  Using the first 25% of DEEP2 Redshift Survey data, we probe the line-of-sight
velocity dispersion profile for isolated galaxies with absolute B-band
magnitude -22<M_B-5log(h)<-21 at z=0.7-1.0, using satellite galaxies as
luminous tracers of the underlying velocity distribution. Measuring the
velocity dispersion beyond a galactocentric radius of ~200 kpc/h (physical)
permits us to determine the total mass, including dark matter, around these
bright galaxies. We find a line-of-sight velocity dispersion (sigma_los) of
162^{+44}_{-30} km/s at ~110 kpc/h, 136^{+26}_{-20} km/s at ~230 kpc/h, and
150^{+55}_{-38} km/s at ~320 kpc/h. Assuming an NFW model for the dark matter
density profile, this corresponds to a mass within r_{200} of
M_200=5.5^{+2.5}_{-2.0} x 10^12 M_Sun/h for our sample of satellite hosts with
mean luminosity ~2.5L*. Roughly $~60% of these host galaxies have early-type
spectra and are red in restframe (U-B) color, consistent with the overall DEEP2
sample in the same luminosity and redshift range. The halo mass determined for
DEEP2 host galaxies is consistent with that measured in the Sloan Digital Sky
Survey for host galaxies within a similar luminosity range relative to M*_B.
This comparison is insensitive to the assumed halo mass profile, and implies an
increase in the dynamical mass-to-light ratio (M_200/L_B) of isolated galaxies
which host satellites by a factor of ~2.5 from z ~ 1 to z ~ 0. Our results are
consistent with scenarios in which galaxies populate dark matter halos
similarly from z ~ 0 to z ~ 1, except for ~1 magnitude of evolution in the
luminosity of all galaxies.
