The cosmic submillimeter background - A signature of the initial burst of galaxy formation?

Abstract

We propose a heuristic model for the origin of the cosmic submillimeter background (SMB), reported by the Nagoya-Berkeley collaboration. The SMB is interpreted as a direct signature of an epoch of (initial) galaxy formation at z_(gf) ~ 10 - 15. The sources of the SMB are proposed to be dust-shrouded starburst protogalaxies, similar to the luminous IRAS galaxies at low redshifts. We interpret them as the progenitors of old stellar populations at low redshifts, ellipticals, bulges, and stellar components of the halos. The largest allowed time scales for the star formation in these models are in the range FWHM ~ 0.2 - 0.6 Gyr, for Ω _0 = 0.1; for Ω _0 = 1, the allowed widths are about a factor of two lower. In order not to overproduce the baryonic mass density, it is necessary that the IMF in these starbursts is biased towards high-mass stars; however, a substantial range in the IMF parameters is allowed. This postulated population of protogalaxies may be an important contributor to the diffuse soft x-ray background. The predicted surface density of protogalaxies would be in the range ~10-100 arcsec^(-2), which is consistent with all relevant anisotropy measurements available at this time.