The parameter-free Finger-Of-God model and its application to 21cm
  intensity mapping
  Using the galaxy catalog built from ELUCID N-body simulation and the
semi-analytical galaxy formation model, we have built a mock HI intensity
mapping map. We have implemented the Finger-of-God (FoG) effect in the map by
considering the galaxy HI gas velocity dispersion. By comparing the HI power
spectrum in the redshift space with the measurement from IllustrisTNG
simulation, we have found that such FoG effect can explain the discrepancy
between current mock map built from N-body simulation and Illustris TNG
simulation. Then we built a parameter-free FoG model and a shot-noise model to
calculate the HI power spectrum. We found that our model can accurately fit
both the monopole and quadrupole moments of the HI matter power spectrum. Our
method of building the mock HI intensity map and the parameter-free FoG model
will be widely useful for the up-coming 21cm intensity mapping experiments,
such as CHIME, Tianlai, BINGO, FAST and SKA. It is also crucial for us to study
the non-linear effects in 21cm intensity mapping.
