Many new and enigmatic high redshift galaxies that are intensively forming stars have been discovered using ESA's Planck and Herschel satellites . These galaxies occur in clumps - and could be the long-sought formation phase of galaxy clusters. Some appear very bright, and have been found to be gravitationally lensed galaxies. These rapidly star-forming galaxies could help solve a central problem in cosmology: how did the large scale structure of galaxies form?
From the standpoint of galaxy evolution, studying the intense star-formation epoch in massive dark-matter halos will provide a wealth of information on the kinematics and evolutionary history of galaxies in massive galaxy clusters. For cosmology, galaxy clusters tell us about the baryon content of the Universe, the role of dark matter in the assembly of large scale structure, and provides insights into possible deviations from our simple, Gaussian, model of the early universe. This means that the search for distant galaxy clusters and/or galaxies amplified by gravitational lensing is a very hot topic. ESA's Planck satellite can find these rare objects over the entire sky, while ESA's Herschel space observatory can scrutinize them in fine detail.
The Planck all-sky observed at 545 GHz (bottom), with black dots indicating the location of our high-redshift candidates, observed by Herschel. The images around show Herschel/SPIRE observations, where contours represent the galaxy density. Dole, Guéry, Hurier, ESA, Planck Collab., HFI consotrium, IAS, CNES, Univ. Paris-Sud, CNRS