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Title: Eight new Milky Way companions discovered in first-year Dark Energy Survey data

We report the discovery of eight new Milky Way companions in $$\sim 1800\;{\mathrm{deg}}^{2}$$ of optical imaging data collected during the first year of the Dark Energy Survey (DES). Each system is identified as a statistically significant over-density of individual stars consistent with the expected isochrone and luminosity function of an old and metal-poor stellar population. The objects span a wide range of absolute magnitudes (MV from $-2.2$ to $$-7.4\;\mathrm{mag}$$), physical sizes ($$10-170\;\mathrm{pc}$$), and heliocentric distances ($$30-330\;\mathrm{kpc}$$). Based on the low surface brightnesses, large physical sizes, and/or large Galactocentric distances of these objects, several are likely to be new ultra-faint satellite galaxies of the Milky Way and/or Magellanic Clouds. We introduce a likelihood-based algorithm to search for and characterize stellar over-densities, as well as identify stars with high satellite membership probabilities. As a result, we also present completeness estimates for detecting ultra-faint galaxies of varying luminosities, sizes, and heliocentric distances in the first-year DES data.
Authors:
 [1]
  1. Univ. of Chicago, Chicago, IL (United States). et al.
Publication Date:
OSTI Identifier:
1234887
Report Number(s):
FERMILAB-PUB--15-047-AE
Journal ID: ISSN 1538-4357; arXiv eprint number arXiv:1503.02584
Grant/Contract Number:
AC02-07CH11359
Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal
Additional Journal Information:
Journal Volume: 807; Journal Issue: 1; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Research Org:
Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Contributing Orgs:
DES Collaboration
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS