Numerical Study of Turbulent Mixing Layers with Non-Equilibrium Ionization Calculations

Abstract

Highly ionized species such as C IV, N V, and O VI, are commonly observed in diffuse gas in various places in the universe, such as in our Galaxy's disk and halo, high velocity clouds (HVCs), external galaxies, and the intergalactic medium. One possible mechanism for producing high ions is turbulent mixing of cool gas with hotter gas in locations where these gases slide past each other. By using hydrodynamic simulations with radiative cooling and non-equilibrium ionization (NEI) calculations, we investigate the physical properties of turbulent mixing layers and the production of high ions. We find that most of the mixing occurs on the hot side of the hot/cool interface and that the mixed region separates into a tepid zone containing radiatively cooled, C IV-rich gas and a hotter zone which is rich in C IV, N V, and O VI. Mixing occurs faster than ionization or recombination, making the mixed gas a better source of C IV, N V, and O VI in our NEI simulations than in our collisional ionization equilibrium (CIE) simulations. In addition, the gas radiatively cools faster than the ions recombine, which also allows large numbers of high ions to linger in the NEI simulations. For these reasons, our NEI calculations predict more high ions than our CIE calculations predict. We also simulate various initial configurations of turbulent mixing layers and discuss their results. We compare the results of our simulations with observations and other models, including other turbulent mixing calculations. The ratios of C IV to N V and N V to O VI are in reasonable agreement with the averages calculated from observations of the halo. There is a great deal of variation from sightline to sightline and with time in our simulations. Such spatial and temporal variation may explain some of the variation seen among observations.

19 pages, 7 figures, 8 tables, Accepted for publication by ApJ

References in corpus (39)

• The 'Forbidden' Abundance of Oxygen in the Sun
• Highly-Ionized High-Velocity Gas in the Vicinity of the Galaxy
• A Reappraisal of the Solar Photospheric C/O Ratio
• Time-Dependent Ionization in Radiatively Cooling Gas
• A High-Resolution Survey of Low-Redshift QSO Absorption Lines: Statistics and Physical Conditions of O VI Absorbers
• Distribution and Kinematics of O VI in the Galactic Halo
• Multi-phase High-Velocity Clouds toward HE 0226-4110 and PG 0953+414
• Photospheric Abundances: Problems, Updates, Implications
• An Accurate Distance to High-Velocity Cloud Complex C
• The Far Ultraviolet Spectroscopic Explorer Survey of OVI Absorption in the Disk of the Milky Way
• Highly Ionized Gas Surrounding High Velocity Cloud Complex C
• The MHD Kelvin-Helmholtz Instability: A Two-Dimensional Numerical Study
• The Magnetohydrodynamic Kelvin-Helmholtz Instability: A Three-Dimensional Study of Nonlinear Evolution
• The MHD Kelvin-Helmholtz Instability II: The Roles of Weak and Oblique Fields in Planar Flows
• High-Ion Absorption in Seven GRB Host Galaxies at z=2-4: Evidence for both Circumburst Plasma and Outflowing Interstellar Gas
• A Survey for NV Absorption at z~z_GRB in GRB Afterglow Spectra: Clues to Gas Near the Progenitor Star
• C IV absorption in damped and sub-damped Lyman-alpha systems: correlations with metallicity and implications for galactic winds at z~2-3
• OVI Observations of Galaxy Clusters: Evidence for Modest Cooling Flows
• Metallicity and Ionization in High Velocity Cloud Complex C
• FUSE Observations of Cooling Flow Gas in the Galaxy Clusters A1795 and A2597
• Highly ionised plasma in the Large Magellanic Cloud: Evidence for outflows and a possible galactic wind
• Highly-Ionized Gas in the Galactic Halo: A FUSE Survey of O VI Absorption toward 22 Halo Stars
• Highly Ionized Gas in the Galactic Halo and the High Velocity Clouds Toward PG 1116+215
• OVI, NV, and CIV in the Galactic Halo: I. Velocity-Dependent Ionization Models
• Observations of O VI Emission from the Diffuse Interstellar Medium
• An Extended FUSE Survey of Diffuse O VI Emission in the Interstellar Medium
• OVI, NV and CIV in the Galactic Halo: II. Velocity-Resolved Observations with Hubble and FUSE
• Metal-Enriched Plasma in Protogalactic Halos: A Survey of N V Absorption in High-z Damped & Sub-Damped Lyman-alpha Systems
• MHD Turbulent Mixing Layers: Equilibrium Cooling Models
• High-Resolution Absorption Spectroscopy of Multi-phase, High-Metallicity Gas Associated with the Luminous Quasar HE 0226-4110
• The Galactic Halo's O VI Resonance Line Intensity
• The MHD Kelvin-Helmholtz Instability III: The Role of Sheared Magnetic Field in Planar Flows
• A Useful Approximation to the Cooling Coefficient of Trace Elements
• The Far Ultraviolet Spectroscopic Explorer Survey of OVI Emission in the Milky Way
• Far-ultraviolet Observations of the North Ecliptic Pole with SPEAR
• Possible Detection of OVI from the LMC Superbubble N70
• Evidence and Implications of Pressure Fluctuations in the ISM
• SPEAR far UV spectral imaging of highly ionized emission from the North Galactic Pole Region
• The Size of the Cooling Region of Hot Gas in Two Elliptical Galaxies

