Astrophys. J. Lett. 815, L8 (2015)

Given that stars form when clouds of dust and gas collapse, the most active star-forming regions are, unavoidably, obscured by dust. Fortunately, dust does not block radio waves, making radio telescopes a powerful probe of massive gas-rich galaxies with intense star formation activity, which many believe are the progenitors of today's large elliptical galaxies. To better understand the history and evolution of these submillimetre (corresponding to radio wavelengths) massive galaxies (SMGs), Hideki Umehata and co-workers have taken advantage of the high resolution of the Atacama Large Millimeter/submillimeter Array in Chile.

The authors focused on a particular region known as SSA22, 11.5 billion light-years away in the constellation Aquarius. They were able to resolve eight SMGs from a background of a huge web of dark matter filaments. Moreover, they showed that these bright galaxies lie at the intersections of the filaments, suggesting that they are located at high concentrations of dark matter. It could be that we are seeing the growth phase of stars and supermassive black holes that lurk in the centre of huge elliptical galaxies.