Where are the missing cosmic metals?

The majority of the heavy elements produced by stars 2 billion years after the big bang (redshift z approximate to 3) are presently undetected at those epochs. We propose a solution to this cosmic missing metals problem in which such elements are stored in gaseous halos produced by supernova explosions around star-forming galaxies. By using data from the ESO VLT Large Program, we find that ( 1) only 5% - 9% of the produced metals reside in the cold phase, the rest being found in the hot (T = 10(5.8) - 10(6.4) K) phase, and ( 2) 1% - 6% ( 3% - 30%) of the observed C iv ( O vi) is in the hot phase. We conclude that at z greater than or similar to 3, more than 90% of the metals produced during the star formation history can be placed in a hot phase of the intergalactic medium (IGM), without violating any observational constraint. The observed galaxy mass-metallicity relation and the IGM and intracluster medium metallicity evolution are also naturally explained by this hypothesis.