Search

Low-mass satellites around Milky Way (MW)-like galaxies are important probes of small-scale structure and galaxy formation. However, confirmation of satellite candidates with distance measurements remains a key barrier to fast progress in the Local Volume (LV). We measure the surface brightness fluctuation distances to recently cataloged candidate dwarf satellites around 10 massive hosts within D < 12 Mpc to confirm association. The satellite systems of these hosts are complete and mostly cleaned of contaminants down to Mg ∼ −9 to −10, within the area of the search footprints. Joining this sample with hosts surveyed to comparable or better completeness in the literature, we explore how well cosmological simulations combined with common stellar to halo mass relations (SHMR) match observed satellite luminosity functions in the classical satellite luminosity regime. Adopting an SHMR that matches hydrodynamic simulations, we find that the predicted overall satellite abundance agrees well with the observations. The MW is remarkably typical in its luminosity function among LV hosts. We find that the host-to-host scatter predicted by the model is in close agreement with the scatter between the observed systems, once the different masses of the observed systems are taken into account. However, we find significant evidence that the observed systems have more bright and fewer faint satellites than the SHMR model predicts, possibly necessitating a higher normalization of the SHMR around halo masses of 1011M⊙ or significantly greater scatter than present in common SHMRs. These results demonstrate the utility of nearby satellite systems in inferring the galaxy–subhalo connection in the low-mass regime. [ABSTRACT FROM AUTHOR]

The radial spatial distribution of low-mass satellites around a Milky Way (MW)-like host is an important benchmark for simulations of small-scale structure. The distribution is sensitive to the disruption of subhalos by the central disk and can indicate whether the disruption observed in simulations of MW analogs is artificial (i.e., numerical) or physical in origin. We consider a sample of 12 well-surveyed satellite systems of MW-like hosts in the Local Volume (D < 12 Mpc) that are complete to MV < −9 and within 150 projected kpc. We investigate the radial distribution of satellites and compare with ΛCDM cosmological simulations, including big-box cosmological simulations and high-resolution zoom-in simulations of MW-sized halos. We find that the observed satellites are significantly more centrally concentrated than the simulated systems. Several of the observed hosts, including the MW, are ∼2σ outliers relative to the simulated hosts in being too concentrated, while none of the observed hosts are less centrally concentrated than the simulations. This result is robust to different ways of measuring the radial concentration. We find that this discrepancy is more significant for bright, MV < −12 satellites, suggestive that this is not the result of observational incompleteness. We argue that the discrepancy is possibly due to artificial disruption in the simulations, but, if so, this has important ramifications for what relation between stellar mass and halo mass is allowed in the low-mass regime by the observed abundance of satellites. [ABSTRACT FROM AUTHOR]