Model BOSS & eBOSS Luminous Red Galaxies at 0.2 < z < 1.0 using SubHalo
  Abundance Matching with 3 parameters
  SubHalo Abundance Matching (SHAM) is an empirical method for constructing
galaxy catalogues based on high-resolution $N$-body simulations. We apply SHAM
on the UNIT simulation to simulate SDSS BOSS/eBOSS Luminous Red Galaxies (LRGs)
within a wide redshift range of $0.2 < z < 1.0$. Besides the typical SHAM
scatter parameter $\sigma$, we include $v_{\rm smear}$ and $V_{\rm ceil}$ to
take into account the redshift uncertainty and the galaxy incompleteness
respectively. These two additional parameters are critical for reproducing the
observed 2PCF multipoles on 5--25$\,h^{-1}\,{\rm Mpc}$. The redshift
uncertainties obtained from the best-fitting $v_{\rm smear}$ agree with those
measured from repeat observations for all SDSS LRGs except for the LOWZ sample.
We explore several potential systematics but none of them can explain the
discrepancy found in LOWZ. Our explanation is that the LOWZ galaxies might
contain another type of galaxies which needs to be treated differently. The
evolution of the measured $\sigma$ and $V_{\rm ceil}$ also reveals that the
incompleteness of eBOSS galaxies decreases with the redshift. This is the
consequence of the magnitude lower limit applied in eBOSS LRG target selection.
Our SHAM also set upper limits for the intrinsic scatter of the galaxy--halo
relation given a complete galaxy sample: $\sigma_{\rm int}<0.31$ for LOWZ at
$0.2<z<0.33$, $\sigma_{\rm int}<0.36$ for LOWZ at $0.33<z<0.43$, and
$\sigma_{\rm int}<0.46$ for CMASS at $0.43<z<0.51$. The projected 2PCFs of our
SHAM galaxies also agree with the observational ones on the 2PCF fitting range.
