Submillimetre galaxies reside in dark matter haloes with masses greater than 3 × 10 11 solar masses

Galaxies in the background The optically faint 'submillimetre' star-forming galaxies that produce the extragalactic background light at far-infrared wavelengths are challenging to study individually, but their average properties can be determined using statistics such as the angular power spectrum of the background intensity variations. Using this technique, Amblard et al . have observed excess clustering over the linear prediction at arcminute angular scales in the power spectrum of brightness fluctuations at 250, 350 and 500 micrometres. This suggests that submillimetre galaxies are located in dark matter haloes with masses greater than 300 billion times that of the Sun, a direct measurement that will add useful detail to improve theoretical models of galaxy formation and evolution.