More Satellites of Spiral Galaxies

We present a revised and expanded catalog of satellite galaxies of a set ofisolated spiral galaxies similar in luminosity to the Milky Way. This sample of115 satellites, 69 of which were discovered in our multifiber redshift survey,is used to further probe the results obtained from the original sample(Zaritsky et al. 1993). The satellites are, by definition, at projectedseparations <~ 500 kpc, have absolute recessional velocity differences withrespect to the parent spiral of less than 500 km/s and are at least 2.2 magfainter than their associated primary galaxy. A key characteristic of thissurvey is the strict isolation of these systems, which simplifies any dynamicalanalysis. We find no evidence for a decrease in the velocity dispersion of thesatellite system as a function of radius out to galactocentric radii of 400kpc, suggesting that the halo extends well beyond 200 kpc. Furthermore, the newsample affirms our previous conclusions (Zaritsky et al. 1993) that (1) thevelocity difference between a satellite and its primary is not stronglycorrelated with the rotation speed of the primary, (2) the system of satelliteshas a slight net rotation (34 \pm 14 km\s) in the same sense as the primary'sdisk, and (3) that the halo mass of an ~ L* spiral galaxy is in excess of 2 x10^{12} solar masses.Comment: Accepted for publication in Ap