The distribution of ionized gas in early-type galaxies. III. M/L determinations based on triaxial models.

The velocity fields of ionized gas disks in four elliptical galaxies have been exploited to derive the mass-to-light ratios as function of radial distance. For each galaxy, namely NGC 1453, NGC 2974, NGC 5077 and NGC 7097, we derive a set of intrinsic shapes of the stellar component and viewing angles that are consistent with the observed ellipticities and orientation of the isophotes. A least-squares fit to the observed velocity field gives the set of parameters defining the potential that best reproduces the kinematics of the ionized gas disk as well as the mass density and light density radial profiles. For three galaxies a satisfactory model is found. The M/L ratio does change within individual galaxies, though not showing any systematic increase with radius and has a mean value of about 5Msun_/L_Bsun out to ~1R_e.