Spectral Distortion of the CMB by the Cumulative CO Emission from
  Galaxies throughout Cosmic History
  We show that the cumulative CO emission from galaxies throughout cosmic
history distorts the spectrum of the cosmic microwave background (CMB) at a
level that is well above the detection limit of future instruments, such as the
Primordial Inflation Explorer (PIXIE). The modeled CO signal has a prominent
bump in the frequency interval 100-200 GHz, with a characteristic peak
intensity of ~ 2$\times$10$^{-23}$ W m$^{-2}$ Hz$^{-1}$ sr$^{-1}$. Most of the
CO foreground originates from modest redshifts, z ~ 2-5, and needs to be
efficiently removed for more subtle distortions from the earlier universe to be
detected.
