PRISM (Polarized Radiation Imaging and Spectroscopy Mission): A White Paper on the Ultimate Polarimetric Spectro-Imaging of the Microwave and Far-Infrared Sky

PRISM (Polarized Radiation Imaging and Spectroscopy Mission) was proposed to\nESA in response to the Call for White Papers for the definition of the L2 and\nL3 Missions in the ESA Science Programme. PRISM would have two instruments: (1)\nan imager with a 3.5m mirror (cooled to 4K for high performance in the\nfar-infrared---that is, in the Wien part of the CMB blackbody spectrum), and\n(2) an Fourier Transform Spectrometer (FTS) somewhat like the COBE FIRAS\ninstrument but over three orders of magnitude more sensitive. Highlights of the\nnew science (beyond the obvious target of B-modes from gravity waves generated\nduring inflation) made possible by these two instruments working in tandem\ninclude: (1) the ultimate galaxy cluster survey gathering 10e6 clusters\nextending to large redshift and measuring their peculiar velocities and\ntemperatures (through the kSZ effect and relativistic corrections to the\nclassic y-distortion spectrum, respectively) (2) a detailed investigation into\nthe nature of the cosmic infrared background (CIB) consisting of at present\nunresolved dusty high-z galaxies, where most of the star formation in the\nuniverse took place, (3) searching for distortions from the perfect CMB\nblackbody spectrum, which will probe a large number of otherwise inaccessible\neffects (e.g., energy release through decaying dark matter, the primordial\npower spectrum on very small scales where measurements today are impossible due\nto erasure from Silk damping and contamination from non-linear cascading of\npower from larger length scales). These are but a few of the highlights of the\nnew science that will be made possible with PRISM.\n