A partial Lyman limit system tracing intragroup gas at z ≈ 0.8 towards HE 1003 + 0149. Issue 1 (12th May 2021)

• Record Type: Journal Article
• Authors: Narayanan, Anand; , Sameer; Muzahid, Sowgat; Johnson, Sean D; Udhwani, Purvi; Charlton, Jane C; Mauerhofer, Valentin; Schaye, Joop; Yadav, Mathin
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 505:Issue 1(2021)
• Page Start: 738
• Page End: 754
• Publication Date: 2021-05-12
• Subjects: galaxies: groups: general -- galaxies: haloes -- intergalactic medium -- quasars: absorption lines; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stab1315
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: 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 * ∼ 10 8 –10 9 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 ∼ 10 4 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.