English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We present the elemental abundance and H2 content measurements of a DampedLyman-{\alpha} (DLA) system with an extremely large H i column density, log N(Hi) (cm-2) = 22.0+/-0.10, at zabs = 3.287 towards the QSO SDSS J 081634+144612.We measure column densities of H2, C i, C i^*, Zn ii, Fe ii, Cr ii, Ni ii andSi ii from a high signal-to-noise and high spectral resolution VLT-UVESspectrum. The overall metallicity of the system is [Zn/H] = -1.10 +/- 0.10relative to solar. Two molecular hydrogen absorption components are seen at z =3.28667 and 3.28742 (a velocity separation of \approx 52 km s-1) in rotationallevels up to J = 3. We derive a total H2 column density of log N(H2) (cm-2) =18.66 and a mean molecular fraction of f = 2N(H2)/[2N(H2) + N(H i)] =10-3.04+/-0.37, typical of known H2-bearing DLA systems. From the observedabundance ratios we conclude that dust is present in the Interstellar Medium(ISM) of this galaxy, with a enhanced abundance in the H2-bearing clouds.However, the total amount of dust along the line of sight is not large and doesnot produce any significant reddening of the background QSO. The physicalconditions in the H2-bearing clouds are constrained directly from the columndensities of H2 in different rotational levels, C i and C i^* . The kinetictemperature is found to be T = 75 K and the particle density lies in the rangenH = 50-80 cm-3 . The neutral hydrogen column density of this DLA is similar tothe mean H i column density of DLAs observed at the redshift of {\gamma}-raybursts (GRBs). We explore the relationship between GRB-DLAs and high columndensity end of QSO-DLAs finding that the properties (metallicity and depletion)of DLAs with log N(H i) > 21.5 in the two populations do not appear to besignificantly different.

Metallicities, dust and molecular content of a QSO-Damped Lyman-{\alpha} system reaching log N (H i) = 22: An analog to GRB-DLAs