Anisotropic ionizing radiation in NGC5252

Clive Tadhunter, Zlatan Tsvetanov

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THE different kinds of active galactic nuclei (AGNs) and quasars may be fundamentally similar, and owe their observed differences to anisotropy in the distribution of their emitted radiation: apparently different objects may then be the same thing seen from different viewpoints. In particular, it has been proposed that narrow-line Seyfert 2 galaxies are Seyfert 1 galaxies for which the broad-line and continuum emitting regions are hidden by obscuring material along our line of sight1,2 Here we present narrow-band imaging observations of the Seyfert 2 galaxy NGC5252 which strongly support such unifying hypotheses. Images in the light of the [O III] line at λ = 5,007 Å reveal a sharply defined bi-conical structure extending to a maximum radius of ∼33 kpc (H0 = 50 km s-1 Mpc-11) along the radio-emission axis. This is just the type of structure expected if the ionizing-radiation field from the nucleus is anisotropic. A map of the ratio of the [O III] and Hα lines shows a central band perpendicular to the cones that we identify as the disk or torus responsible for collimating the radiation field.

Original languageEnglish
Pages (from-to)422-424
Number of pages3
Issue number6241
Publication statusPublished - 1989
Externally publishedYes


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Cite this

Tadhunter, C., & Tsvetanov, Z. (1989). Anisotropic ionizing radiation in NGC5252. Nature, 341(6241), 422-424.