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Seyfert Galaxies and Their Environment

Published online by Cambridge University Press:  25 May 2016

P. Focardi
Affiliation:
Dipartimento di Astronomia, Università di Bologna, via Zamboni, 33, 40126 Bologna, Italy
B. Kelm
Affiliation:
Dipartimento di Astronomia, Università di Bologna, via Zamboni, 33, 40126 Bologna, Italy
G.G.C. Palumbo
Affiliation:
Dipartimento di Astronomia, Università di Bologna, via Zamboni, 33, 40126 Bologna, Italy

Extract

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The role played by environment on nuclear activity in galaxies is not clear and largely debated (see e.g. Barnes & Hernquist 1992, Kelm 1996). To overcome statistical uncertainties, environment properties of two large samples of Seyfert galaxies (Sy 1 and Sy 2 have been kept separated) have been computed and compared with equivalent size “normal galaxy” sample ones. Seyfert samples have been extracted from the Veron & Veron catalogue (Veron & Veron 1996), whilst “normal galaxies” have been randomly extracted from ZCAT (Huchra 1993). The samples are limited in cz ([1500–9500] km/sec) and contain 149 Sy 1, 173 Sy 2 and 160 “normal galaxies” (hundreds of random extractions from ZCAT). For each galaxy neighbors have been computed (from ZCAT) within two variables radii, R (isolation radius) and r (pair separation), which span [0.2 - 2] h100 Mpc. and [20–90]h100 kpc. respectively. Neighbors must lie also within 700 km/sec from the galaxy. In this way, for each value of R and r, environment of each galaxy has been “quantified”.

Type
Nuclear Activity
Copyright
Copyright © Kluwer 1999 

References

Barnes, J.E. & Hernquist, L. 1992, ARAA., 30, 705 CrossRefGoogle Scholar
Kelm, B. 1996, , Università degli Studi di Bologna Google Scholar
Veron-Cetty, M.P. & Veron, P. 1996, A Catalogue of Quasars and Active Galaxies, ESO Scient. Rep., 17 Google Scholar
Huchra, J.P. et al. 1993, ZCAT Catalogue Google Scholar