Where Are the Missing Cosmic Metals?

The majority of the heavy elements produced by stars 2 billion years afterthe Big Bang (redshift z~3) are presently undetected at those epochs. Wepropose a solution to this cosmic `missing metals' problem in which suchelements are stored in gaseous halos produced by supernova explosions aroundstar-forming galaxies. By using data from the ESO/VLT Large Program, we findthat:(i) only 5%-9% of the produced metals reside in the cold phase, the restbeing found in the hot (log T=5.8-6.4) phase; (ii) 1%-6% (3%-30%) of theobserved CIV (OVI) is in the hot phase. We conclude that at z~3 more than 90%of the metals produced during the star forming history can be placed in a hotphase of the IGM, without violating any observational constraint. The observedgalaxy mass-metallicity relation, and the intergalactic medium and intraclustermedium metallicity evolution are also naturally explained by this hypothesis.Comment: 9 pages, 2 figures, ApJ Letters, in pres