Ratios of forbidden [OIII] λλ4959,5007 and [NII] λλ6548,6583 lines in nearby narrow emission line galaxies
Galaxies with narrow emission lines play a crucial role in testing the theoretical values of transition probabilities, especially for lines that need conditions that are hard to produce in laboratory plasma, and hence the theoretical values could not be checked in experimental measurements. In this...
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Frontiers Media S.A.
2025-05-01
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| author | Natas̆a Bon Edi Bon Paola Marziani Luka C̆. Popović |
| author_facet | Natas̆a Bon Edi Bon Paola Marziani Luka C̆. Popović |
| author_sort | Natas̆a Bon |
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| description | Galaxies with narrow emission lines play a crucial role in testing the theoretical values of transition probabilities, especially for lines that need conditions that are hard to produce in laboratory plasma, and hence the theoretical values could not be checked in experimental measurements. In this paper, we explore the [O III]λλ4959,5007 and the [N II]λλ6,548, 6,583 doublets and their line ratios in a volume limited samples (0.01 ⩽ z ⩽ 0.05) of Sy2, LINERs, composite objects and star-forming galaxies, that zooms in the central region of these objects. Our results confirm that the theoretical line ratios R([OIII])=2.98 and R([NII])=3.05 as predicted by Storey and Zeippen (2000) are consistent with observations of HII regions, for both line ratios. This agreement occurs under conditions minimally affected by reddening, corresponding to total-to-selective extinction ratios (RV) between 3.1 and 4.1. In contrast, Seyfert 2, LINER, and composite galaxies confirm the same theoretical prediction of the [OIII] line ratios in the case of stronger reddening (2.1≤RV≤3.1), while [NII] ratios stays slightly lower than predicted by Storey and Zeippen (2000), aligning more closer to the values reported by Galavis et al. (1997), or indicating a presence of environmental conditions that affects these line ratios. This discrepancy in [NII] ratios suggests that, beyond reddening effects, the physical conditions in the [NII]-emitting regions of active galaxies differ from those in HII regions. Shocks, variations in electron density, ionization mechanisms, and gas or dust composition may contribute to these differences. |
| format | Article |
| id | doaj-art-dbc59f56caae4c8c988535ab65737141 |
| institution | Kabale University |
| issn | 2296-987X |
| language | English |
| publishDate | 2025-05-01 |
| publisher | Frontiers Media S.A. |
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| series | Frontiers in Astronomy and Space Sciences |
| spelling | doaj-art-dbc59f56caae4c8c988535ab657371412025-08-20T03:52:47ZengFrontiers Media S.A.Frontiers in Astronomy and Space Sciences2296-987X2025-05-011210.3389/fspas.2025.15405221540522Ratios of forbidden [OIII] λλ4959,5007 and [NII] λλ6548,6583 lines in nearby narrow emission line galaxiesNatas̆a Bon0Edi Bon1Paola Marziani2Luka C̆. Popović3Astronomical Observatory, Belgrade, SerbiaAstronomical Observatory, Belgrade, SerbiaOsservatorio Astronomico di Padova (INAF), Padua, Veneto, ItalyAstronomical Observatory, Belgrade, SerbiaGalaxies with narrow emission lines play a crucial role in testing the theoretical values of transition probabilities, especially for lines that need conditions that are hard to produce in laboratory plasma, and hence the theoretical values could not be checked in experimental measurements. In this paper, we explore the [O III]λλ4959,5007 and the [N II]λλ6,548, 6,583 doublets and their line ratios in a volume limited samples (0.01 ⩽ z ⩽ 0.05) of Sy2, LINERs, composite objects and star-forming galaxies, that zooms in the central region of these objects. Our results confirm that the theoretical line ratios R([OIII])=2.98 and R([NII])=3.05 as predicted by Storey and Zeippen (2000) are consistent with observations of HII regions, for both line ratios. This agreement occurs under conditions minimally affected by reddening, corresponding to total-to-selective extinction ratios (RV) between 3.1 and 4.1. In contrast, Seyfert 2, LINER, and composite galaxies confirm the same theoretical prediction of the [OIII] line ratios in the case of stronger reddening (2.1≤RV≤3.1), while [NII] ratios stays slightly lower than predicted by Storey and Zeippen (2000), aligning more closer to the values reported by Galavis et al. (1997), or indicating a presence of environmental conditions that affects these line ratios. This discrepancy in [NII] ratios suggests that, beyond reddening effects, the physical conditions in the [NII]-emitting regions of active galaxies differ from those in HII regions. Shocks, variations in electron density, ionization mechanisms, and gas or dust composition may contribute to these differences.https://www.frontiersin.org/articles/10.3389/fspas.2025.1540522/fullgalaxiesemission line galaxiesseyfert-galaxiesstar forming galaxieslinersactive gala×ies |
| spellingShingle | Natas̆a Bon Edi Bon Paola Marziani Luka C̆. Popović Ratios of forbidden [OIII] λλ4959,5007 and [NII] λλ6548,6583 lines in nearby narrow emission line galaxies Frontiers in Astronomy and Space Sciences galaxies emission line galaxies seyfert-galaxies star forming galaxies liners active gala×ies |
| title | Ratios of forbidden [OIII] λλ4959,5007 and [NII] λλ6548,6583 lines in nearby narrow emission line galaxies |
| title_full | Ratios of forbidden [OIII] λλ4959,5007 and [NII] λλ6548,6583 lines in nearby narrow emission line galaxies |
| title_fullStr | Ratios of forbidden [OIII] λλ4959,5007 and [NII] λλ6548,6583 lines in nearby narrow emission line galaxies |
| title_full_unstemmed | Ratios of forbidden [OIII] λλ4959,5007 and [NII] λλ6548,6583 lines in nearby narrow emission line galaxies |
| title_short | Ratios of forbidden [OIII] λλ4959,5007 and [NII] λλ6548,6583 lines in nearby narrow emission line galaxies |
| title_sort | ratios of forbidden oiii λλ4959 5007 and nii λλ6548 6583 lines in nearby narrow emission line galaxies |
| topic | galaxies emission line galaxies seyfert-galaxies star forming galaxies liners active gala×ies |
| url | https://www.frontiersin.org/articles/10.3389/fspas.2025.1540522/full |
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