Multi-wavelength mock galaxy catalogs of the low-redshift Universe
  We present a new suite of mock galaxy catalogs mimicking the low-redshift
Universe, based on an updated halo occupation distribution (HOD) model and a
scaling relation between optical properties and the neutral hydrogen (HI)
content of galaxies. Our algorithm is constrained by observations of the
luminosity function and luminosity- and colour-dependent clustering of SDSS
galaxies, as well as the HI mass function and HI-dependent clustering of
massive HI-selected galaxies in the ALFALFA survey. Mock central and satellite
galaxies with realistic values of $r$-band luminosity, $g-r$ and $u-r$ colour,
stellar mass and HI mass are populated in an $N$-body simulation, inheriting a
number of properties of the density and tidal environment of their host halos.
The host halo of each central galaxy is also `baryonified' with realistic
spatial distributions of stars as well as hot and cold gas, along with the
corresponding rotation curve. Our default HOD assumes that galaxy properties
are a function of group halo mass alone, and can optionally include effects
such as galactic conformity and colour-dependent galaxy assembly bias. The
mocks predict the relation between the stellar mass and HI mass of massive HI
galaxies, as well as the 2-point cross-correlation function of spatially
co-located optical and HI-selected samples. They enable novel null tests for
galaxy assembly bias, provide predictions for the HI velocity width function,
and clarify the origin and universality of the radial acceleration relation in
the $\Lambda$CDM framework.
