GALEX Observations of Diffuse UV Radiation at High Spatial Resolution from the Sandage Nebulosity

Abstract

Using the GALEX ultraviolet imagers we have observed a region of nebulosity first identified as starlight scattered by interstellar dust by Sandage (1976). Apart from airglow and zodiacal emission, we have found a diffuse UV background of between 500 and 800 \phunit in both the \galex FUV (1350 -- 1750 Å) and NUV (1750 -- 2850 Å). Of this emission, up to 250 \phunit is due to \htwo fluorescent emission in the FUV band; the remainder is consistent with scattering from interstellar dust. We have estimated the optical constants to be $a=0.3;g=0.7$ in the FUV and $a=0.5;g=0.7$ in the NUV, implying highly forward scattering grains, plus an extragalactic contribution of as much as 150 \phunit. These are the highest spatial resolution observations of the diffuse UV background to date and show an intrinsic scatter beyond that expected from instrumental noise alone. Further modeling is required to understand the nature of this scatter and its implications for the ISM.

Total 20 pages, Figures 9, Accepted for publication in Astrophysical Journal

References in corpus (5)

• The Galaxy Evolution Explorer: A Space Ultraviolet Survey Mission
• Molecular Hydrogen Optical Depth Templates for FUSE Data Analysis
• Observations of the Diffuse FUV Background with FUSE
• Dust Properties in the FUV in Ophiuchus
• Measurement of Dust Optical Properties in Coalsack

Cited by in corpus (12)

• Mapping the Diffuse Ultraviolet Sky with GALEX
• Ultraviolet to optical diffuse sky emission as seen by the Hubble Space Telescope Faint Object Spectrograph
• The Mystery of the Cosmic Diffuse Ultraviolet Background Radiation
• Observations of Diffuse Ultraviolet Emission from Draco
• Dust depletion, chemical uniformity and environment of CaII H&K quasar absorbers
• Modelling Dust Scattering in our Galaxy
• Components of the Diffuse Ultraviolet Radiation at High Latitudes
• GALEX FUV Observations of Comet C/2004 Q2 (Machholz): The Ionization Lifetime of Carbon
• World Space Observatory-Ultraviolet: ISSIS, the imaging instrument
• Dust-Scattered Ultraviolet Halos around Bright Stars
• First Detection of UV emission from a Detached Dust Shell: GALEX Observations of the Carbon AGB Star U Hya
• Constraining $z\lesssim 2$ ultraviolet emission with the upcoming ULTRASAT satellite