The Completed SDSS-IV extended Baryon Oscillation Spectroscopic Survey:
  exploring the Halo Occupation Distribution model for Emission Line Galaxies
  We study the modelling of the Halo Occupation Distribution (HOD) for the
eBOSS DR16 Emission Line Galaxies (ELGs). Motivated by previous theoretical and
observational studies, we consider different physical effects that can change
how ELGs populate haloes. We explore the shape of the average HOD, the fraction
of satellite galaxies, their probability distribution function (PDF), and their
density and velocity profiles. Our baseline HOD shape was fitted to a
semi-analytical model of galaxy formation and evolution, with a decaying
occupation of central ELGs at high halo masses. We consider Poisson and
sub/super-Poissonian PDFs for satellite assignment. We model both NFW and
particle profiles for satellite positions, also allowing for decreased
concentrations. We model velocities with the virial theorem and particle
velocity distributions. Additionally, we introduce a velocity bias and a net
infall velocity. We study how these choices impact the clustering statistics
while keeping the number density and bias fixed to that from eBOSS ELGs. The
projected correlation function, $w_p$, captures most of the effects from the
PDF and satellites profile. The quadrupole, $\xi_2$, captures most of the
effects coming from the velocity profile. We find that the impact of the mean
HOD shape is subdominant relative to the rest of choices. We fit the clustering
of the eBOSS DR16 ELG data under different combinations of the above
assumptions. The catalogues presented here have been analysed in companion
papers, showing that eBOSS RSD+BAO measurements are insensitive to the details
of galaxy physics considered here. These catalogues are made publicly
available.
