Redshift Distortions and Omega in IRAS Surveys
Abstract
Description
Redshift space distortions on large scales can be used to measure the linear growth rate parameter $\ff \approx Ω^{0.6}/b$. I report here measurements of such distortions in the IRAS 2 Jy, 1.2 Jy, and QDOT redshift surveys, finding $\ff = 0.69^{+ .21}_{- .19}$ from a merged QDOT plus 1.2 Jy catalogue. Unfortunately, confidence in this result is undermined by a marked ($4σ$) change in the pattern of clustering in QDOT beyond about $80 h^{-1} Mpc$. A similar effect may be present at a mild level in the 1.2 Jy survey. The effect may be caused by systematic variation in the effective flux limit of the IRAS PSC over the sky, with a dispersion of $\sim 0.1$ Jy on scales $\sim 7^{\circ}$. If so, then the value of $\ff$ inferred from redshift distortions in IRAS surveys may be systematically underestimated.
13 pages, now including 6 embedded EPS figures. No text change. LaTeX, clustering.sty file included. Invited review, published in ``Clustering in the Universe'', Proc. XXXth Rencontres Moriond, held at Les Arcs, France, 11-18 March 1995, ed. S. Maurogordato, C. Balkowski, C. Tao & J. Tran Thanh Van, Editions Frontieres, pp. 143-155
13 pages, now including 6 embedded EPS figures. No text change. LaTeX, clustering.sty file included. Invited review, published in ``Clustering in the Universe'', Proc. XXXth Rencontres Moriond, held at Les Arcs, France, 11-18 March 1995, ed. S. Maurogordato, C. Balkowski, C. Tao & J. Tran Thanh Van, Editions Frontieres, pp. 143-155