The clustering of IRAS galaxies

We investigate the clustering of galaxies in the QDOT redshift survey of IRASgalaxies. We find that the redshift space two-point correlation function iswell approximated by a power-law of slope -1.11+\-0.09, with clustering length3.87+\-0.32 Mpc/h out to pair separations of 25 Mpc\h. On scales larger than 40Mpc/h, the correlation function is consistent with zero. The r.m.s. fluctuationin the count of QDOT galaxies above the Poisson level in spheres of radius 8Mpc/h is \sigma_8^{IRAS}=0.58+\-0.14, showing that fluctuations in thedistribution of IRAS galaxies on these scales are smaller than those of opticalgalaxies by a factor of about 0.65, with an uncertainty of 25%. We find nodetectable difference between the correlation functions measured in redshiftspace and in real space, leading to a $2\sigma$ limit of b_{IRAS}/\Omega^{0.6}>1.05, where b_{IRAS} is the bias factor for IRAS galaxies and \Omega is thecosmological density parameter. The QDOT autocorrelation function calculated inconcentric shells increases significantly with shell radius. This difference ismore likely due to sampling fluctuations than to an increase of the clusteringstrength with galaxy luminosity, but the two effects are difficult todisentangle; our data allow at most an increase of \sim 20% in clusteringstrength for each decade in luminosity. For separations greater than \sim 3Mpc/h, the cross-correlation function of Abell clusters (with Richness R\ge 1)and QDOT galaxies is well approximated by a power-law of slope -1.81+\-0.10,with clustering length 10.10+\-0.45 Mpc/h, and no significant signal beyond\gsim 50 Mpc\h. This cross-correlation depends only weakly on cluster richness.Comment: TeX file. Send email for Figures. MNRAS in pres