Modeling the cosmic ultraviolet background at the north galactic pole

Abstract

I explore models of the dust-scattered component of the cosmic ultraviolet background (CUVB) at the north galactic pole (NGP) to develop a framework for calculating the dust-scattered light as a function of the optical depths. As expected, I find that the dust-scattered emission scales linearly, with reddening up to \(E(B-V) \approx 0.1\) mag and derive a parametric model for this dependence. I have applied these models to fit the far-ultraviolet (1350–1800 Å) observations from the galaxy evolution explorer (GALEX) finding that the optical constants of the interstellar dust grains—albedo (a) and phase function asymmetry factor (g)—are consistent with predictions from the Astrodust model (\(a = 0.33\), \(g = 0.68\)). I detect an isotropic offset of \(267 \pm 7\) ph cm\(^{-2}\) s\(^{-1}\) sr\(^{-1}\) Å\(^{-1}\), half of which remains unaccounted for, by known Galactic or extragalactic sources. I will now extend my analysis to wider sky regions with the goal of generating high-resolution extinction maps.