2024/03/04 by Sameer Sameer, Nicolas Lehner, Sameer +9
Engineering · Physics and Astronomy · #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Metallurgical Processes and Thermodynamics #Nuclear Physics and Applications
paper · pdf · doi:10.48550/arxiv.2403.02374
openalex publication_date 2024/03/04 · openalex created_date 2024/03/07 · openalex updated_date 2026/07/28
We analyze the \ovi content and kinematics for 126 \hi-selected absorbers at 0.14 \lesssim z \lesssim 0.73 for which the metallicities of their cool photoionized phase have been determined. We separate the absorbers into 100 strong \lya forest systems (SLFSs with 15 \la \colden < 16.2) and 26 partial Lyman Limit systems (pLLSs with 16.2≤ \colden ≤ 17.2). The sample is drawn from the COS CGM Compendium (CCC) and has \ovi coverage in \sn ≥ 8 \it HST/COS G130M/G160M QSO spectra, yielding a 2σ completeness level of \coldenovi ≥ 13.6. The \ovi detection rates differ substantially between low-metallicity (LM; \xh ≤ -1.4) and high-metallicity (HM; \xh > -1.4) SLFSs, with 20% and 60% detection rates, respectively. The \ovi detection frequency for the HM and LM pLLSs is, however, similar at ∼60%. The SLFSs and pLLSs without detected \ovi are consistent with the absorbing gas being in a single phase, while those with \ovi trace multiphase gas. We show that the \ovi velocity widths and column densities have different distributions in LM and HM gas. We find a strong correlation between \ovi column density and metallicity. The strongest (\coldenovi \ga 14) and broadest \ovi absorbers are nearly always associated with HM absorbers, while weaker \ovi absorbers are found in both LM and HM absorbers. From comparisons with galaxy-selected and blind \ovi surveys, we conclude absorbers with \coldenovi \ga 14 most likely arise in the circumgalactic medium (CGM) of star-forming galaxies. Absorbers with weak \ovi likely trace the extended CGM or intergalactic medium (IGM), while those without \ovi likely originate in the IGM.