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From the Fire: A Deeper Look at the Phoenix Stream

Published version
Peer-reviewed

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Abstract

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±0.1(stat.)±0.8(sys.) kpc) and distance gradient (−0.009±0.006 kpc deg−1) of Phoenix, which corresponds to a small change of 0.13±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 ∼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.

Description

Keywords

Cosmology, Dark matter, Stellar streams, Galaxy structure, Astronomy data modeling, Milky Way dynamics

Journal Title

Astrophysical Journal

Conference Name

Journal ISSN

0004-637X
1538-4357

Volume Title

925

Publisher

American Astronomical Society
Sponsorship
STFC (ST/T003081/1)