EIGHT ULTRA-FAINT GALAXY CANDIDATES DISCOVERED IN YEAR TWO OF THE DARK ENERGY SURVEY

By Alex Drlica-Wagner, K. Bechtol, Eli S. Rykoff, E. Luque, A. Queiroz, Yao-Yuan Mao, Risa Wechsler, J. Simon, B. Santiago, Brian Yanny and 66 more. 2015

348 citations recorded by the source corpus.

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 mag ?> ) and span a range of physical sizes (17 pc ?> < r1/2 < 181 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 mag ?> 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.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/390de15126ab618a97c0c5e061698a25f9af3498

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Citations in the corpus

The SAGA Survey. I. Satellite Galaxy Populations around Eight Milky Way Analogs (2017, background): “…the number of faint satellites (Mr > −10) is steadily increasing due to discoveries in ongoing large-area imaging surveys (e.g., Koposov et al. 2015; Drlica-Wagner et al. 2015), the number of bright satellites (Mr < −10) has remained unchanged since the discovery of the disrupting Sagittarius…”
The Local Group on FIRE: dwarf galaxy populations across a suite of hydrodynamic simulations (2018, neutral): “(Belokurov et al. 2009) and DES (Drlica-Wagner et al. 2015).”
Primordial black holes as generators of cosmic structures (2018, background): “These dwarfs, forming before reionization, are the building blocks of the next generation of dwarf galaxies, some of which may correspond to the extremely metal-poor ultra-faint dwarfs detected in recent deep surveys (Drlica-Wagner et al. 2015; Kim, Peter & Hargis 2017; Newton et al. 2017).”
Milky Way Satellite Census. I. The Observational Selection Function for Milky Way Satellites in DES Y3 and Pan-STARRS DR1 (2019, methodology): “Likelihood-based Search The second search algorithm employs a likelihoodbased approach implemented with the ugali framework (Bechtol et al. 2015; Drlica-Wagner et al. 2015).8 A likelihood function is constructed from the product of Poisson probabilities to detect individual stars based upon their…”
Gaia DR2 proper motions of dwarf galaxies within 420 kpc (2018, background): “This satellite has a short tidal stream (Drlica-Wagner et al. 2015) that was covered spectroscopically by Li et al. (2018a).”
A MegaCam Survey of Outer Halo Satellites. III. Photometric and Structural Parameters (2018, neutral): “Finally, we reflect upon the discovery histories of Galactic globular clusters and dwarf galaxies, with the benefit of 10 For completeness, we include four known or suspected dwarf satellites of the Milky Way (Sag, Kim 1, Draco II and Tucana III) that have RGC < 25 kpc and are thus, strictly speakin”
DETAILED CHEMICAL ABUNDANCES IN THE r-PROCESS-RICH ULTRA-FAINT DWARF GALAXY RETICULUM 2 (2016, methodology): “Images obtained by the Dark Energy Survey (DES; Diehl et al. 2014) have recently revealed 17 new faint Milky Way satellite candidates toward the general direction of the Magellanic Clouds (Bechtol et al. 2015; Drlica-Wagner et al. 2015; Koposov et al. 2015a).”
Mining for Dark Matter Substructure: Inferring Subhalo Population Properties from Strong Lenses with Machine Learning (2019, background): “…detection of ultrafaint dwarf galaxies through the study of stellar overdensities and kinematics (Koposov et al. 2008, 2015; Bechtol et al. 2015; Drlica-Wagner et al. 2015) can be used to make statements about the underlying dark matter properties, theoretical uncertainties in the connection…”
Farthest Neighbor: The Distant Milky Way Satellite Eridanus II (2016, background): “This value is consistent with the value predicted from a simple distance scaling based on the J-factors of known dwarfs (e.g., Drlica-Wagner et al. 2015b).”
SEARCHING FOR DARK MATTER ANNIHILATION IN RECENTLY DISCOVERED MILKY WAY SATELLITES WITH FERMI-LAT (2016, methodology): “This sample includes four ambiguous systems: Cetus II, Eridanus III, Kim 2, and Tucana V.”