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Title: Proper Motions of Milky Way Ultra-faint Satellites with Gaia DR2 × DES DR1

Abstract

We present a new, probabilistic method for determining the systemic proper motions of Milky Way (MW) ultra-faint satellites in the Dark Energy Survey (DES). We utilize the superb photometry from the first public data release (DR1) of the DES to select candidate members and cross-match them with the proper motions from the Gaia DR2. We model the candidate members with a mixture model (satellite and MW) in spatial and proper motion space. This method does not require prior knowledge of satellite membership and can successfully determine the tangential motion of 13 DES satellites. With our method, we present measurements of the following satellites: Columba I, Eridanus III, Grus II, Phoenix II, Pictor I, Reticulum III, and Tucana IV. This is the first systemic proper motion measurement for several of these satellites, and the majority lack extensive spectroscopic follow-up studies. We compare these to the predictions of Large Magellanic Cloud satellites and the vast polar structure. With the high-precision DES photometry, we conclude that most of the newly identified member stars are very metal-poor ([Fe/H] ≲ –2), similar to other ultra-faint dwarf galaxies, while Reticulum III is likely more metal-rich. We also find potential members in the following satellites that might indicate their overall proper motion: Cetus II, Kim 2, and Horologium II.more » Furthermore, due to the small number of members in each satellite, spectroscopic follow-up observations are necessary to determine the systemic proper motion in these satellites.« less

Authors:
ORCiD logo [1]; ORCiD logo [2]
  1. Texas A & M Univ., College Station, TX (United States)
  2. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Univ. of Chicago, Chicago, IL (United States)
Publication Date:
Research Org.:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
OSTI Identifier:
1511665
Report Number(s):
arXiv:1806.02345; FERMILAB-PUB-18-768-A
Journal ID: ISSN 1538-4357; 1730707
Grant/Contract Number:  
AC02-07CH11359
Resource Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 875; Journal Issue: 1; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; galaxies: dwarf; galaxies: kinematics and dynamics; Local Group; proper motions; stars:kinematics and dynamics

Citation Formats

Pace, Andrew B., and Li, Ting S. Proper Motions of Milky Way Ultra-faint Satellites with Gaia DR2 × DES DR1. United States: N. p., 2019. Web. doi:10.3847/1538-4357/ab0aee.
Pace, Andrew B., & Li, Ting S. Proper Motions of Milky Way Ultra-faint Satellites with Gaia DR2 × DES DR1. United States. doi:10.3847/1538-4357/ab0aee.
Pace, Andrew B., and Li, Ting S. Wed . "Proper Motions of Milky Way Ultra-faint Satellites with Gaia DR2 × DES DR1". United States. doi:10.3847/1538-4357/ab0aee.
@article{osti_1511665,
title = {Proper Motions of Milky Way Ultra-faint Satellites with Gaia DR2 × DES DR1},
author = {Pace, Andrew B. and Li, Ting S.},
abstractNote = {We present a new, probabilistic method for determining the systemic proper motions of Milky Way (MW) ultra-faint satellites in the Dark Energy Survey (DES). We utilize the superb photometry from the first public data release (DR1) of the DES to select candidate members and cross-match them with the proper motions from the Gaia DR2. We model the candidate members with a mixture model (satellite and MW) in spatial and proper motion space. This method does not require prior knowledge of satellite membership and can successfully determine the tangential motion of 13 DES satellites. With our method, we present measurements of the following satellites: Columba I, Eridanus III, Grus II, Phoenix II, Pictor I, Reticulum III, and Tucana IV. This is the first systemic proper motion measurement for several of these satellites, and the majority lack extensive spectroscopic follow-up studies. We compare these to the predictions of Large Magellanic Cloud satellites and the vast polar structure. With the high-precision DES photometry, we conclude that most of the newly identified member stars are very metal-poor ([Fe/H] ≲ –2), similar to other ultra-faint dwarf galaxies, while Reticulum III is likely more metal-rich. We also find potential members in the following satellites that might indicate their overall proper motion: Cetus II, Kim 2, and Horologium II. Furthermore, due to the small number of members in each satellite, spectroscopic follow-up observations are necessary to determine the systemic proper motion in these satellites.},
doi = {10.3847/1538-4357/ab0aee},
journal = {The Astrophysical Journal (Online)},
number = 1,
volume = 875,
place = {United States},
year = {2019},
month = {4}
}

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This content will become publicly available on April 17, 2020
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