On the "Lensing is Low" of BOSS Galaxies
  Recently, Leauthaud et al discovered that the small-scale lensing signal of
Baryon Oscillation Spectroscopic Survey (BOSS) galaxies is up to 40% lower than
predicted by the standard models of the galaxy-halo connections that reproduced
the observed galaxy stellar mass function (SMF) and clustering. We revisit such
"lensing is low" discrepancy by performing a comprehensive Halo Occupation
Distribution (HOD) modelling of the SMF, clustering, and lensing of BOSS LOWZ
and CMASS samples at Planck cosmology. We allow the selection function of
satellite galaxies to vary as a function of stellar mass as well as halo mass.
For centrals we assume their selection to depend only on stellar mass, as
informed by the directly measured detection fraction of the redMaPPer central
galaxies. The best-fitting HOD successfully describes all three observables
without over-predicting the small-scale lensing signal. This indicates that the
model places BOSS galaxies into dark matter halos of the correct halo masses,
thereby eliminating the discrepancy in the one-halo regime where the
signal-to-noise of lensing is the highest. Despite the large uncertainties, the
observed lensing amplitude above 1 Mpc/h remains inconsistent with the
prediction, which is however firmly anchored by the large-scale galaxy bias
measured by clustering at Planck cosmology. Therefore, we demonstrate that the
"lensing is low" discrepancy on scales below 1 Mpc/h can be fully resolved by
accounting for the halo mass dependence of the selection function. Lensing
measurements with improved accuracy is required on large scales to distinguish
between deviations from Planck and non-linear effects from galaxy-halo
connections.
