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

Abstract

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:
Research Org.:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Contributing Org.:
DES Collaboration
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
Resource Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 807; 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

Citation Formats

Bechtol, K. Eight new Milky Way companions discovered in first-year Dark Energy Survey data. United States: N. p., 2015. Web. doi:10.1088/0004-637X/807/1/50.
Bechtol, K. Eight new Milky Way companions discovered in first-year Dark Energy Survey data. United States. doi:10.1088/0004-637X/807/1/50.
Bechtol, K. Tue . "Eight new Milky Way companions discovered in first-year Dark Energy Survey data". United States. doi:10.1088/0004-637X/807/1/50. https://www.osti.gov/servlets/purl/1234887.
@article{osti_1234887,
title = {Eight new Milky Way companions discovered in first-year Dark Energy Survey data},
author = {Bechtol, K.},
abstractNote = {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.},
doi = {10.1088/0004-637X/807/1/50},
journal = {The Astrophysical Journal (Online)},
number = 1,
volume = 807,
place = {United States},
year = {2015},
month = {6}
}

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