The clustering evolution of dusty star-forming galaxies

Abstract

We present predictions for the clustering of galaxies selected by their emission at far-infrared (FIR) and sub-millimetre wavelengths. This includes the first predictions for the effect of clustering biases induced by the coarse angular resolution of single-dish telescopes at these wavelengths. We combine a new version of the galform model of galaxy formation with a self-consistent model for calculating the absorption and re-emission of radiation by interstellar dust. Model galaxies selected at 850μm reside in dark matter haloes of mass Mhalo ~ 1011.5-1012 h-1 M⊙, independent of redshift (for 0.2 ≲ z ≲ 4) or flux (for 0.25 ≲ S850 μm ≲ 4 mJy). At z ~ 2.5, the brightest galaxies (S850 μm > 4 mJy) exhibit a correlation length of r0=5.5-0.5+0.3 h-1 Mpc, consistent with observations. We show that these galaxies have descendants with stellar masses M ~ 1011 h-1 M⊙ occupying haloes spanning a broad range in mass Mhalo ~ 1012-1014 h-1 M⊙. The FIR emissivity at shorter wavelengths (250, 350 and 500 μm) is also dominated by galaxies in the halo mass range Mhalo ~ 1011.5-1012 h-1 M⊙, again independent of redshift (for 0.5 ≲ z ≲ 5). We compare our predictions for the angular power spectrum of cosmic infrared background anisotropies at these wavelengths with observations, finding agreement to within a factor of ~2 over all scales and wavelengths, an improvement over earlier versions of the model. Simulating images at 850 μm, we show that confusion effects boost the measured angular correlation function on all scales by a factor of ~4. This has important consequences, potentially leading to inferred halo masses being overestimated by an order of magnitude.