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

Preprint

9 January 2006

preprint
Published by arXiv in arXiv

https://doi.org/10.48550/arXiv.astro-ph/0511698

Abstract

In the context of the ``missing metals problem'', the contributions of the UV-selected z=2.2 ``BX'' galaxies and z=2.5 ``distant red galaxies'' (DRGs) have not been discussed previously. Here we show that: (i) DRGs only make a marginal contribution to the metal budget (~ 5%); (ii) BX galaxies contribute as much as 18% to the metal budget; and (iii) the K-bright subsample ($K2 are a major source of metals in the budget. We showed in the first paper of this series that submm galaxies (SMGs) brighter than 3 mJy contribute ~5% (<9% as an upper limit) to the metal budget. Adding the contribution of SMGs and damped Ly-alpha absorbers, to the contribution of UV selected galaxies, implies that at least 30% of the metals (in galaxies) have been accounted for at z=2. The cosmic metal density thus accounted for is ~ 1.3\times 10^6 \rhosun. This is a lower limit given that galaxies on the faint-end of the luminosity function are not included. An estimate of the distribution of metals in local galaxies as a function luminosity suggests that galaxies with luminosity less than L^{\star}$ contribute about half of the total mass of metals. If the metals in galaxies at z ~ 2 are similarly distributed then faint galaxies alone cannot solve the `missing metals problem.' Galaxy populations at z ~ 2 only account for about 50% of the total metals predicted.

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