From the Fire: A Deeper Look at the Phoenix Stream
  We use six years of data from the Dark Energy Survey to perform a detailed
photometric characterization of the Phoenix stellar stream, a 15-degree long,
thin, dynamically cold, low-metallicity stellar system in the southern
hemisphere. We use natural splines, a non-parametric modeling technique, to
simultaneously fit the stream track, width, and linear density. This updated
stream model allows us to improve measurements of the heliocentric distance
($17.4 \pm 0.1\,{\rm (stat.)} \pm 0.8\,{\rm (sys.)}$ kpc) and distance gradient
($-0.009 \pm 0.006$ kpc deg$^{-1}$) of Phoenix, which corresponds to a small
change of $0.13 \pm 0.09$ kpc in heliocentric distance along the length of the
stream. We measure linear intensity variations on degree scales, as well as
deviations in the stream track on $\sim 2$-degree scales, suggesting that the
stream may have been disturbed during its formation and/or evolution. We
recover three peaks and one gap in linear intensity along with fluctuations in
the stream track. Compared to other thin streams, the Phoenix stream shows more
fluctuations and, consequently, the study of Phoenix offers a unique
perspective on gravitational perturbations of stellar streams. We discuss
possible sources of perturbations to Phoenix including baryonic structures in
the Galaxy and dark matter subhalos.
