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Astron. Astrophys. 343, 760-774 (1999)

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The rich cluster of galaxies ABCG 85

IV. Emission line galaxies, luminosity function and dynamical properties *

F. Durret 1,2, D. Gerbal 1,2, C. Lobo 3 and C. Pichon 1,4,5

1 Institut d'Astrophysique de Paris, CNRS, 98bis Bd Arago, F-75014 Paris, France
2 DAEC, Observatoire de Paris, Université Paris VII, CNRS (UA 173), F-92195 Meudon Cedex, France
3 Osservatorio Astronomico di Brera, via Brera 28, I-20121 Milano, Italy
4 Observatoire de Strasbourg, 11 rue de l'Observatoire, F-67000 Strasbourg, France
5 Astronomisches Institut, Universitaet Basel, Venusstrasse 7, CH-4102 Binningen, Switzerland

Received 6 November 1998 / Accepted 22 December 1998


This paper is the fourth of a series dealing with the cluster of galaxies ABCG 85. Using our two extensive photometric and spectroscopic catalogues (with 4232 and 551 galaxies respectively), we discuss here three topics derived from optical data. First, we present the properties of emission line versus non-emission line galaxies, showing that their spatial distributions somewhat differ; emission line galaxies tend to be more concentrated in the south region where groups appear to be falling onto the main cluster, in agreement with the hypothesis (presented in our previous paper) that this infall may create a shock which can heat the X-ray emitting gas and also enhance star formation in galaxies. Then, we analyze the luminosity function in the R band, which shows the presence of a dip similar to that observed in other clusters at comparable absolute magnitudes; this result is interpreted as due to comparable distributions of spirals, ellipticals and dwarfs in these various clusters. Finally, we present the dynamical analysis of the cluster using parametric and non-parametric methods and compare the dynamical mass profiles obtained from the X-ray and optical data.

Key words: methods: analytical – methods: numerical – galaxies: clusters: general – galaxies: clusters: individual: ABCG 85 – galaxies: luminosity function, mass function

* Based on observations collected at the European Southern Observatory, La Silla, Chile

Send offprint requests to: F. Durret (durret@iap.fr)

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© European Southern Observatory (ESO) 1999

Online publication: March 1, 1999