Recent FUSE Observations of Diffuse O VI Emission from the Interstellar Medium

TL;DR

This paper reports new FUSE observations of diffuse O VI emission in the interstellar medium, revealing large-scale structures and interfaces in the Galactic halo and Magellanic System, advancing understanding of high-ionization gas distribution.

Contribution

It provides the first detections of O VI emission from the Magellanic System outside the Clouds, expanding knowledge of high-ionization gas in these regions.

Findings

Detected 13 new O VI emission regions, including from the Magellanic System.

Identified a large, low-velocity O VI layer extending over 70 degrees.

Differentiated emission sources at low and high Galactic latitudes.

Abstract

We present new results from our survey of diffuse O VI-emitting gas in the interstellar medium with the Far Ultraviolet Spectroscopic Explorer (FUSE). Background observations obtained since 2005 have yielded eleven new O VI detections of 3-sigma significance, and archival searches have revealed two more. An additional 15 sight lines yield interesting upper limits. Combined with previous results, these observations reveal the large-scale structure of the O VI-bearing gas in the quadrant of the sky centered on the Magellanic Clouds. The most prominent feature is a layer of low-velocity O VI emission extending more than 70 degrees from the Galactic plane. At low latitudes (|b| < 30 degrees), the emission comes from narrow, high-density conductive interfaces in the local ISM. At high latitudes, the emission is from extended, low-density regions in the Galactic halo. We also detect O VI emission from the interface region of the Magellanic System, a structure recently identified from H I observations. These are the first detections of emission from high-ionization species in the Magellanic System outside of the Clouds themselves.