Clustering in the 1.2 Jy IRAS Galaxy Redshift Survey II: Redshift Distortions and ξ(r_p,π)

Karl B Fisher; Marc Davis; Michael A Strauss; Amos Yahil; John P Huchra

doi:10.1093/mnras/267.4.927

paper

Clustering in the 1.2 Jy IRAS Galaxy Redshift Survey II: Redshift Distortions and ξ(r_p,π)

arXiv:astro-ph/9308013 · doi:10.1093/mnras/267.4.927

Abstract

We examine the effect of redshift space distortions on the galaxy two-point correlation function $ξ (r_{p}, π)$ as a function of separations parallel ( $r_{p}$ ) and perpendicular ( $π$ ) to the line of sight. We find that the relative velocity dispersion of pairs of IRAS galaxies is $σ (r) = 31 7_{- 49}^{+ 40}$ \kms at $r=1 \mpc$, consistent with previous estimates derived from optically selected galaxy catalogues. Unfortunately, the use of this result to estimate $Ω$ via the Cosmic Virial Theorem is thwarted by large systematic uncertainties. We also fit for the mean relative streaming velocity of pairs, $v_{12} (r)$ , which describes the growth of fluctuations on both linear and nonlinear scales. We find that $v_{12} (r) = 16 7_{- 67}^{+ 99}$ \kms at $r = 4$ \mpc, so that on average, approximately half the Hubble expansion velocity of pairs at this separation is canceled by infall. At $r = 10$ \mpc, the amplitude of the streaming is lower and $v_{12}(r) = 109^{+64}_{-47} \kms$. Linear perturbation theory then implies that $Ω^{0.6} / b = 0.4 5_{- 0.18}^{+ 0.27}$ on scales $\sim 10-15 \mpc$. The amplitude of $v_{12} (r)$ is sensitive to the assumed shape of $σ (r)$ ; if the latter deviates substantially from a virialized form on small scale, our best fit amplitude of $v_{12} (r)$ can deviate by a factor of two.

28 pages of uuencoded compressed postscript; figures included

Clustering in the 1.2 Jy IRAS Galaxy Redshift Survey II: Redshift Distortions and ξ(r_p,π)

Abstract

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