Origin of cosmic chemical abundances

摘要: Cosmological N-body hydrodynamic computations following atomic and molecular chemistry (e$^-$, H, H$^+$, H$^-$, He, He$^+$, He$^{++}$, D, D$^+$, H$_2$, H$_2^+$, HD, HeH$^+$), gas cooling, star formation production of heavy elements (C, N, O, Ne, Mg, Si, S, Ca, Fe, etc.) from stars covering a range mass metallicity are used to explore the origin several chemical abundance patterns study both metal content during simulated galaxy assembly. The resulting trends show remarkable similarity up-to-date observations most metal-poor damped Lyman-$\alpha$ absorbers at redshift $z\gtrsim 2$. These exhibit transient nature represent collapsing gaseous structures captured while cooling is becoming effective in lowering temperature below $\sim 10^4\,\rm K$, before they disrupted by episodes or tidal effects. Our theoretical results agree with available data for typical elemental ratios, such as [C/O], [Si/Fe], [O/Fe], [Si/O], [Fe/H], [O/H] redshifts $z\sim 2-7$. Correlations between HI H$_2$ abundances temporal local variations large spreads result increasing cosmic activity 6$ 3$. scatter we find ratios compatible observational explained simultaneous enrichment sources different stellar phases belonging populations. Simulated synthetic spectra support existence cold clumps optical depth that could be potential population~III sites low intermediate redshift. expected dust line recent determinations.