A. Rodriguez-Puebla, V. Avila-Reese, N. Drory
Occupational distributions for satellite galaxies ms>4E7Msun around Milky-Way-sized(MW-s) hosts are presented and used to predict the internal dynamics of these sats. For the analysis, a galaxy group mock catalog is constructed on the basis of (sub)halo-to-stellar mass relations fully constrained with available observations; the stellar mass function of centrals and satellites, and the 2-point correlation function. 6.6% of MW-s galaxies host 2 sats in the mass range of the Small and Large Magellanic Clouds (SMC and LMC). The probabilities of the MW-s galaxies to have 1 sat>= the LMC or 2 sats>= the SMC or 3 sats>= Saggitarius (Sgr) are ~0.26,0.14, and 0.14. MW-s hosting 3 sats>= Sgr (as the MW) are among the most common cases. However, the most and 2nd most massive sats in these systems are < LMC and SMC by ~0.7 and 0.8dex. The N(>ms) for MW-s galaxies is broad, the case of the MW being of low frequency but not an outlier. The Mh of MW-s galaxies correlates only weakly with N(>ms). Then, it is not possible to accurately determine the MW halo mass by means of N(>ms); we constrain a lower limit 1.38E12Msun at 1sig level. Our analysis strongly suggests that the abundance of massive subhalos agree with the abundance of massive sats in all MW-s hosts, i.e. there is not a (massive) sat missing problem for the LCDM. However, we confirm that the max circular vel, vmax, of the subhalos of sats ms<10^8Msun is systematically larger than the vmax inferred from current observational studies of the MW bright dwarf sats; at difference of previous works, this conclusion is based on an analysis of the overall population of MW-s galaxies. Some pieces of evidence suggest that the issue could refer only to sat dwarfs but not to central dwarfs; then, environmental processes associated to dwarfs inside host halos combined with SN-driven core expansion should be at the basis of the lowering of vmax.
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http://arxiv.org/abs/1306.4328
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