Oxygen pumping II: Probing the Inhomogeneous Metal Enrichment at the Epoch of Reionization with High Frequency CMB Observations

摘要

At the epoch of reionization, when the high-redshift inter-galactic medium(IGM) is being enriched with metals, the 63.2 micron fine structure line of OIis pumped by the ~ 1300 AA soft UV background and introduces a spectraldistortion in the Cosmic Microwave Background (CMB). Here we use a toy modelfor the spatial distribution of neutral oxygen, assuming metal bubbles surrounddark matter halos, and compute the fluctuations of this distortion, and theangular power spectrum it imprints on the CMB. We discuss the dependence of thepower spectrum on the velocity of the winds polluting the IGM with metals, theminimum mass of the halos producing these winds, and on the cosmic epoch whenthe OI pumping occurs. We find that, although the clustering signal of the CMBdistortion is weak \delta y_{rms} ~ 10^{-7} (roughly corresponding to atemperature anisotropy of few nK), it may be reachable in deep integrationswith high-sensitivity infrared detectors. Even without a detection, theseinstruments should be able to useful constraints on the heavy elementenrichment history of the IGM.