A Self-Calibrating Halo-Based Group Finder: Application to SDSS
  We apply a new galaxy group finder to the Main Galaxy Sample of the SDSS.
This algorithm introduces new freedom to assign halos to galaxies that is
self-calibrated by comparing the catalog to complementary data. These include
galaxy clustering data and measurements of the total satellite luminosity from
deep imaging data. We present constraints on the galaxy-halo connection for
star-forming and quiescent populations. The results of the self-calibrated
group catalog differ in several key ways from previous group catalogs and halo
occupation analyses. The transition halo mass scale, where half of halos
contain quiescent central galaxies, is at M_h~10^12.4 Msol/h, significantly
higher than other constraints. Additionally, the width of the transition from
predominantly star-forming halos to quiescent halos occurs over a narrower
range in halo mass. Quiescent central galaxies in low-mass halos are
significantly more massive than star-forming centrals at the same halo mass,
but this difference reverses above the transition halo mass. We find that the
scatter in logM* at fixed M_h is ~0.2 dex for massive halos, in agreement with
previous estimates, but rises sharply at lower halo masses. The halo masses
assigned by the group catalog are in good agreement with weak lensing estimates
for star-forming and quiescent central galaxies. We discuss possible
improvements to the algorithm made clear by this first application to data. The
group catalog is made publicly available.
