High-ion absorption in the proximate damped Lyman-alpha system toward Q0841+129

Abstract

We present VLT/UVES spectroscopy of the quasar Q0841+129, whose spectrum shows a proximate damped Lyman-alpha (PDLA) absorber at z=2.47621 and a proximate sub-DLA at z=2.50620, both lying close in redshift to the QSO itself at z_em=2.49510+/-0.00003. This fortuitous arrangement, with the sub-DLA acting as a filter that hardens the QSO's ionizing radiation field, allows us to model the ionization level in the foreground PDLA, and provides an interesting case-study on the origin of the high-ion absorption lines Si IV, C IV, and O VI in DLAs. The high ions in the PDLA show at least five components spanning a total velocity extent of ~160 km/s, whereas the low ions exist predominantly in a single component spanning just 30 km/s. We examine various models for the origin of the high ions. Both photoionization and turbulent mixing layer models are fairly successful at reproducing the observed ionic ratios after correcting for the non-solar relative abundance pattern, though neither model can explain all five components. We show that the turbulent mixing layer model, in which the high ions trace the interfaces between the cool PDLA gas and a hotter phase of shock-heated plasma, can explain the average high-ion ratios measured in a larger sample of 12 DLAs.

12 pages, 7 figures, accepted for publication in Astronomy and Astrophysics

References in corpus (20)

• A New Calculation of the Ionizing Background Spectrum and the Effects of HeII Reionization
• Time-Dependent Ionization in Radiatively Cooling Gas
• Velocity-Metallicity Correlation for high-z DLA Galaxies: Evidence for a Mass-Metallicity Relation?
• C, N, O Abundances in the Most Metal-Poor Damped Lyman alpha Systems
• X-ray coronae in simulations of disc galaxy formation
• An unbiased measurement of the UV background and its evolution via the proximity effect in quasar spectra
• Hot Halos around High Redshift Protogalaxies: Observations of O VI and N V Absorption in Damped Lyman Alpha systems
• Numerical Study of Turbulent Mixing Layers with Non-Equilibrium Ionization Calculations
• C IV absorption in damped and sub-damped Lyman-alpha systems: correlations with metallicity and implications for galactic winds at z~2-3
• The Role of Sub-damped Lyman-alpha Absorbers in the Cosmic Evolution of Metals
• The SDSS-DR5 Survey for Proximate Damped Lya Systems
• Simulations of High-Velocity Clouds. I. Hydrodynamics and High-Velocity High Ions
• The Nitrogen and Oxygen abundances in the neutral gas at high redshift
• Fundamental Properties of the Highly Ionized Plasmas in the Milky Way
• MHD Turbulent Mixing Layers: Equilibrium Cooling Models
• The Sightline to Q2343-BX415: Clues to Galaxy Formation in a Quasar Environment
• The Surprisingly Constant Strength of O VI Absorbers over Cosmic Time
• Probing feedback in protogalaxies: Multiphase gas in a DLA at z~2.4
• Multiphase Plasma in Sub-Damped Lyman Alpha Systems: A Hidden Metal Reservoir
• Metallicities and dust content of proximate damped Lyman alpha systems in the Sloan Digital Sky Survey

Cited by in corpus (7)

• The ESO UVES Advanced Data Products Quasar Sample - II. Cosmological Evolution of the Neutral Gas Mass Density
• Observed Faraday Effects in Damped Lyman-Alpha Absorbers and Lyman Limit Systems: The Magnetised Environment of Galactic Building Blocks at Redshift=2
• Tentative Detection of the Circumgalactic Medium of the Isolated Low-Mass Dwarf Galaxy WLM
• VLT/UVES observations of peculiar alpha abundances in a sub-DLA at z ~ 1.8 towards the quasar B1101-26
• Extremely broad Lyman-alpha line emission from the molecular intra-group medium in Stephan's Quintet: evidence for a turbulent cascade in a highly clumpy multi-phase medium?
• A high-redshift quasar absorber without CIV - a galactic outflow caught in the act?
• High-resolution observations of two OVI absorbers at z=2 towards PKS 1448-232