1203.2703 (Rachid Ouyed)

A universal, post Big-Bang Nucleo-synthesis, pre-Galactic, origin of the
Lithium (Spite) Plateau    [PDF]

Rachid Ouyed

(Abridged abstract) We investigate the lithium plateau in the context of primordial dual-shock quark novae (dsQNe; i.e. a QN occurring a few days to a few weeks following the preceding SN explosion) going off in the wake of Pop. III stars. The neutron-rich relativistic QN ejecta leads to spallation of 56Ni processed in the ejecta of the preceding SN ejecta and thus to "iron impoverishment" of the primordial gas swept by dsQNe. We show that the generation of stars formed from fragmentation of pristine clouds swept-up by dsQNe acquire a metallicity with -7.5 < [Fe/H] < -1.5 for dsQNe with 2 < t_delay (days) < 30. Spallation in dsQNe naturally lead to the depletion of 56Ni and formation of sub-Ni elements such as Ti, V, Cr, and Mn providing a reasonable account of the trends observed in galactic halo metal-poor stars. CEMP stars with [C/Fe] > 2 (and up to [C/Fe] ~ 5) can be accounted for in our model for dsQNe with t_delay < 5 days (i.e. [Fe/H] < -4). These dsQNe lead to important destruction of 56Ni (and thus to a drastic reduction of the amount of Fe in the swept up cloud) while preserving the C processed in the outer layers of the SN ejecta. NEMP stars are also accounted for in our model. Neutron-capture of the spallated neutrons in the inner SN shell leads to production of s-process elements; CEMP-s and CEMP-r stars can form without involving accretion from a binary companion. Lithium is produced from the interaction of the neutron-rich QN ejecta with the outer (oxygen-rich) layers of the SN ejecta. A 7Li plateau with 2 < A(Li) < 2.4 is naturally produced in our model from dsQNe with t_delay > 10-11 days (i.e. [Fe/H] > -3). For shorter delays the temperature of the SN shell is too hot (> 2.5x10^6 K) for the spallated 7Li to survive. We find a corresponding 6Li plateau with 6Li/7Li < 0.3.

View original: http://arxiv.org/abs/1203.2703