# Components of the Diffuse Ultraviolet Radiation at High Latitudes

## TL;DR

This study analyzes the diffuse ultraviolet background at high Galactic latitudes using GALEX data, identifying components and dust properties, and highlighting an unexplained zero-offset in UV radiation.

## Contribution

It quantifies the components of UV background radiation and determines dust optical constants at high latitudes, revealing an unexplained zero-offset in UV measurements.

## Key findings

- Zero-offset in UV background at high latitudes (~240-394 photon units)
- Approximately half of the UV radiation is from extragalactic sources and dust-scattered starlight
- Dust grain optical constants determined as a=0.4 and g=0.8 (FUV), a=0.4 and g=0.5 (NUV)

## Abstract

We have used data from the Galaxy Evolution Explorer to study the different components of the diffuse ultraviolet background in the region between the Galactic latitudes 70-80 degree. We find an offset at zero dust column density (E(B - V) = 0) of $240 \pm 18$ photon units in the FUV (1539A) and $394 \pm 37$ photon units in the NUV (2316A). This is approximately half of the total observed radiation with the remainder divided between an extragalactic component of $114 \pm 18$ photon units in the FUV and $194 \pm 37$ photon units in the NUV and starlight scattered by Galactic dust at high latitudes. The optical constants of the dust grains were found to be a=0.4$\pm$0.1 and g=0.8$\pm$0.1 (FUV) and a=0.4$\pm$0.1 and g=0.5$\pm$0.1 (NUV). We cannot differentiate between a Galactic or extragalactic origin for the zero-offset but can affirm that it is not from any known source.