The missing metals problem -: II.: How many metals are in z≃2.2 galaxies?

In the context of the 'missing metals problem', the contributions of the ultraviolet-selected z similar or equal to 2.2 'BX' galaxies and z similar or equal to 2.5 'distant red galaxies' (DRGs) have not been discussed previously. Here we show that: (i) DRGs make only a marginal contribution to the metal budget (similar to 5 per cent); (ii) BX galaxies contribute as much as 18 per cent to the metal budget; and (iii) the K-bright subsample (K < 20) of the BX sample (roughly equivalent to the 'BzK' selected samples) contributes roughly half of this 18 per cent, owing to both their larger stellar masses and higher metallicities, implying that the rare K-bright galaxies at z > 2 are a major source of metals in the budget. We showed in the first paper of this series that submillimetre galaxies (SMGs) brighter than 3 mJy contribute similar to 5 per cent (less than or similar to 9 per cent as an upper limit) to the metal budget. Adding the contribution of SMGs and damped Ly alpha absorbers to the contribution of ultraviolet-selected galaxies implies that at least 30 per cent of the metals ( in galaxies) have been accounted for at z similar or equal to 2. The cosmic metal density thus accounted for is rho(Z, galaxies) similar or equal to 1.3 x 10(6) M circle dot Mpc(-3) or, in terms of the closure density, Omega(Z) = 9.6 x 10(-6). This is a lower limit given that galaxies on the faint end of the luminosity function are not included. An estimate of the distribution of metals in local galaxies as a function of luminosity suggests that galaxies with luminosity < L-star contribute about half of the total mass of metals. If the metals in galaxies at z similar to 2 are similarly distributed then faint galaxies alone cannot solve the 'missing metals problem'. Galaxy populations at z similar to 2 account for only about 50 per cent of the total metals predicted.