How much dark matter is needed to trigger a starburst in the cosmic cribs where galaxies are born? A new study, based on data from ESA's Herschel Space Observatory, has revealed that dark matter halos with a mass larger than 300 billion times the Sun's are particularly efficient at igniting massive starbursts, as they house the most active star-forming galaxies in the Universe. Astronomers have discovered this key threshold by measuring small fluctuations in the Cosmic Infrared Background, the integrated diffuse emission produced by the dust from every galaxy that ever existed. These fluctuations trace the distribution of otherwise mostly unresolved star-forming galaxies and of the dark matter halos that enshroud them. These results are reported in the 24 February 2011 issue of Nature and are published online.
The distribution of the dark matter, obtained from a numerical simulation, at a redshift z~2, or when the Universe was about 3 billion years old. Credit: From Amblard, Cooray, Serra et al., Nature, 2011