Abstract
UNIFIED models1–3 of radio-loud quasars and powerful radio galaxies suggest that they are intrinsically similar objects observed from different angles. This can be tested by comparing the isotropically emitted radiation from the spatially extended nebulae surrounding the nuclei; the unified models predict that the intensities of these emissions should be comparable for the two classes of object. But when this prediction was examined4 for the [O III] 5,007-Å emission line, it was found that quasar [O III] luminosities significantly exceed those of otherwise similar radio galaxies. We have measured the spatially integrated [OII] 3,727-Å emission-line luminosities for a number of quasars and radio galaxies taken from the 3C catalogue. Supplementing our data with values from the literature, we find no systematic difference in the [O II] luminosities. We argue that this emission is indeed isotropic, and that our results are consistent with the unification hypothesis; the [O III] line, on the other hand, may still have a significant component from the nuclear region, and thus be subject to pronounced anisotropic obscuration.
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References
Antonucci, R. R. J. & Miller, J. S. Astrophys. J. 297, 621–632 (1985).
Scheuer, P. A. G. in Superluminal Radio Sources (eds Zensus, J. A. & Pearson, T. J.) 104–113 (Cambridge Univ. Press, 1987).
Barthel, P. D. Astrophys. J. 336, 606–611 (1989).
Jackson, N. & Browne, I. W. A. Nature 343, 43–45 (1990).
Padovani, P. & Urry, C. M. Astrophys. J. 387, 449–457 (1992).
Barthel, P. D., Hooimeyer, J. R., Schilizzi, R. T., Miley, G. K. & Preuss, E. Astrophys. J. 336, 601–605 (1989).
Tadhunter, C. N. in New Windows to the Universe Vol. 2 (eds Sanchez F. & Vasquez, M.) 175–192 (Cambridge Univ. Press, 1990).
Antonucci, R. Nature 299, 605–606 (1982).
Goodrich, R. W. & Cohen, M. H. Astrophys. J. 391, 623–628 (1992).
Antonucci, R. & Barvainis, R. Astrophys. J. 363, L17–L20 (1990).
Djorgovski S., Weir, N., Matthews, K. & Graham, J. R. Astrophys. J. 372, L67–L70 (1991).
Jackson, N. in Physics of Active Galactic Nuclei (eds Duschl, W. J. & Wagner, S. J.) 612–617 (Springer, Berlin, 1992).
Heckman, T. M., Chambers, K. C. & Postman, M. Astrophys. J. 391, 39–47 (1992).
Pier, E. & Krolik, J. Astrophys. J. 401, 99–109 (1992).
Osterbrock, D. Astrophysics of Gaseous Nebulae and Active Galactic Nuclei (University Science Books, Mill Valley, 1989).
Browne, I. W. A. & Jackson, N. in Physics of Active Galactic Nuclei (eds Duschl W. J. & Wagner, S. J.) 618–635 (Springer, Berlin, 1992).
Rawlings, S. & Saunders, R. Nature 349, 138–140 (1991).
Spinrad, H. Publs. astr. Soc. Pacif. 98, 269–284 (1986).
Spinrad, H., Djorgovski, S., Marr, J. & Aguilar, L. Publs. Astr. Soc. Pacif. 97, 932–961 (1985).
Hough, D. H. & Readhead, A. C. S. Astr. J. 98, 1208–1225 (1989).
McCarthy, P. J. thesis, Univ. California, Berkeley (1988).
Jackson, N. & Browne, I. W. A. Mon. Not. R. astr. Soc. 250, 414–421 (1991).
Saunders, R., Baldwin, J. E., Rawlings, S., Warner, P. J. & Miller, L. Mon. Not. R. astr. Soc. 238, 777–790 (1989).
Baum, S. A. & Heckman, T. M. Astrophys. J. 336, 702–771 (1989).
Stockton, A. & MacKenty, J. W. Astrophys. J. 316, 584–596 (1987).
Robinson, A., Binette, L., Fosbury, R. A. E. & Tadhunter, C. N. Mon. Not. R. astr. Soc. 227, 97–114 (1987).
Vestergaard, M. & Barthel, P. D. Astr. J. 105, 456 (1993).
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Hes, R., Barthel, P. & Fosbury, R. Support for a unified model of radio galaxies and quasars from isotropic [OII] emission. Nature 362, 326–328 (1993). https://doi.org/10.1038/362326a0
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DOI: https://doi.org/10.1038/362326a0
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