| Autor: |
Narayanan, Anand, Sameer, Muzahid, Sowgat, Johnson, Sean D, Udhwani, Purvi, Charlton, Jane C, Mauerhofer, Valentin, Schaye, Joop, Yadav, Mathin |
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| Zdroj: |
Monthly Notices of the Royal Astronomical Society; Jul2021, Vol. 505 Issue 1, p738-754, 17p |
| Abstrakt: |
We present analysis of the galaxy environment and physical properties of a partial Lyman limit system at z = 0.83718 with H i and metal-line components closely separated in redshift space (|Δ v | ≈ 400 km s−1) towards the background quasar HE 1003 + 0149. The HST /COS far-ultraviolet spectrum provides coverage of lines of oxygen ions from O i to O v. Comparison of observed spectral lines with synthetic profiles generated from Bayesian ionization modelling reveals the presence of two distinct gas phases in the absorbing medium. The low-ionization phase of the absorber has sub-solar metallicities (∼1/10 solar) with indications of [C/O] <0 in each of three components. The O iv and O v trace a more diffuse higher ionization medium with predicted H i column densities that are ≈2 dex lower. The quasar field observed with VLT /MUSE reveals three dwarf galaxies with stellar masses of M * ∼ 108–109 M⊙, and with star formation rates of ≈0.5–1 M⊙ yr−1, at projected separations of ρ/ R vir ≈ 1.8–3.0 from the absorber. Over a wider field with projected proper separation of ≤5 Mpc and radial velocity offset of |Δ v | ≤ 1000 km s−1 from the absorber, 21 more galaxies are identified in the VLT /VIMOS and Magellan deep galaxy redshift surveys, with 8 of them within 1 Mpc and 500 km s−1, consistent with the line of sight penetrating a group of galaxies. The absorber presumably traces multiple phases of cool (T ∼ 104 K) photoionized intragroup medium. The inferred [C/O] <0 hint at preferential enrichment from core-collapse supernovae, with such gas displaced from one or more of the nearby galaxies, and confined to the group medium. [ABSTRACT FROM AUTHOR] |
| Databáze: |
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