Demise of Faint Satellites around Isolated Early-type Galaxies
  The hierarchical galaxy formation scenario in the Cold Dark Matter cosmogony
with a non-vanishing cosmological constant and geometrically flat space has
been very successful in explaining the large-scale distribution of galaxies.
However, there have been claims that the scenario predicts too many satellite
galaxies associated with massive galaxies compared to observations, called the
missing satellite galaxy problem. Isolated groups of galaxies hosted by
passively evolving massive early-type galaxies are ideal laboratories for
finding the missing physics in the current theory. Here we report from a deep
spectroscopic survey of such satellite systems that isolated massive early-type
galaxies with no recent star formation through wet mergers or accretion have
almost no satellite galaxies fainter than the r-band absolute magnitude of
about Mr =-14. If only early-type satellites are used, the cutoff is at
somewhat brighter magnitude of about Mr =-15. Such a cutoff has not been found
in other nearby satellite galaxy systems hosted by late-type galaxies or those
with merger features. Various physical properties of satellites depend strongly
on the host-centric distance. Our observation indicates that the satellite
galaxy luminosity function is largely determined by the interaction of
satellites with the environment provided by their host, which sheds light on
the missing satellite galaxy problem.
