EIGHT NEW MILKY WAY COMPANIONS DISCOVERED IN FIRST-YEAR DARK ENERGY SURVEY DATA

By K. Bechtol, Alex Drlica-Wagner, E. Balbinot, A. Pieres, J. Simon, Brian Yanny, B. Santiago, Risa Wechsler, Joshua A. Frieman, A. Walker and 83 more. 2015

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We report the discovery of eight new Milky Way companions in ∼ 1800 deg 2 ?> of optical imaging data collected during the first year of the Dark Energy Survey (DES). Each system is identified as a statistically significant over-density of individual stars consistent with the expected isochrone and luminosity function of an old and metal-poor stellar population. The objects span a wide range of absolute magnitudes (MV from − 2.2 ?> to − 7.4 mag ?> ), physical sizes ( 10 − 170 pc ?> ), and heliocentric distances ( 30 − 330 kpc ?> ). Based on the low surface brightnesses, large physical sizes, and/or large Galactocentric distances of these objects, several are likely to be new ultra-faint satellite galaxies of the Milky Way and/or Magellanic Clouds. We introduce a likelihood-based algorithm to search for and characterize stellar over-densities, as well as identify stars with high satellite membership probabilities. We also present completeness estimates for detecting ultra-faint galaxies of varying luminosities, sizes, and heliocentric distances in the first-year DES data.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/d66a0df87aef2542fa8f130345f30055c0d774c4

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Citations in the corpus

The Pristine survey - I. Mining the Galaxy for the most metal-poor stars (2017, background): “Satellite discoveries in the SDSS (e.g., Belokurov et al. 2007), Pan-STARRS1 (e.g., Laevens et al. 2015), and the Dark Energy Survey (e.g., Bechtol et al. 2015) have provided us with powerful observational constraints in our cosmic backyard, especially to understand the faint end of galaxy…”
EIGHT ULTRA-FAINT GALAXY CANDIDATES DISCOVERED IN YEAR TWO OF THE DARK ENERGY SURVEY (2015, methodology): “To quantify our search sensitivity with the Y2Q1 data set, we follow the approach that Bechtol et al. (2015) applied to the DES Y1A1 coadd data.”
SAGITTARIUS II, DRACO II AND LAEVENS 3: THREE NEW MILKY WAY SATELLITES DISCOVERED IN THE PAN-STARRS 1 3π SURVEY (2015, background): “These new satellites, located close to the Magellanic Clouds (Bechtol et al. 2015; Kirby et al. 2015; Koposov et al. 2015), have emphasized the tendency of these faint stellar systems to be brought into the MW surroundings in groups.”
WIMP dark matter candidates and searches—current status and future prospects (2017, background): “er observation targets or channels. In particular a similar excess can be searched for in the dwarf spheroidal galaxies. Recently the Dark Energy Survey discovered several new dwarf galaxy candidates [309]. In particular, some tentative evidence was proposed for a gamma-ray excess in the direction o”
SEARCH FOR GAMMA-RAY EMISSION FROM DES DWARF SPHEROIDAL GALAXY CANDIDATES WITH FERMI-LAT DATA (2015, background): “…in the southern hemisphere ( 1600 deg2~ not overlapping with SDSS).68 Recent studies of the Y1A1 data set have revealed eight new dSph candidates (Bechtol et al. 2015; Koposov et al. 2015).69 Since the LAT continuously surveys the entire sky, LAT data collected over the duration of the mission…”
Farthest Neighbor: The Distant Milky Way Satellite Eridanus II (2016, methodology): “Over the past two years, more than 20 ultra-faint dwarf galaxy candidates have been discovered in data from the Dark Energy Survey (DES; Bechtol et al. 2015; Koposov et al. 2015; Drlica-Wagner et al. 2015a; Kim & Jerjen 2015) and other large optical surveys (Martin et al. 2015; Laevens et al.…”
DETAILED CHEMICAL ABUNDANCES IN THE r-PROCESS-RICH ULTRA-FAINT DWARF GALAXY RETICULUM 2 (2016, methodology): “The 10 UFD galaxies whose stars have been observed at high spectral resolution (see references in caption to Figure 2) have a combined stellar mass of ∼ 1.1×105 M (McConnachie 2012; Bechtol et al. 2015).”
A MegaCam Survey of Outer Halo Satellites. III. Photometric and Structural Parameters (2018, methodology): “By contrast, Bechtol et al. (2015) report MV = −7.40±0.10 and Re = 172±57 pc. Crnojevic et al. (2016) published deeper photometry and reported MV = −7.1±0.3 and Re = 277±14 pc. 4.”
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…”
The upper bound on the lowest mass halo (2016, background): “First, of the ∼ 20 new discoveries recently made in in the Dark Energy Survey (DES) (Koposov et al. 2015; Bechtol et al. 2015; Drlica-Wagner et al. 2015; Kim et al. 2015; Kim & Jerjen 2015), the majority are most likely associated with the LMC (Jethwa et al. 2016).”
CONSTRAINTS ON MACHO DARK MATTER FROM COMPACT STELLAR SYSTEMS IN ULTRA-FAINT DWARF GALAXIES (2016, background): “The cluster’s observedMV = −3.5 thus implies a stellar mass of ∼2000 M⊙ at an age of 3 Gyr, or a mass of ∼6000 M⊙ at an age of 12 Gyr.”