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Astron. Astrophys. 356, 435-444 (2000)

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The luminosity function of MS 2255.7+2039 at z = 0.288 *

M. Näslund, C. Fransson and M. Huldtgren

Stockholm Observatory, 133 36 Saltsjöbaden, Sweden

Received 1 July 1999 / Accepted 11 February 2000


The luminosity function of MS2255.7+2039 at [FORMULA] is determined down to a total magnitude of [FORMULA], corresponding to [FORMULA]. The data are corrected for incompleteness and crowding using detailed simulations. We find that the luminosity function is steeper than a standard Schechter function at faint magnitudes, and shows an excess of galaxies below [FORMULA]. After corrections for light loss and crowding, the data can be described by a sum of two Schechter functions, one with [FORMULA] and [FORMULA], and one steeper with [FORMULA] and [FORMULA], representing the dwarf population. A straight-line fit to the faint part yields a slope similar to the Schechter [FORMULA] of the dwarf population. The luminosity function of MS2255.7+2039 is compared to other clusters at lower redshifts, and does not show any significant difference. The redshift range for clusters in which increased number of dwarf galaxies have been found is therefore extended to higher redshifts.

Key words: galaxies: clusters: general – galaxies: clusters: individual: MS2255.7+2039 – galaxies: evolution – galaxies: formation – galaxies: luminosity function, mass function – cosmology: observations

* Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.

Correspondence to: magnus@astro.su.se

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© European Southern Observatory (ESO) 2000

Online publication: April 10, 2000