# Hot Dust-Obscured Galaxies with Excess Blue Light

## TL;DR

This study investigates Hot Dust-Obscured Galaxies with excess UV light, revealing that the UV emission mainly originates from scattered light of the obscured AGN, with possible star formation contributions.

## Contribution

It provides new high-resolution imaging and X-ray observations of three Hot DOGs with UV excess, clarifying the origin of their UV emission.

## Key findings

- UV excess is mainly due to scattered AGN light
- High obscuration levels in Hot DOGs confirmed
- Star formation may contribute to UV emission in some cases

## Abstract

Hot Dust-Obscured Galaxies (Hot DOGs) are among the most luminous galaxies in the Universe. Powered by highly obscured, possibly Compton-thick, active galactic nuclei (AGNs), Hot DOGs are characterized by SEDs that are very red in the mid-IR yet dominated by the host galaxy stellar emission in the UV and optical. An earlier study identified a sub-sample of Hot DOGs with significantly enhanced UV emission. One target, W0204-0506, was studied in detail and, based on Chandra observations, it was concluded that the enhanced emission was most likely due to either extreme unobscured star-formation (${\rm SFR}>1000~M_{\odot}~\rm yr^{-1}$) or to light from the highly obscured AGN scattered by gas or dust into our line of sight. Here, we present a follow-up study of W0204-0506 as well as two more Hot DOGs with excess UV emission. For the two new objects we obtained Chandra/ACIS-S observations, and for all three targets we obtained HST/WFC3 F555W and F160W imaging. We conclude that the excess UV emission is primarily dominated by light from the central highly obscured, hyper-luminous AGN that has been scattered into our line of sight. We cannot rule out, however, that star-formation may significantly contribute to the UV excess of W0204-0506.