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Astron. Astrophys. 330, 447-452 (1998)

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Neural network method for galaxy classification:
the luminosity function of E/S0 in clusters *

Emilio Molinari 1 and Riccardo Smareglia 2

1 Osservatorio Astronomico di Brera, Via Bianchi 46, I-23807 Merate (LC), Italy (molinari@merate.mi.astro.it)
2 Osservatorio Astronomico di Trieste, Via Tiepolo 11, I-34131 Trieste, Italy

Received 24 March 1997 / Accepted 2 October 1997


We present a method based on the non-linear behaviour of neural network for the identification of the early-type population in the cores of galaxy clusters. A Kohonen Self Organising Map applied on a three-colour photometric catalogue of objects enabled us to select in each passband the elliptical galaxies. We measured in this way the luminosity function of the E/S0 galaxies selected in this way. Such luminosity functions show peculiarities which disfavour the hypothesis of its universality often claimed for rich clusters and that can be related to the past dynamical history of the cluster as a whole.

Key words: galaxies: clusters: general – galaxies: elliptical and lenticular – galaxies: luminosity function – galaxies: photometry – methods: miscellaneous

* Based on observations made at the European Southern Observatory (ESO), La Silla, Chile

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© European Southern Observatory (ESO) 1998

Online publication: January 16, 1998