The clustering of hot and cold IRAS galaxies: the redshift-space correlation function

We measure the autocorrelation function xi, of galaxies in the IRAS Point Source Catalogue galaxy redshift (PSCz) survey and investigate its dependence on the far-infrared colour and absolute luminosity of the galaxies. We find that the PSCz survey correlation function can be modelled out to a scale of 10 h(-1) Mpc as a power law of slope 1.30 +/-0.04 and correlation length 4.77 +/-0.20. At a scale of 75 h(-1) Mpc we find the value of J(3) to be 1500 +/- 400. We also find that galaxies with higher 100 mum/60 mum flux ratio, corresponding to cooler dust temperatures, are more strongly clustered than warmer galaxies. Splitting the survey into three colour subsamples, we find that, between 1 and 10 h(-1) Mpc, the ratio of xi is a factor of 1.5 higher for the cooler galaxies compared with the hotter galaxies. This is consistent with the suggestion that hotter galaxies have higher star formation rates, and correspond to later-type galaxies which are less clustered than earlier types. Using volume-limited subsamples, we find a weak variation of xi as a function of absolute luminosity, in the sense that more luminous galaxies are less clustered than fainter galaxies. The trend is consistent with the colour dependence of xi and the observed colour-luminosity correlation, but the large uncertainties mean that it has a low statistical significance.