Narrow-line Seyfert 1 galaxies. Relationship between their frequency of occurrence and the large-scale structure of the universe

A previously published method is applied to the SDSS DR 7 data in order to determine the spatial densities of narrow-line and broad-line Seyfert galaxies (NLSs and BLSs) as functions of the density of galaxies in a complete, uniform sample that traces the large-scale structure of the Universe. These relationships are linear and the NLS/BLS ratio is constant, suggesting that NLSs and BLSs comprise a fixed fraction of all galaxies, which does not depend on the local galaxy density. Results obtained using the applied technique support the presence of a higher fraction of red galaxies in regions with higher local galaxy densities.