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arXiv · 1401.1811

Galactic and Circumgalactic OVI and its Impact on the Cosmological Metal and Baryon Budgets at 2<z<3.5

Nicolas Lehner·John M. O'Meara·Andrew J. Fox·J. Christopher Howk·J. Xavier Prochaska·Vincent Burns·Ashley A. Armstrong
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Abstract

We present the first results from our NASA Keck Observatory Database of Ionized Absorbers toward Quasars (KODIAQ) survey which aims to characterize the properties of the highly ionized gas of high redshift galaxies and their circumgalactic medium (CGM) at 2 1, log N(HI) > 17.3) as probes of these galaxies and their CGM where both transitions of the O VI doublet have little contamination from the Ly {\alpha}, {\beta} forests. We found 20 absorbers that satisfy these rules: 7 Lyman limit systems (LLSs), 8 super-LLSs (SLLSs) and 5 damped Ly{\alpha} (DLAs). The O VI detection rate is 100% for the DLAs, 71% for the LLSs, and 63% for the SLLSs. When O VI is detected, log N(OVI)=14.9+/-0.3, an average O VI column density substantially larger and with a smaller dispersion than found in blind O VI surveys at similar redshifts. Strong O VI absorption is therefore nearly ubiquitous in the CGM of z~2-3 galaxies. The total velocity widths of the O VI profiles are also large (200 1) at 2 1 absorbers could contain as much as 3-14% of the cosmic baryon budget at z~2-3, only second to the Ly{\alpha} forest. We conservatively show that 5-20% of the metals ever produced at z~2-3 are in form of highly ionized metals ejected in the CGM of galaxies.

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Nicolas Lehner, John M. O'Meara, Andrew J. Fox, J. Christopher Howk, J. Xavier Prochaska, Vincent Burns, Ashley A. Armstrong. 2014-01-08. Galactic and Circumgalactic OVI and its Impact on the Cosmological Metal and Baryon Budgets at 2<z<3.5. https://doi.org/10.1088/0004-637x/788/2/119

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