Observations of Far-Ultraviolet Diffuse Emission from the Small Magellanic Cloud

TL;DR

This paper presents the first measurements of far-ultraviolet diffuse emission from the Small Magellanic Cloud, revealing its intensity, contribution to the total radiation, and correlation with H-alpha emission, using FUSE observations.

Contribution

It provides the first observational data on FUV diffuse emission from the SMC and compares it with the LMC, highlighting differences in diffuse fractions and dust properties.

Findings

FUV diffuse emission ranges from detection limit to 3x10^5 photons cm^-2 s^-1 sr^-1 Å^-1.

Diffuse emission contributes 34-44% to the total FUV radiation field.

FUV diffuse emission correlates with H-alpha emission in SMC H II regions.

Abstract

We report the first observations of far-ultraviolet (FUV: 1000 -- 1150 \AA) diffuse radiation from the Small Magellanic Cloud (SMC) using observations from the {\em Far Ultraviolet Spectroscopic Explorer (FUSE)}. The strength of FUV diffuse surface brightness in the SMC ranges from the detection limit of 2000 photons cm$^{-2}$ s$^{-1}$ sr$^{-1}$ \AA$^{-1}$ to a maximum of $3 \times 10^{5}$ photons cm$^{-2}$ s$^{-1}$ sr$^{-1}$ \AA$^{-1}$ at 1004 \AA. The contribution of diffuse emission to the total radiation field was found to be 34% at 1004 \AA to 44% at 1117 \AA with a maximum observed uncertainty of 30%. There is a striking difference between the FUV diffuse fraction from the SMC and the Large Magellanic Cloud (LMC) with the SMC fraction being higher probable because the higher dust albedo. The FUV diffuse emission correlates with H$\alpha$ emission in the H {\small II} regions of the SMC.