Observations of the Diffuse FUV Background with FUSE

TL;DR

This study uses FUSE observations to map the diffuse far-ultraviolet background, revealing its patchy nature with regions of intense emission near bright stars and dark areas, and exploring its correlation with infrared emission.

Contribution

First detailed mapping of diffuse FUV background using FUSE data, highlighting its patchiness and correlation with infrared emission.

Findings

Diffuse FUV signal observed in 32 of 71 locations.

FUV brightness varies from 1600 to 2.9 x 10^5 photons cm$^{-2}$ s$^{-1}$ sr$^{-1}$ b1 b1.

Weak correlation between FUV flux and 100 micron ratio with wide variations.

Abstract

We have used observations taken under the FUSE S405/S505 channel realignment program to explore the diffuse FUV (1000 - 1200 \AA) radiation field. Of the 71 independent locations in that program, we have observed a diffuse signal in 32, ranging in brightness from 1600 photons cm$^{-2}$ s$^{-1}$ sr$^{-1}$ \AA$^{-1}$ to a maximum of $2.9 \times 10^5$ photons cm$^{-2}$ s$^{-1}$ sr$^{-1}$ \AA$^{-1} in Orion. The FUSE data confirm that the diffuse FUV sky is patchy with regions of intense emission, usually near bright stars, but also with dark regions, even at low Galactic latitudes. We find a weak correlation between the FUV flux and the 100 micron ratio but with wide variations, perhaps due to differences in the local radiation field.