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

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 Galacticmore » trajectory with the Sagittarius stream, DES J0111–1341 and DES J0225+0304 would be the first ultrafaint stellar systems associated with the Sagittarius stream. Moreover, DES J0225+0304 would also be the first confirmed case of an ultrafaint satellite of a satellite.« less
Authors:
 [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [1] ;  [2] ;  [4] ;  [5] ;  [6] ;  [6] ;  [7] ;  [8] ;  [8] ;  [9] ;  [10] ;  [11] ;  [12] ;  [13] ;  [2] more »;  [2] ;  [14] ;  [15] ;  [2] ;  [2] ;  [16] ;  [17] ;  [13] ;  [18] ;  [8] ;  [19] ;  [20] ;  [21] ;  [22] ;  [23] ;  [13] ;  [24] ;  [2] ;  [25] ;  [24] ;  [26] ;  [18] ;  [19] ;  [2] ;  [14] ;  [27] ;  [2] ;  [13] ;  [28] ;  [29] ;  [2] ;  [8] ;  [30] ;  [31] ;  [32] ;  [2] ;  [24] ;  [32] ;  [14] ;  [2] ;  [33] ;  [4] ;  [24] ;  [34] ;  [14] ;  [35] « less
  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)
Publication Date:
Report Number(s):
arXiv:1608.04033; FERMILAB-PUB-16-294
Journal ID: ISSN 0035-8711; KJ0402000; KJ0503000; ERKJ311; ERKJEPM; TRN: US1700708
Grant/Contract Number:
AC05-00OR22725; AC02-76SF00515; AC02-07CH11359
Type:
Accepted Manuscript
Journal Name:
Monthly Notices of the Royal Astronomical Society
Additional Journal Information:
Journal Volume: 468; Journal Issue: 1; Journal ID: ISSN 0035-8711
Publisher:
Royal Astronomical Society
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); 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)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Contributing Orgs:
The Dark Energy Survey Collaboration; DES
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; globular clusters: general; galaxies: dwarf
OSTI Identifier:
1362056
Alternate Identifier(s):
OSTI ID: 1352815; OSTI ID: 1361150