Cited by in corpus (57)

• The Circumgalactic Medium
• The Structure of the Milky Way's Hot Gas Halo
• The COS-Halos Survey: Origins of the Highly Ionized Circumgalactic Medium of Star-Forming Galaxies
• The Magellanic Stream: Circumnavigating the Galaxy
• Properties of the Circumgalactic Medium in Cosmic Ray-Dominated Galaxy Halos
• A Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE).I. Introduction to the Survey
• The Properties of Low Redshift Intergalactic O VI Absorbers Determined from High S/N Observations of 14 QSOs with the Cosmic Origins Spectrograph
• Galactic and Circumgalactic OVI and its Impact on the Cosmological Metal and Baryon Budgets at 2<z<3.5
• Simulations of radiative turbulent mixing layers
• Radiative Mixing Layers: Insights from Turbulent Combustion
• Implications of the large OVI columns around low-redshift $L_{\ast }$ galaxies
• Characterizing Transition Temperature Gas in the Galactic Corona
• The Properties of the Circumgalactic Medium in Red and Blue Galaxies: Results from the COS-GASS+COS-Halos Surveys
• Simulations of High-Velocity Clouds. I. Hydrodynamics and High-Velocity High Ions
• The large-scale ionization cones in the Galaxy
• Viscous Kelvin-Helmholtz instabilities in highly ionised plasmas
• How Do Supernovae Impact the Circumgalactic Medium? I. Large-Scale Fountains Around a Milky Way-Like Galaxy
• Hubble-COS Observations of Galactic High-Velocity Clouds: Four AGN Sight Lines through Complex C
• Fundamental Properties of the Highly Ionized Plasmas in the Milky Way
• Cos observations of metal line and broad lyman alpha absorption in the multi-phase o vi and ne viii system toward he 02226-4110
• The Mass and Absorption Columns of Galactic Gaseous Halos
• Interaction of Cosmic Rays with Cold Clouds in Galactic Halos
• The Nature of Ionized Gas in the Milky Way Galactic Fountain
• Catastrophic Cooling in Superwinds: Line Emission and Non-equilibrium Ionization
• Feeding the fire: Tracing the mass-loading of 10^7 K galactic outflows with O VI absorption
• Radiative turbulent mixing layers at high Mach numbers
• The Milky Way's Hot Gas Kinematics: Signatures in Current and Future OVII Absorption Line Observations
• A Model for Line Absorption and Emission from Turbulent Mixing Layers
• Down-the-barrel and transverse observations of the Large Magellanic Cloud: evidence for a symmetrical galactic wind on the near and far sides of the galaxy
• The Surprisingly Constant Strength of O VI Absorbers over Cosmic Time
• The 21cm "Outer Arm" and the Outer-Galaxy High-Velocity Clouds: Connected by Kinematics, Metallicity, and Distance
• OVI Traces Photoionized Streams With Collisionally Ionized Boundaries in Cosmological Simulations of $z\sim 1$ Massive Galaxies
• Si iv Column Densities Predicted from Non-Equilibrium Ionization Simulations of Turbulent Mixing Layers and High-Velocity Clouds
• Cooling driven coagulation
• Self-ionizing galactic winds
• Mass, Morphing, Metallicities: The Evolution of Infalling High Velocity Clouds
• On the connection between the metal-enriched intergalactic medium and galaxies: an OVI-galaxy cross-correlation study at $z<1$
• The Anatomy of a Turbulent Radiative Mixing Layer: Insights from an Analytic Model with Turbulent Conduction and Viscosity
• The Warm Gas in the MW: A Kinematical Model
• Implications of Coronal Line Emission in NGC 4696
• A hot gaseous galaxy halo candidate with Mg X absorption
• Simulations of High-Velocity Clouds. II. Ablation from High-Velocity Clouds as a Source of Low-Velocity High Ions
• 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?
• High-ion absorption in the proximate damped Lyman-alpha system toward Q0841+129
• Modeling the X-rays Resulting from High Velocity Clouds
• Stability and Ly$\alpha$ emission of Cold Stream in the Circumgalactic Medium: impact of magnetic fields and thermal conduction
• The nearby interstellar medium towards alpha Leo -- UV observations and modeling of a warm cloud within hot gas
• In Search of an Interface between Warm and Hot Gas within the Local Bubble
• Hot Gas in the Galactic Thick Disk and Halo Near the Draco Cloud
• High-resolution observations of two OVI absorbers at z=2 towards PKS 1448-232
• A high-redshift quasar absorber without CIV - a galactic outflow caught in the act?
• The Observed O VI is Just the Tip of the Iceberg: Estimating the Hidden Material in Circumgalactic and Intergalactic Clouds
• Effect of cosmic rays and ionizing radiation on observational ultraviolet plasma diagnostics in the circumgalactic medium
• Origin of Weak MgII and Higher Ionization Absorption Lines in an Outflow from an Intermediate-Redshift Dwarf Satellite Galaxy
• A Dynamical Test for Cooling-Induced Entrainment in a Runaway Supermassive Black Hole Tail
• The Thermodynamic and Kinematic Evolution of Circumgalactic Gas around $z=1$ in the IllustrisTNG model
• Modeling Emission-Line Surface Brightness in a Multiphase Galactic Wind: An O VI Case Study