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 } .
Superimposed onto one quadrant of the cluster field there 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 .
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 ^ { \prime } } < –16.6 , is well fitted by a Schechter function with M _ { g ^ { \prime } } ^ { * } = -21.2 \pm 0.8 and \alpha = -1.2 \pm 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 g ^ { \prime } and i ^ { \prime } bands agrees with the photometric results .
The mass of the system , M \sim 1.9 \times 10 ^ { 14 } h ^ { -1 } _ { 70 } M _ { \odot } , its M/L of 445 h _ { 70 } M _ { \odot } /L _ { B } _ { \odot } and L _ { X } of 11 \times 10 ^ { 43 } h ^ { -2 } _ { 70 } ergs s ^ { -1 } ( bolometric ) suggest that this system is the second example of known fossil cluster , after RX J1552.2+2013 , confirmed in the literature .