W2246-0526 is a Hot Dust Obscured Galaxy (Hot DOG) at redshift 4.6, and the most luminous obscured quasar known to date. I will present ALMA observations of this Hot DOG for the brightest far-IR fine-structure emission lines, as well as of their underlying dust continuum. A comparison of the data with a large grid of CLOUDY radiative transfer models reveals that the conditions of the interstellar medium of the galaxy need to be extreme: high hydrogen density and extinction, together with intense ionization and a high X-ray to UV ratio, among the largest found in the literature. This (and future planned) work sheds light on the extreme conditions that galaxies can experience during the early stages of the Universe, a piece of information that is critical to our understanding of how distant and young galaxies evolve.
A burning Hot DOG: the extreme ISM conditions of the most luminous obscured galaxy in the Universe
