Environmental effects on the Coma cluster luminosity function

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Using our catalogue of V₂₆.₅ isophotal magnitudes for 6756 galaxies in a region covering 60 × 25 arcmin² in the center of the Coma cluster, plus 267 galaxies in a region of 9.7 × 9.4 arcmin² around NGC 4839, we derive the luminosity function in the magnitude range 13.5≤ V₂₆.₅ < 21.0 (corresponding to the absolute magnitude range -22.24 < Mᵥ₂₆.₅ ≤ -14.74). The luminosity function for this region is well fitted by the combination of a gaussian in its bright part and of a steep Schechter function (of index α=-1.8) in its faint part. Luminosity functions derived for individual regions surrounding the brightest galaxies show less steep slopes, strongly suggesting the existence of environmental effects. The implications of such effects and galaxy formation scenarios are discussed.