Cosmological Distortions in Redshift Space
**Previous
abstract** **Next
abstract**

**Session 26 -- The Dynamics of Large Scale Structure**
*Oral presentation, Tuesday, June 13, 1995, 8:30am - 12:30pm*

## [26.04] Cosmological Distortions in Redshift Space

*Barbara S. Ryden (OSU)*
The long-sought value of $q_0$, the deceleration parameter, remains
elusive. One method of finding $q_0$ is to measure the distortions
of large scale structure in redshift space. If the Hubble constant
changes with time, then the mapping between redshift space and
real space is nonlinear, even in the absence of peculiar motions.
When $q_0 > -1$, structures in redshift space will be distorted
along the line of sight; the distortion is proportional to
$(1 + q_0 ) z$ in the limit that the redshift $z$ is small.
The cosmological distortions at $z \le 0.2$ can be found
by measuring the shapes of voids in redshift surveys of galaxies
(such as the upcoming Sloane Digital Sky Survey). The cosmological
distortions are masked to some extent by the distortions caused
by small-scale peculiar velocities; it is difficult to measure the
shape of a void when the fingers of God are poking into it.
The cosmological distortions at $z \sim 1$ can be found by
measuring the correlation function of quasars as a function
of redshift and of angle relative to the line of sight.
Finding $q_0$ by measuring distortions in redshift space, like
the classical methods of determining $q_0$, is simple and elegant in
principle but complicated and messy in practice.

**Tuesday
program listing**