Exploring Cosmic Origins with CORE: Extragalactic sources in Cosmic Microwave Background maps

Abstract

We update and extend our earlier discussion of the potential of a next generation space-borne CMB experiment for studies of extragalactic sources. Our analysis has particular bearing on the definition of a future space project, CORE, that will be submitted in response to ESA's call for a Medium-size mission opportunity (M5) as the successor of the Planck satellite. Even though the effective telescope size will be similar or somewhat smaller than that of Planck, CORE will have a considerably better angular resolution at its highest frequencies, since, at variance with Planck, it will be diffraction limited. The better resolution implies a substantial decrease of the source confusion, i.e. substantially fainter detection limits. In particular, CORE will detect several thousands of strongly lensed high-z galaxies distributed over the full sky. These are the brightest (sub-)mm sources in the sky and, as such, will allow studies of high-z star forming galaxies in exquisite detail. Also, the CORE resolution matches the typical sizes of high-z galaxy proto-clusters much better than the Planck resolution, resulting in a much higher detection efficiency. These objects will be caught in an evolutionary phase beyond the reach of surveys in other wavebands. Furthermore, CORE will provide unique information on the evolution of the star formation in virialized groups and clusters of galaxies up to the highest possible redshifts. Finally, thanks to its very high sensitivity, CORE will detect the polarized emission of thousands of radio sources in a poorly explored frequency range, and, for the first time, of dusty galaxies.