Luminosity versus phase-space-density relation of galaxies revisited

We reexamined the correlation between the B-T magnitude and the phase-space -density parameter w = (D-2(25) v(o))(-1) of galaxies for the Virgo, the Co ma, the Fornax, and the Perseus clusters in an effort to better understand the physical underpinning of the fundamental plane. A tight correlation (B- T = a log w + b) common to different morphological types of galaxies (E, S0 , S) was found for the Virgo and the Coma clusters, with a = 1.87 +/- 0.10 and 1.33 +/- 0.11, respectively. An investigation using only E galaxies was made for the four clusters. The results indicated that the empirical linea r relation might be common among the Coma, the Fornax, and the Perseus clus ters, with the Virgo Cluster showing deviation. This relation, which is ano ther way to project the fundamental plane, has an expression insensitive to the morphology and may be suitable for treating galaxies of different morp hological types collectively.