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Title: Digging deeper into the Southern skies: A compact Milky Way companion discovered in first-year Dark Energy Survey data

Abstract

Here, we use the first-year Dark Energy Survey (DES) data down to previously unprobed photometric depths to search for stellar systems in the Galactic halo, therefore complementing the previous analysis of the same data carried out by our group earlier this year. Our search is based on a matched filter algorithm that produces stellar density maps consistent with stellar population models of various ages, metallicities, and distances over the survey area. The most conspicuous density peaks in these maps have been identified automatically and ranked according to their significance and recurrence for different input models. We report the discovery of one additional stellar system besides those previously found by several authors using the same first-year DES data. The object is compact, and consistent with being dominated by an old and metal-poor population. DES 1 is found at high significance and appears in the DES images as a compact concentration of faint blue point sources. Assuming different spatial profile parameterizations, the best-fitting heliocentric distance and total absolute magnitude in the range of 77.6–87.1 kpc and -3.00 ≲ MV ≲ -2.21, respectively. The half-light radius of this object, rh ~ 10 pc and total luminosity are consistent with it being a low-massmore » halo cluster. It is also found to have a very elongated shape (ϵ ~ 0.57). In addition, our deeper probe of DES first-year data confirms the recently reported satellite galaxy candidate Horologium II as a significant stellar overdensity. We also infer its structural properties and compare them to those reported in the literature.« less

Authors:
 [1]
  1. Instituto de Fisica, Porto Alegre (Brazil); Lab. Interinstitucional de e-Astronomia - LIneA, Rio de Janeiro (Brazil). et al.
Publication Date:
Research Org.:
SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP)
Contributing Org.:
DES Collaboration
OSTI Identifier:
1247534
Alternate Identifier(s):
OSTI ID: 1256636
Report Number(s):
arXiv:1508.02381; FERMILAB-PUB-15-455-AE; SLAC-PUB-16552
Journal ID: ISSN 0035-8711; 1388125
Grant/Contract Number:  
AC02-07CH11359; AC02-76SF00515
Resource Type:
Accepted Manuscript
Journal Name:
Monthly Notices of the Royal Astronomical Society
Additional Journal Information:
Journal Volume: 458; Journal Issue: 1; Journal ID: ISSN 0035-8711
Publisher:
Royal Astronomical Society
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; globular clusters: general; globular clusters: individual (DES 1); galaxies: dwarf; globular clusters; individual (DES 1)

Citation Formats

Luque, E. Digging deeper into the Southern skies: A compact Milky Way companion discovered in first-year Dark Energy Survey data. United States: N. p., 2016. Web. doi:10.1093/mnras/stw302.
Luque, E. Digging deeper into the Southern skies: A compact Milky Way companion discovered in first-year Dark Energy Survey data. United States. https://doi.org/10.1093/mnras/stw302
Luque, E. Tue . "Digging deeper into the Southern skies: A compact Milky Way companion discovered in first-year Dark Energy Survey data". United States. https://doi.org/10.1093/mnras/stw302. https://www.osti.gov/servlets/purl/1247534.
@article{osti_1247534,
title = {Digging deeper into the Southern skies: A compact Milky Way companion discovered in first-year Dark Energy Survey data},
author = {Luque, E.},
abstractNote = {Here, we use the first-year Dark Energy Survey (DES) data down to previously unprobed photometric depths to search for stellar systems in the Galactic halo, therefore complementing the previous analysis of the same data carried out by our group earlier this year. Our search is based on a matched filter algorithm that produces stellar density maps consistent with stellar population models of various ages, metallicities, and distances over the survey area. The most conspicuous density peaks in these maps have been identified automatically and ranked according to their significance and recurrence for different input models. We report the discovery of one additional stellar system besides those previously found by several authors using the same first-year DES data. The object is compact, and consistent with being dominated by an old and metal-poor population. DES 1 is found at high significance and appears in the DES images as a compact concentration of faint blue point sources. Assuming different spatial profile parameterizations, the best-fitting heliocentric distance and total absolute magnitude in the range of 77.6–87.1 kpc and -3.00 ≲ MV ≲ -2.21, respectively. The half-light radius of this object, rh ~ 10 pc and total luminosity are consistent with it being a low-mass halo cluster. It is also found to have a very elongated shape (ϵ ~ 0.57). In addition, our deeper probe of DES first-year data confirms the recently reported satellite galaxy candidate Horologium II as a significant stellar overdensity. We also infer its structural properties and compare them to those reported in the literature.},
doi = {10.1093/mnras/stw302},
journal = {Monthly Notices of the Royal Astronomical Society},
number = 1,
volume = 458,
place = {United States},
year = {Tue Feb 09 00:00:00 EST 2016},
month = {Tue Feb 09 00:00:00 EST 2016}
}

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