Millimetre background radiation and galaxy formation

Abstract

A simple model of galaxy formation by hierarchical clustering in a cold dark matter universe is used to predict the millimeter background radiation expected from coalescing galaxies. This predicts that the comoving luminosity density produced by star formation increases with redshift as (1 + z) exp 3/2. If star formation occurs in dusty galaxies, our simplest models predict that the millimeter background radiation should have a flat spectrum, I(nu) varies as nu exp 0. The precise spectral measurements of the cosmic background radiation by the COBE satellite enable constraints to be placed upon such models of galaxy and metal formation, and raise the prospect of detecting, by more sensitive observations, the background radiation due to young galaxies. A literal interpretation of the limits suggests that the baryon density parameter is small, with Omega(B) not greater than 2.5 x 10 exp -3/sq h.