On detecting CMB spectral distortions: Recombination to Reionization

The ΛCDM model of cosmology predicts inevitable, weak distortions in the spectrum of the Cosmic Microwave Background (CMB) from that of a blackbody. However, no such deviations have been measured to date. I present work on simulating realistic foregrounds which present astrophysical challenges to detect the faint global redshifted 21-cm signal from the Cosmic Dawn and Epoch of Reionization. After discussing a suggested method for foreground separation, I will present ongoing efforts at the Raman Research Institute to detect this faint cosmological signal from space. I will discuss PRATUSH -- the proposed lunar orbiter experiment, which will make scientific measurements in the lunar farside using a custom-designed radiometer. I will also discuss a feasibility study for a ground-based detection of extremely weak, ripple-like additive features in the CMB spectrum created by photons emitted during cosmological recombination (900 < _z_ < 7000). Detection and measurement of these CMB spectral distortions will enable a better understanding of the thermal and ionization history of the Universe and help us probe redshifts that have never been directly observed thus far.