Observations of O VI Emission from the Diffuse Interstellar Medium

Abstract

We report the first Far Ultraviolet Spectroscopic Explorer (FUSE) measurements of diffuse O VI (lambda,lambda 1032,1038) emission from the general diffuse interstellar medium outside of supernova remnants or superbubbles. We observed a 30arcsec x 30arcsec region of the sky centered at l = 315 and b = -41. From the observed intensities (2930+/-290(random)+/-410(systematic) and 1790+/-260(random)+/-250(systematic) photons/cm/cm/s/sr in the 1032 and 1038 Angstrom emission lines, respectively), derived equations, and assumptions about the source location, we calculate the intrinsic intensity, electron density, thermal pressure, and emitting depth. The intensities are too large for the emission to originate solely in the Local Bubble. Thus, we conclude that the Galactic thick disk and lower halo also contribute. High velocity clouds are ruled out because there are none near the pointing direction. The calculated emitting depth is small, indicating that the O VI-bearing gas fills a small volume. The observations can also be used to estimate the cooling rate of the hot interstellar medium and constrain models. The data also yield the first intensity measurement of the C II 3s2 S1/2 to 2p2 P3/2 emission line at 1037 Angstroms and place upper limits on the intensities of ultraviolet line emission from C I, C III, Si II, S III, S IV, S VI, and Fe III.

30 pages including 5 figures and 5 tables; submitted to ApJ, October 2000; accepted by ApJ, May 2001

References in corpus (2)

• HI spectra and column densities toward HVC and IVC probes
• FUSE Detection of Diffuse Galactic O VI Emission toward the Coma and Virgo Clusters

Cited by in corpus (27)

• Constrained Simulations of the Real Universe: II. Observational Signatures of Intergalactic Gas in the Local Supercluster Region
• Distribution and Kinematics of O VI in the Galactic Halo
• The Far Ultraviolet Spectroscopic Explorer Survey of OVI Absorption in the Disk of the Milky Way
• Simulating Star Formation and Feedback in Galactic Disk Models
• Properties of O VI Absorption in the Local Interstellar Medium
• Far Ultraviolet Spectroscopy of the Intergalactic and Interstellar Absorption Toward 3C 273
• Numerical Study of Turbulent Mixing Layers with Non-Equilibrium Ionization Calculations
• X-ray and UV spectroscopy of Galactic diffuse hot gas along the LMC X--3 sight line
• The Spectroscopy of Plasma Evolution from Astrophysical Radiation Mission
• An Extended FUSE Survey of Diffuse O VI Emission in the Interstellar Medium
• Surprisingly Little O VI Emission Arises in the Local Bubble
• OVI, NV and CIV in the Galactic Halo: II. Velocity-Resolved Observations with Hubble and FUSE
• New SETI Sky Surveys for Radio Pulses
• Ultraviolet Line Emission from Metals in the Low-Redshift Intergalactic Medium
• The Galactic Halo's O VI Resonance Line Intensity
• Acceleration of energetic particles by large-scale compressible magnetohydrodynamic turbulence
• The Far Ultraviolet Spectroscopic Explorer Survey of OVI Emission in the Milky Way
• Upper limits on O VI Emission From Voyager
• FUSE Detection of Galactic OVI Emission in the Halo above the Perseus Arm
• FUSE search for 10^5-10^6 K gas in the rich clusters of galaxies Abell 2029 and Abell 3112
• Simulations of Supernova Remnants in Diffuse Media III. The Population of Buoyant Remnants Above the Milky Way's Disk
• SPEAR far UV spectral imaging of highly ionized emission from the North Galactic Pole Region
• Survey of O VI absorption in the Large Magellanic Cloud
• Excess Ultraviolet Emission at High Galactic Latitudes: A New Horizons View
• The distribution and kinematics of interstellar O~{\small VI} in the Milky Way}
• Hot Gas in the Galactic Thick Disk and Halo Near the Draco Cloud
• O~{\small VI} absorption in the Milky Way along the Large Magellanic Cloud lines of sight