Dynamics of Companion Galaxies of Early-Type Galaxies
  We estimated the dynamical masses of 115 early-type galaxies (ETGs) by
analyzing the dynamics of satellite and companion galaxies of these ETGs. We
selected galaxies with absolute magnitudes between -22 and -25 in the
$K_s$-band from the Extragalactic Distance Database (EDD). We also selected 216
spiral galaxies for comparison. We employed a simple model to simulate the
observed dynamical mass from satellite galaxies at various distances. Our
simulations showed that the dynamical masses derived from satellite galaxies
with elliptical orbits would be smaller than those with circular orbits even
they contain the same dark mass halos. Therefore, relationships between the
observed $M_\mathrm{dyn}/M_\mathrm{b}$ distributions and distances would depend
on orbital shapes. From the relationships between our observed
$M_\mathrm{dyn}/M_\mathrm{b}$ distributions and distances, we suggest that the
satellite galaxies of the ETGs have relatively more elliptical orbits than
those of the spiral galaxies have and the $M_\mathrm{dyn}/M_\mathrm{b}$ of the
ETGs are greater than that of the spiral galaxies.
