The Buzzard Flock: Dark Energy Survey Synthetic Sky Catalogs

We present a suite of 18 synthetic sky catalogsdesigned to support science analysis of galaxiesin the Dark Energy Survey Year 1 (DES Y1) data. For each catalog, we use a computationally efficient empirical approach, ADDGALS, to embed galaxieswithin light-coneoutputs of three dark matter simulations that resolve halos with masses above ~5x10^12 h^-1 m_sun at z <= 0.32 and 10^13 h^-1 m_sun at z~2. The embedding method is tuned to match the observed evolution of galaxycounts at different luminosities as well as the spatial clustering of the galaxypopulation. Galaxiesare lensed by matter along the line of sight --- including magnification, shear, and multiple images --- using CALCLENS, an algorithm that calculates shear with 0.42 arcmin resolution at galaxypositions in the full catalog. The catalogspresented here, each with the same LCDM cosmology (denoted Buzzard), contain on average 820 million galaxiesover an area of 1120 square degreeswith positions, magnitudes, shapes, photometric errors, and photometric redshiftestimates. We show that the weak-lensing shear catalog, redMaGiC galaxy catalogsand redMaPPer cluster catalogsprovide plausible realizations of the same catalogsin the DES Y1 data by comparing their magnitude, color and redshift distributions, angular clustering, and mass-observable relations, making them useful for testing analyses that use these samples. We make public the galaxysamples appropriate for the DES Y1 data, as well as the data vectors used for cosmology analyses on these simulations.