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Title:
The relative number of Seyfert 2 galaxies. I - Spectra of emission-line galaxies in the Wasilewski field
Authors:
Osterbrock, Donald E.; Shaw, Richard A.
Affiliation:
AA(Lick Observatory; California, University, Santa Cruz), AB(Lick Observatory; California, University, Santa Cruz)
Publication:
Astrophysical Journal, Part 1 (ISSN 0004-637X), vol. 327, April 1, 1988, p. 89-98. (ApJ Homepage)
Publication Date:
04/1988
Category:
Astrophysics
Origin:
STI
NASA/STI Keywords:
EMISSION SPECTRA, H II REGIONS, LINE SPECTRA, RED SHIFT, SEYFERT GALAXIES, STELLAR LUMINOSITY, GALACTIC NUCLEI, H ALPHA LINE, H BETA LINE, SIGNAL TO NOISE RATIOS
DOI:
10.1086/166172
Bibliographic Code:
1988ApJ...327...89O

Abstract

Slit spectra were obtained of all the Seyfert galaxy candidates and many other emission-line galaxies discovered (or recovered) by Wasilewski in his objective-prism survey centered on the region of North Galactic Pole. Redshifts and relative emission-line fluxes were measured for these galaxies, and all of their spectra were classified. Per unit volume of space, the relative numbers of Seyfert (1+1.5) to Seyfert (1.8+1.9) to Seyfert 2 are approximately 0.1/0.1/0.8. If the same galaxies were to evolve through all these stages, they would spend most of their AGN lifetimes as Seyfert 2s. If all Seyfert nuclei were similar objects with central broad-line regions hidden by obscuring disks to various extents, the disks would be thick and the line broadening due to any presumed rotational or radial velocity field in the plane of the disk would be greatly reduced by projection effects.

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