The spatial distribution of active galactic nuclei. I - The density of Seyfert galaxies and liners
J. P. Huchra, R. Burg
Abstract
J. P. Huchra, R. Burg
Abstract
We define and use a "complete" sample of 25 Seyfert 1 and 23 Seyfert 2 galaxies within the spatial bounds and magnitude limit of the CfA Redshift Survey. The spatial density of Seyfert galaxies is calculated; classical Seyfert galaxies comprise 1.3% of all galaxies at integrated absolute magnitude - 20.0. This result is in substantial agreement with our previous estimates based on considerably more incomplete samples. The fraction of galaxies that are active galactic nuclei (AGNs) rises steeply with absolute magnitude. Three of the five galaxies in the CfA survey (2399 galaxies total) more luminous than M_B_ = - 21.5 are AGNs (H_0_ = 100 km s^-1^ Mpc^-1^; the two most luminous galaxies in the CfA survey are both Seyfert 1 galaxies. The integrated space density of Seyfert 2 galaxies is found to be approximately twice as large as the space density of Seyfert 1 galaxies. We also attempt to measure the spatial density of other types of "active" galactic nuclei-in particular LINERs, but find severe selection effects in our optically selected sample of such objects.
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We define and use a "complete" sample of 25 Seyfert 1 and 23 Seyfert 2 galaxies within the spatial bounds and magnitude limit of the CfA Redshift Survey. The spatial density of Seyfert galaxies is calculated; classical Seyfert galaxies comprise 1.3% of all galaxies at integrated absolute magnitude - 20.0. This result is in substantial agreement with our previous estimates based on considerably more incomplete samples. The fraction of galaxies that are active galactic nuclei (AGNs) rises steeply with absolute magnitude. Three of the five galaxies in the CfA survey (2399 galaxies total) more luminous than M_B_ = - 21.5 are AGNs (H_0_ = 100 km s^-1^ Mpc^-1^; the two most luminous galaxies in the CfA survey are both Seyfert 1 galaxies. The integrated space density of Seyfert 2 galaxies is found to be approximately twice as large as the space density of Seyfert 1 galaxies. We also attempt to measure the spatial density of other types of "active" galactic nuclei-in particular LINERs, but find severe selection effects in our optically selected sample of such objects.
Key concepts: Physics, Astrophysics, Active galactic nucleus, Galaxy, Luminous infrared galaxy, Astronomy, Luminosity, Redshift