The redshift-space distortion ( RSD ) in the observed distribution of galaxies is known as a powerful probe of cosmology .
Observations of large-scale RSD , caused by the coherent gravitational infall of galaxies , have given tight constraints on the linear growth rate of the large-scale structures in the universe .
On the other hand , the small-scale RSD , caused by galaxy random motions inside clusters , has not been much used in cosmology , but also has cosmological information because universes with different cosmological parameters have different halo mass functions and virialized velocities .
We focus on the projected correlation function w ( r _ { p } ) and the multipole moments \xi _ { l } on small scales ( 1.4 to 30 h ^ { -1 } Mpc ) .
Using simulated galaxy samples generated from a physically motivated \replaced halo-galaxymost bound particle ( MBP ) -galaxy correspondence scheme in the Multiverse Simulation , we examine the dependence of the small-scale RSD on the cosmological matter density parameter \Omega _ { m } , the satellite velocity bias with respect to MBPs , b _ { v } ^ { s } , and the \replaced merger time scalemerger-time-scale parameter \alpha .
We find that \alpha = 1.5 gives an excellent fit to the w ( r _ { p } ) and \xi _ { l } measured from the SDSS-KIAS value added galaxy catalog .
We also define the “ strength ” of Fingers-of-God as the ratio of the parallel and perpendicular size of the contour in the two-point correlation function set by a specific threshold value and show that the strength parameter helps constraining ( \Omega _ { m } ,b _ { v } ^ { s } , \alpha ) by breaking the degeneracy among them .
The resulting parameter values from all measurements are ( \Omega _ { m } ,b _ { v } ^ { s } ) = ( 0.272 \pm 0.013 , 0.982 \pm 0.040 ) , indicating a slight reduction of satellite galaxy velocity relative to the MBP .
However , considering that the average MBP speed inside haloes is 0.94 times the dark matter velocity dispersion , the main drivers behind the galaxy velocity bias are gravitational interactions , rather than baryonic effects .