Tiny spectral distortions of the isotropic component of the Cosmic Microwave Background are expected at a level of 1 part per million of its maximum brightness, due to processes happening during the hypothetical cosmological inflation phase, 13.7 billion years ago, and later. Anistropic distortions of the spectrum are expected in the directions of the lines of sight crossing clusters of galaxies and filaments of ionized baryons related to the large scale structure of the Universe. The COSMO and OLIMPO instruments, developed by our research group, aim at the detection of these distortions, and require specific analysis methods and models. Here we seek support to develop these tools, which represent essential ingredients of the experiments.
The measurements from OLIMPO mark for the first time the transition from photometric to spectroscopic measurements of the Sunyaev-Zeldovich effect in clusters of galaxies. As discussed in de Bernardis et al. (A&A 538 A86 2012) the main advantage of spectroscopic measurements of the SZ effect is the possibility to separate unambiguously the different components of the SZ signal (thermal, non-thermal, kinematic) from overwhelming foregrounds. These measurements will qualify the DFTS approach used in OLIMPO for its use on the large MILLIMETRON satellite mission of ROSCOSMOS.
The measurements of COSMO promise to go one order of magnitude better than the current upper limits (from COBE-FIRAS) on the isotropic spectral distortions. Will also demonstrate the effectiveness of this instrument design, so that its operation can be replicated on a stratospheric balloon, thus widening significantly the frequency coverage.