We present predictions for the clustering of galaxies selected by their emission at far infra-red ( 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 850 \mu m reside in dark matter halos of mass M _ { halo } \sim 10 ^ { 11.5 } -10 ^ { 12 } h ^ { -1 } M _ { \odot } , independent of redshift ( for 0.2 \lesssim z \lesssim 4 ) or flux ( for 0.25 \lesssim S _ { 850 \mu m } \lesssim 4 mJy ) .
At z \sim 2.5 , the brightest galaxies ( S _ { 850 \mu m } > 4 mJy ) exhibit a correlation length of r _ { 0 } = 5.5 _ { -0.5 } ^ { +0.3 } h ^ { -1 } Mpc , consistent with observations .
We show that these galaxies have descendants with stellar masses M _ { \star } \sim 10 ^ { 11 } h ^ { -1 } M _ { \odot } occupying halos spanning a broad range in mass M _ { halo } \sim 10 ^ { 12 } -10 ^ { 14 } h ^ { -1 } M _ { \odot } .
The FIR emissivity at shorter wavelengths ( 250 , 350 and 500 \mu m ) is also dominated by galaxies in the halo mass range M _ { halo } \sim 10 ^ { 11.5 } -10 ^ { 12 } h ^ { -1 } M _ { \odot } , again independent of redshift ( for 0.5 \lesssim z \lesssim 5 ) .
We compare our predictions for the angular power spectrum of cosmic infra-red background anisotropies at these wavelengths with observations , finding agreement to within a factor of \sim 2 over all scales and wavelengths , an improvement over earlier versions of the model .
Simulating images at 850 \mu m , we show that confusion effects boost the measured angular correlation function on all scales by a factor of \sim 4 .
This has important consequences , potentially leading to inferred halo masses being overestimated by an order of magnitude .