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arXiv · 1808.05252

The COS CGM Compendium (CCC). I: Survey Design and Initial Results

Nicolas Lehner·Christopher B. Wotta·J. Christopher Howk·John M. O'Meara·Benjamin D. Oppenheimer·Kathy L. Cooksey
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Abstract

We present a neutral hydrogen-selected absorption-line survey of gas with HI column densities 15 2 orders of magnitude at any given N(HI), indicating a wide range of metallicities (from solar to <1/100 solar). In the range 16.2<log N(HI)<17, there is a gap in the N(MgII) distribution corresponding to gas with ~10% solar metallicity, consistent with the gap seen in the previously identified bimodal metallicity distribution in this column density regime. Less than 3% of the absorbers in our sample show no detectable metal absorption, implying truly-pristine gas at z<1 is uncommon. We find [FeII/MgII] = -0.4+/-0.3, and since alpha-enhancement can affect this ratio, dust depletion is extremely mild.

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Nicolas Lehner, Christopher B. Wotta, J. Christopher Howk, John M. O'Meara, Benjamin D. Oppenheimer, Kathy L. Cooksey. 2018-08-15. The COS CGM Compendium (CCC). I: Survey Design and Initial Results. https://doi.org/10.3847/1538-4357/aadd03

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