Deuterium at high redshift: Primordial or evolved?

N. Prantzos (1) , Y. Ishimaru (1)

1 IAP - Institut d'Astrophysique de Paris

On the basis of arguments from galactic chemical evolution we suggest that the recent observations of D/H vs. metallicity in several high redshift absorbers are best understood if the primordial D value is in the range D_P/H ~ 2-3x 10^-5. This range points to a rather high baryonic density (Omega_Bh ²=0.019-0.026) compatible to the one obtained by recent estimates based on the Cosmic Microwave Background (CMB) anisotropy measurements. Slightly higher values (D/H ~ 4x 10^-5) are found in Lyman limit systems. Such values are still compatible with CMB estimates but, if taken at face value, suggest a trend of decreasing D abundance with metallicity. We argue that special assumptions, like differential enrichment, are required to explain the data in that case. A clear test of such a differential enrichment would be an excess of products of low mass stars like C and/or N in those systems, but currently available data of N/Si in DLAs do not favour such a ``non-standard'' scenario.

Mots clés: COSMOLOGY; GALAXIES: ABUNDANCES; GALAXIES: EVOLUTION; Astrophysics

Domaines: Planète et Univers [physics]

N. Prantzos, Y. Ishimaru. Deuterium at high redshift: Primordial or evolved?. Astronomy and Astrophysics - A&A, 2001, 376, pp.751-755. ⟨10.1051/0004-6361:20010861⟩. ⟨hal-04110943⟩