most of previous studies carried out in optical. We also found that FIR AGN green valley galaxies have significantly higher star formation rates in all analysed morphological types. Therefore, our results suggest that interactions and mergers obtained in the high fraction of FIR AGNs contribute significantly to high star formation rates observed in the selected sample, but are not the only mechanism responsible for enhancing star formation, and others such as AGN positive feedback could contribute as well. In future we will study in more details the possibility of AGN positive feedback through the spectroscopic analysis of public and our SALT data.

10.1093/mnras/stz434

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Citations (12)