THE MASSIVE SATELLITE POPULATION OF MILKY-WAY-SIZED GALAXIES

Several occupational distributions for satellite galaxies more massive than m(*) approximate to 4 x 10(7) M-circle dot around Milky-Way (MW)-sized hosts are presented and used to predict the internal dynamics of these satellites as a function of m(*). For the analysis, a large galaxy group mock catalog is constructed on the basis of (sub) halo-to-stellar mass relations fully constrained with currently available observations, namely the galaxy stellar mass function decomposed into centrals and satellites, and the two-point correlation functions at different masses. We find that 6.6% of MW-sized galaxies host two satellites in the mass range of the Small and Large Magellanic Clouds (SMC and LMC, respectively). The probabilities of the MW-sized galaxies having one satellite equal to or larger than the LMC, two satellites equal to or larger than the SMC, or three satellites equal to or larger than Sagittarius (Sgr) are approximate to 0.26, 0.14, and 0.14, respectively. The cumulative satellite mass function of the MW, N-s(>= m(*)), down to the mass of the Fornax dwarf is within the 1 sigma distribution of all the MW-sized galaxies. We find that MW-sized hosts with three satellites more massive than Sgr (as the MW) are among the most common cases. However, the most and second most massive satellites in these systems are smaller than the LMC and SMC by roughly 0.7 and 0.8 dex, respectively. We conclude that the distribution N-s(>= m(*)) for MW-sized galaxies is quite broad, the particular case of the MW being of low frequency but not an outlier. The halo mass of MW-sized galaxies correlates only weakly with N-s(>= m(*)). Then, it is not possible to accurately determine the MW halo mass by means of its N-s(>= m(*)); from our catalog, we constrain a lower limit of 1.38 x 10(12) M-circle dot at the 1 sigma level. Our analysis strongly suggests that the abundance of massive subhalos should agree with the abundance of massive satellites in all MW-sized hosts, i.e., there is not a missing (massive) satellite problem for the Lambda CDM cosmology. However, we confirm that the maximum circular velocity, v(max), of the subhalos of satellites smaller than m(*) similar to 10(8) M-circle dot is systematically larger than the v(max) inferred from current observational studies of the MW bright dwarf satellites; different from previous works, this conclusion is based on an analysis of the overall population of MW-sized galaxies. Some pieces of evidence suggest that the issue could refer only to satellite dwarfs but not to central dwarfs, then environmental processes associated with dwarfs inside host halos combined with supernova-driven core expansion should be on the basis of the lowering of v(max).