• DOI:10.1088/0004-637X/813/2/109
• Corpus ID: 55909299

Eight Ultra-faint Galaxy Candidates Discovered in Year Two of the Dark Energy Survey

@article{DrlicaWagner2015EightUG,
  title={Eight Ultra-faint Galaxy Candidates Discovered in Year Two of the Dark Energy Survey},
  author={The Des Collaboration A. Drlica-Wagner and Keith C. Bechtol and Eli S. Rykoff and E. Luque and Anna. B. A. Queiroz and Y.-Y. Mao and Risa H. Wechsler and Joshua D. Simon and Bas{\'i}lio Xavier Santiago and Brian Yanny and Eduardo Balbinot and Scott Dodelson and Angelo Fausti Neto and David J. James and T. S. Li and Marcio A. G. Maia and Jennifer L. Marshall and A. Pieres and K. M. Stringer and Alistair R. Walker and Timothy M. C. Abbott and Filipe B. Abdalla and Sahar Allam and Aur{\'e}lien Benoit-L{\'e}vy and Gary M. Bernstein and Emmanuel Bertin and David Brooks and Elizabeth Buckley-Geer and David L. Burke and Aurelio Carnero Rosell and Matias Carrasco Kind and Jorge Carretero and Mart{\'i}n Crocce and Luiz Nicolaci da Costa and Shantanu Desai and H. Thomas Diehl and J. P. Dietrich and Peter Doel and T. F. Eifler and August E. Evrard and David A. Finley and Brenna L. Flaugher and Pablo Fosalba and Joshua A. Frieman and Enrique Gazta{\~n}aga and David W. Gerdes and Daniel Gruen and Robert A. Gruendl and Gaston R. Guti{\'e}rrez and Klaus Honscheid and Kyler W. Kuehn and Nikolay Kuropatkin and Ofer Lahav and Paul Martini and Ramon Miquel and Brian Nord and R. L. C. Ogando and Andreas Alejandro Plazas and Kevin Alexander Reil and Aaron Roodman and Masao Sako and Eusebio S{\'a}nchez and Victor E. Scarpine and Michael S. Schubnell and Ignacio Sevilla-Noarbe and R. C. Smith and Marcelle Soares-Santos and Flavia Sobreira and Eric Suchyta and Mollye E. C. Swanson and Gregory G. Tarl{\'e} and Douglas L. Tucker and Vinu Vikram and William C. Wester and Y. Zhang and Joe Zuntz},
  journal={The Astrophysical Journal},
  year={2015},
  volume={813},
  pages={109}
}

• T. D. C. A. Drlica-Wagner, K. Bechtol, +73 authors J. Zuntz
• Published 14 August 2015
• Physics
• The Astrophysical Journal

We report the discovery of eight new ultra-faint dwarf galaxy candidates in the second year of optical imaging data from the Dark Energy Survey (DES). Six of these candidates are detected at high confidence, while two lower-confidence candidates are identified in regions of non-uniform survey coverage. The new stellar systems are found by three independent automated search techniques and are identified as overdensities of stars, consistent with the isochrone and luminosity function of an old and metal-poor simple stellar population. The new systems are faint (MV > −4.7 $\mathrm{mag}$) and span a range of physical sizes (17 $\mathrm{pc}$ < r(1/2) < 181 $\mathrm{pc}$) and heliocentric distances (25 kpc < D(⊙) < 214 kpc). All of the new systems have central surface brightnesses consistent with known ultra-faint dwarf galaxies (μ ≳ 27.5 $\mathrm{mag}$ $\mathrm{arcsec}$(−)(2)). Roughly half of the DES candidates are more distant, less luminous, and/or have lower surface brightnesses than previously known Milky Way satellite galaxies. Most of the candidates are found in the southern part of the DES footprint close to the Magellanic Clouds. We find that the DES data alone exclude (p < 10(−)(3)) a spatially isotropic distribution of Milky Way satellites and that the observed distribution can be well, though not uniquely, described by an association between several of the DES satellites and the Magellanic system. Our model predicts that the full sky may hold ∼100 ultra-faint galaxies with physical properties comparable to the DES satellites and that 20%–30% of these would be spatially associated with the Magellanic Clouds.