# Proper Motions of Stellar Streams Discovered in the Dark Energy Survey

## TL;DR

This paper measures proper motions of nine stellar streams in the Dark Energy Survey by combining Gaia DR2 data with DES photometry, revealing potential gravitational effects from the Large Magellanic Cloud.

## Contribution

It provides the first high-precision proper motion measurements for multiple stellar streams in the DES footprint, highlighting possible LMC influence.

## Key findings

- Proper motions for nine stellar streams were confidently measured.
- Evidence of misalignment suggests gravitational influence from the Large Magellanic Cloud.
- Proper motions combined with radial velocities will enable detailed orbit modeling.

## Abstract

We cross-match high-precision astrometric data from Gaia DR2 with accurate multi-band photometry from the Dark Energy Survey (DES) DR1 to confidently measure proper motions for nine stellar streams in the DES footprint: Aliqa Uma, ATLAS, Chenab, Elqui, Indus, Jhelum, Phoenix, Tucana III, and Turranburra. We determine low-confidence proper motion measurements for four additional stellar streams: Ravi, Wambelong, Willka Yaku, and Turbio. We find evidence for a misalignment between stream tracks and the systemic proper motion of streams that may suggest a systematic gravitational influence from the Large Magellanic Cloud. These proper motions, when combined with radial velocity measurements, will allow for detailed orbit modeling which can be used to constrain properties of the LMC and its affect on nearby streams, as well as global properties of the Milky Way's gravitational potential.