Velocity dispersion, mass, and the luminosity function of the fossil cluster RX J1416.4+2315

We study the properties of the fossil cluster RX J1416.4 + 2315 through g'- and i'- band imaging and spectroscopy of 25 member galaxies. The system is at a mean redshift of 0.137 and has a velocity dispersion of 584 km s(-1). Superposed onto one quadrant of the cluster field is a group of five galaxies at a mean redshift of 0.131, which, if included as part of the cluster, increases the velocity dispersion to 846 km s(-1). The central object of RX J1416.4 + 2315 is a normal elliptical galaxy with no cD envelope. The luminosity function of the system, estimated by the number counts and statistical background correction in the range -22:6 < M-g' < -16:6, is well fitted by a Schechter function with M-g'(*) = 21.2 +/- 0.8 and alpha = 1.2 +/- 0.2 (H-0 = 70 km s(-1) Mpc(-1), Omega(M) = 0:3, Omega(Lambda) = 0.7). The luminosity function obtained from the spectroscopically confirmed members in both the g' and i' bands agrees with the photometric results. The mass of the system, M similar to 1.9 x 10(14) h(70)(-1) M-circle dot, its M/L of 445 h(70) M-circle dot L-B circle dot(-1) and L-X of 11 x 10(43) h(70)(-2) ergs s(-1) bolometric) suggest that this system is the second example of a known fossil cluster, after RX J1552.2 + 2013, confirmed in the literature.