Challenges and prospects for better measurements of the CMB intensity spectrum

Abstract

Spectral distortions of the Cosmic Microwave Background (CMB) offer the possibility of probing processes which occurred during the evolution of our Universe going back up to Z$\simeq 10^7$. Unfortunately all the attempts so far carried out for detecting distortions failed. All of them were based on comparisons among absolute measurements of the CMB temperature at different frequencies. We suggest a different approach: measurements of the frequency derivative of the CMB temperature over large frequency intervals instead of observations of the absolute temperature at few, well separated, frequencies as frequently done in the past, and, direct measurements of the foregrounds which hinder bobservations, at the same site and with the same radiometer prepared for the search of CMB distortions. We discuss therefore the perspectives of new observations in the next years from the ground, at very special sites, or in space as independent missions or part of other CMB projects

in extenso version of the invited talk presented at CMB@50, Princeton 9-12 June 2015 19 pages, 4 figures, 2 tables

References in corpus (5)

• Planck intermediate results. XXII. Frequency dependence of thermal emission from Galactic dust in intensity and polarization
• The contribution of the Unresolved Extragalactic Radio Sources to the Brightness Temperature of the sky
• TRIS II: search for CMB spectral distortions at 0.60, 0.82 and 2.5 GHz
• Another look to distortions of the CMB spectrum
• TRIS III: the diffuse galactic radio emission at $\delta =+42^{\circ }$

Cited by in corpus (2)

• Probing large-scale magnetism with the Cosmic Microwave Background
• FSD: Frequency Space Differential measurement of CMB spectral distortions