Optical emission-line gas associated with dominant cluster galaxies

Abstract

A representative sample of 13 dominant cluster galaxies is investigatedto determine the presence of the type of emission-line region seenaround M87 and NGC 1275. Half of the sample shows detectable emissionlines where L(H-alpha + forbidden N III) is greater than 10 to the40.5th/erg (H0 = 75). The emission-line luminosity appears tobe related to the X-ray luminosity and/or the cluster richness, and arelationship between optical-line and radio emission is found, whichindicates that the radio source may help form or excite theemission-line gas. Data are also consistent with the cooling accretionflow picture, which is modified by including the role of the radiosource.