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Title: The Dark Energy Survey view of the Sagittarius stream: discovery of two faint stellar system candidates

Journal Article · · Monthly Notices of the Royal Astronomical Society
DOI:https://doi.org/10.1093/mnras/stx405· OSTI ID:1362056
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  1. Instituto de Fisica, Porto Alegre (Brazil); Lab. Interinstitucional de e-Astronomia - LIneA, Rio de Janeiro (Brazil)
  2. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
  3. Cerro Tololo Inter-American Observatory, La Serena (Chile)
  4. National Center for Supercomputing Applications, Urbana, IL (United States)
  5. Univ. of Surrey, Guildford (United Kingdom)
  6. Texas A & M Univ., College Station, TX (United States)
  7. Lab. Interinstitucional de e-Astronomia - LIneA, Rio de Janeiro (Brazil)
  8. Lab. Interinstitucional de e-Astronomia - LIneA, Rio de Janeiro (Brazil); Observatorio Nacional, Rio de Janeiro (Brazil)
  9. Univ. of Chicago, Chicago, IL (United States)
  10. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  11. Univ. of Pennsylvania, Philadelphia, PA (United States)
  12. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Univ. of Chicago, Chicago, IL (United States)
  13. Univ. College London, London (United Kingdom)
  14. Cerro Tolol Inter-American Observatory, La Serena (Chile)
  15. Univ. College London, London (United Kingdom); Rhodes Univ., Grahamstown (South Africa)
  16. Univ. College London, London (United Kingdom); Institut d'Astrophysique de Paris, Paris (France); Sorbonne Univ., Paris (France)
  17. Institut d'Astrophysique de Paris, Paris (France); Sorbonne Univ., Paris (France)
  18. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
  19. National Center for Supercomputing Applications, Urbana, IL (United States); Univ. of Illinois, Urbana, IL (United States)
  20. Institut de Ciencies de l'Espai, Barcelona (Spain); The Barcelona Institute of Science and Technology, Barcelona (Spain)
  21. Stanford Univ., Stanford, CA (United States)
  22. Univ. of Portsmouth, Portsmouth (United Kingdom); Univ. of Southampton, Southampton (United Kingdom)
  23. IIT Hyderabad, Telangana (India)
  24. Univ. of Michigan, Ann Arbor, MI (United States)
  25. Institut de Ciencies de l'Espai, Barcelona (Spain)
  26. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)
  27. Australian Astronomical Observatory, North Ryde, NSW (Australia)
  28. The Ohio State Univ., Columbus, OH (United States)
  29. The Barcelona Institute of Science and Technology, Barcelona (Spain); Institucio Catalana de Recerca i Estudis Avancats, Barcelona (Spain)
  30. California Inst. of Technology (CalTech), Pasadena, CA (United States)
  31. Univ. of Sussex, Brighton (United Kingdom)
  32. Centro de Investigaciones Energeticas, Madrid (Spain)
  33. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  34. Univ. of Portsmouth, Portsmouth (United Kingdom)
  35. Lab. Interinstitucional de e-Astronomia - LIneA, Rio de Janeiro (Brazil); Univ. Federal do ABC, Santo Andre (Brazil)
+ Show Author Affiliations

We report the discovery of two new candidate stellar systems in the constellation of Cetus using the data from the first two years of the Dark Energy Survey (DES). The objects, DES J0111-1341 and DES J0225+0304, are located at a heliocentric distance of ~25 kpc and appear to have old and metal-poor populations. Their distances to the Sagittarius orbital plane, ~1.73 kpc (DES J0111-1341) and ~0.50 kpc (DES J0225+0304), indicate that they are possibly associated with the Sagittarius dwarf stream. The half-light radius (rh ≃ 4.55 pc) and luminosity (MV ≃ +0.3) of DES J0111-1341 are consistent with it being an ultrafaint stellar cluster, while the half-light radius (rh ≃ 18.55 pc) and luminosity (MV ≃ -1.1) of DES J0225+0304 place it in an ambiguous region of size-luminosity space between stellar clusters and dwarf galaxies. Determinations of the characteristic parameters of the Sagittarius stream, metallicity spread (-2.18 ≲ [Fe/H] ≲ -0.95) and distance gradient (23 kpc ≲ D⊙ ≲ 29 kpc), within the DES footprint in the Southern hemisphere, using the same DES data, also indicate a possible association between these systems. If these objects are confirmed through spectroscopic follow-up to be gravitationally bound systems and to share a Galactic trajectory with the Sagittarius stream, DES J0111-1341 and DES J0225+0304 would be the first ultrafaint stellar systems associated with the Sagittarius stream. Furthermore, DES J0225+0304 would also be the first confirmed case of an ultrafaint satellite of a satellite.

Research Organization:
SLAC National Accelerator Lab., Menlo Park, CA (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
USDOE Office of Science (SC), High Energy Physics (HEP)
Contributing Organization:
DES; The Dark Energy Survey Collaboration
Grant/Contract Number:
AC02-07CH11359; AC05-00OR22725; AC02-76SF00515; AC02-05CH11231
OSTI ID:
1362056
Alternate ID(s):
OSTI ID: 1352815; OSTI ID: 1361150; OSTI ID: 1476500
Report Number(s):
arXiv:1608.04033; FERMILAB-PUB-16-294; 1481252
Journal Information:
Monthly Notices of the Royal Astronomical Society, Vol. 468, Issue 1; ISSN 0035-8711
Publisher:
Royal Astronomical SocietyCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 29 works
Citation information provided by
Web of Science

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Cited By (15)

Nine tiny star clusters in Gaia DR1, PS1, and DES journal January 2019
Robust velocity dispersion and binary population modelling of the ultrafaint dwarf galaxy Reticulum II journal June 2019
The hidden giant: discovery of an enormous Galactic dwarf satellite in Gaia DR2 journal June 2019
How low does it go? Too few Galactic satellites with standard reionization quenching journal July 2019
Identification of RR Lyrae Stars in Multiband, Sparsely Sampled Data from the Dark Energy Survey Using Template Fitting and Random Forest Classification journal June 2019
Chemical Abundance Analysis of Three α -poor, Metal-poor Stars in the Ultrafaint Dwarf Galaxy Horologium I journal January 2018
On the Nature of Ultra-faint Dwarf Galaxy Candidates. II. The Case of Cetus II journal April 2018
Stellar Streams Discovered in the Dark Energy Survey journal July 2018
Dancing in the Dark: Uncertainty in Ultrafaint Dwarf Galaxy Predictions from Cosmological Simulations journal March 2019
Proper Motions of Milky Way Ultra-faint Satellites with Gaia DR2 × DES DR1 journal April 2019
A Faint Halo Star Cluster Discovered in the Blanco Imaging of the Southern Sky Survey journal April 2019
Chemical Abundance Analysis of Tucana III, the Second r -process Enhanced Ultra-faint Dwarf Galaxy journal September 2019
The hidden giant: Discovery of an enormous Galactic dwarf satellite in Gaia DR2 text January 2019
A Dark Matter Hurricane: Measuring the S1 Stream with Dark Matter Detectors text January 2018
Identification of RR Lyrae stars in multiband, sparsely-sampled data from the Dark Energy Survey using template fitting and Random Forest classification text January 2019

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