The radial extent of the Fornax cluster Low Surface Brightness galaxy population

Abstract

AbstractIn this paper we compare the radial distribution of Fornax cluster galaxies selected at different surface brightness values. The bright galaxy (RC3) sample surface brightness distribution peaks at a μBx = 21.5, the Low Surface Brightness (LSB) sample at μBx = 23.7 and the very Low Surface Brigthness (VLSB) sample at μBx = 25.7. The bright galaxy surface density decreases with an exponential scale length of α = 0.5°, the LSB galaxies with α = 1.3° and the VLSB galaxies with α = 2.0°. Thus the LSB and VLSB populations define a mass scale size some 2.5 and 4 times larger than the bright galaxies respectively. The contribution of the VLSB population to the total cluster luminosity is comparible to that of the brighter galaxies. If their mass to light ratios are significantly larger than than that of the bright galaxies they will dominate the mass and possibly account for the missing mass in clusters.