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Journal of Applied Sciences
  Year: 2007 | Volume: 7 | Issue: 2 | Page No.: 274-279
DOI: 10.3923/jas.2007.274.279
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Seyfert Galaxies: Nuclear Radio Emission and the Unified Schemes

O. Okike, A.A. Ubachukwu and A.E. Chukwude

Seyfer 1 and 2 nomenclatures are generic names arising from the different sizes of the Seyfert nuclear radio emission (D) and the presence or absence of a dusty obscuration torus coincident with the central engine. The size of the line-with emission is another central idea embedded in the projection and orientation scenarios. Linear size and the kinematic Doppler widths (V) are good observational parameters that can be used to test the predictions of the radio-quiet source unification scheme. Since the model favours large size of Seyfert 2, there should be a distribution of linear size within which, if the two subclasses are of the same parent population, Seyfert 2 is not biased towards larger size. We find that at D≤ 100pc, the average extension of nuclear emission for Seyfert 1 is approximately equal to the size of Seyfert 2, suggesting that the dissimilarity in their linear size can be attributed to projection effect. From the relative number of Seyfert 1’s and 2’s having linear size within this range, we estimate that the angle above which a Seyfert 1 is observed as type 2 is 43°. These results, considered together are in favour of the unified model in which Seyfert 2 contains a torus and Seyfert 1’s linear size is smaller than that of 2 due to projection effect.
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How to cite this article:

O. Okike, A.A. Ubachukwu and A.E. Chukwude, 2007. Seyfert Galaxies: Nuclear Radio Emission and the Unified Schemes. Journal of Applied Sciences, 7: 274-279.

DOI: 10.3923/jas.2007.274.279






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