  We report on the measurement of the two-point correlation function, and the
pairwise peculiar velocity of galaxies in the IRAS PSCz survey. We compute
these statistics first in redshift space, and then obtain the projected
functions which have simple relations to the real-space correlation functions
on the basis of the method developed earlier in analyzing the Las Campanas
Redshift Survey (LCRS) by Jing, Mo, & B\"orner (1998). We find that the real
space two-point correlation function can be fitted to a power law $\xi(r) =
(r_0/r)^{\gamma}$ with $\gamma=1.69$ and $r_0=3.70 \mpc$. The pairwise peculiar
velocity dispersion $\sigma_{12}(r_p)$ is close to $400 \kms$ at $r_p=3\mpc$
and decreases to about $150 \kms$ at $r_p \approx 0.2 \mpc$. These values are
significantly lower than those obtained from the LCRS. In order to understand
the implications of those measurements on the galaxy biasing, we construct mock
samples for a low density spatially-flat cold dark matter model ($\Omega_0 =
0.3$, $\lambda_0=0.7$, $\Gamma=0.2$, $\sigma_8=1$) using a set of
high-resolution N-body simulations. Applying a stronger cluster-underweight
biasing ($\propto M^{-0.25}$) than for the LCRS ($\propto M^{-0.08}$), we are
able to reproduce these observational data, except for the strong decrease of
the pairwise peculiar velocity at small separations. This is qualitatively
ascribed to the different morphological mixture of galaxies in the two
catalogues. Disk-dominated galaxy samples drawn from the theoretically
constructed GIF catalog yield results rather similar to our mock samples with
the simple cluster-underweight biasing.

Astrophysics