Testing Global ISM Models: A Detailed Comparison of Ovi Column Densities with FUSE and Copernicus Data

Abstract

We study the ovi distribution in space and time in a representative section of the Galactic disk by 3D adaptive mesh refinement HD and MHD simulations of the ISM, including the disk-halo-disk circulation. The simulations describe a supernova driven ISM on large (10 kpc) and small (1.25 pc) scales over a sufficiently large timescale (400 Myrs) in order to establish a global dynamical equilibrium. The Ovi column density, N(Ovi), is monitored through lines of sight measurements at different locations in the simulated disk. One has been deliberately chosen to be inside of a hot bubble, like our own Local Bubble, while the other locations are random. We obtain a correlation between N(Ovi) and distance, which is independent of the observer's vantage point in the disk. In particular, the location of the observer inside a hot bubble does not have any influence on the correlation, because the contribution of an individual bubble (with a typical extension of 100 pc) is negligibly small. We find a remarkable agreement between the Ovi column densities (as a function of distance) and the averaged Ovi density (~1.8x10^{-8}$cm$^{-3}$) in the disk from our simulations and the values observed with Copernicus, and FUSE. Our results strongly support the important rôle of turbulent mixing in the distribution of Ovi clumps in the ISM. Supernova induced turbulence is quite strong and unavoidable due to shearing motions in the ISM and operates on a large range of scales.

4 pages using emulateapj5 style, 5 figures including a simulation image. Accepted for publication in ApJ Letters

References in corpus (3)

• Global Dynamical Evolution of the ISM in Star Forming Galaxies - I. High Resolution 3D HD and MHD Simulations: Effect of the Magnetic Field
• Volume Filling Factors of the ISM Phases in Star Forming Galaxies - I. The Role of the Disk-Halo Interaction
• A Survey of OVI Absorption in the Local Interstellar Medium

Cited by in corpus (25)

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• The Far Ultraviolet Spectroscopic Explorer Survey of OVI Absorption in the Disk of the Milky Way
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• The History and Future of the Local and Loop I Bubbles
• The Extension of the Transition Temperature Plasma into the Lower Galactic Halo
• Characterizing Transition Temperature Gas in the Galactic Corona
• Magnetic fields and gas in the cluster-influenced spiral galaxy NGC 4254 - II. Structures of magnetic fields
• The Fractional Ionization of the Warm Neutral Interstellar Medium
• The Turbulent Interstellar Medium
• Multi-wavelength observations of a nearby multi-phase interstellar cloud
• On the distance to the North Polar Spur and the local CO-H2 factor
• Compact HI clouds from the GALFA-HI survey
• Simulations of Mixed Morphology Supernova Remnants With Anisotropic Thermal Conduction
• Simulating Anisotropic Thermal Conduction in Supernova Remnants, Implications for the Interstellar Medium
• Galactic fountains and outflows in star forming dwarf galaxies: ISM expulsion and chemical enrichment
• The age of blue LSB galaxies
• The hot interstellar medium towards 4U 1820-30: a Bayesian analysis
• Anisotropic Thermal Conduction in Supernova Remnants: Relevance to Hot Gas Filling Factors in the Magnetized ISM
• OVI Emission From the Supernovae-regulated Interstellar Medium: Simulation Vs Observation
• Indirect Dark Matter Signals
• Supernova-driven interstellar turbulence and the galactic dynamo
• Dynamical Evolution of a Supernova Driven Turbulent Interstellar Medium