What size haloes do local LIRGs live in?

Abstract

This work investigates the preferred environment of local luminous IR galaxies (LIRGs) in terms of the host haloes that they inhabit, and in comparison to a control galaxy sample. The LIRGs are drawn from the IRAS Point Source Catalogue redshift survey (PSCz), while the control sample is drawn from the 2MASS redshift survey (2MRS). A Friends-of-Friends algorithm was run on the 2MRS sample to identify galaxies living in the same dark matter haloes and the PSCz galaxies were then associated with these identified haloes. We show that the relative probability of finding local LIRGs with respect to 2MASS galaxies is largest in approximately group size haloes (Mhalo ̃ 1013⊙), and declines both in the cluster regime and in smaller haloes. This confirms, using a different technique than in previous work, that local LIRGs are indeed more abundant in group environments than elsewhere. We also find a trend between the LIR values of LIRGs and their location within their host dark matter haloes, such that the average location of LIRGs with high IR luminosity is closer to the halo centre than for low IR luminosity galaxies. Moreover, this trend does not seem to depend on halo mass. © 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.