The clustering of warm and cool IRAS galaxies

Abstract

We use a series of statistical techniques to compare the clustering of samples of IRAS galaxies selected on the basis of their far-infrared emission temperature, to see whether a temperature-dependent effect, such as might be produced by interaction-induced star formation, could be responsible for the increase in clustering strength with redshift in the QDOT redshift survey that has been reported by several authors. The temperature-luminosity relation for IRAS galaxies means that warm and cool samples drawn from a flux-limited sample like QDOT will sample quite different volumes of space. To overcome this problem, and to distinguish truly temperature-dependent results from those depending directly on the volume of space sampled, we consider a pair of samples of warmer and cooler galaxies with matched redshift distributions, as well as pairs of samples selected using a simple temperature cut. ...(abstract shortened).... We conclude that that there may be a temperature-dependent component to the observed increase in the clustering strength of QDOT galaxies with redshift, but that it is less important than a sampling effect, which reflects the local cosmography, rather than the physical properties of the galaxies and their environment. We discuss the implications of this work for the use of IRAS galaxies as probes of large-scale structure and for models accounting for their far-infrared emission by interaction-induced star formation.