Cosmological Signatures in High S:N Spectra

Abstract

We review briefly the observational status of abundance determinations for those elements produced in the first seconds of a “standard” Big Bang Universe, showing that although [4He] and [D] appear not to be mutually compatible there is still room for reconciliation via astration of D, for values consistent with estimated [7Li]. New limits to production cross-sections for 7Li appear to limit Nv (the number of light neutrino types) to no more than 3. Non-standard models with fluctuations are briefly considered; they are attractive because they use Ω = 1 and may also yield early C, N, O in significant quantities. The true value of 7Li [10-9 or 10−10 w.r.t. H] is the critical test here. We show where spectra of improved S:N are needed to progress in constraining cosmological models.