Day 801

Monday.

1412.1825
GREAT3 results I: systematic errors in shear estimation and the impact of real galaxy morphology
Mandelbaum, Rowe, et al

First results from GREAT3, which was divided into experiments to test 3 specific questions, and included simulated space- and ground-based data with constant or cosmologically-varying shear fields.  The simplest (control) experiment included parametric galaxies with a realistic distribution of S/N, size and ellipticity, and a complex PSF.  The other experiments tested the additional impact of realistic galaxy morphology, multiple exposure imaging, and the uncertainty about a spatially-varying PSF; the last 2 questions will be explored in Paper II.  The 24 participating teams competed to estimate lensing shears to within systematic error tolerances for upcoming Stage-IV DE surveys, making 1525 submissions overall.  GREAT3 saw considerable variety and innovation in the type of methods applied.  Several teams now meet or exceed the targets in many of the tests conducted (to within the statistical errors).  Conclude that the presence of realistic galaxy morphology in simulations changes shear calibration biases by ~1% for a wide range of methods.  Other effects such as truncation biases due to finite galaxy postage stamps, and the impact of galaxy type as measured by the Sersic index, are quantified for the first time.  Results generalize previous studies regarding sensitivities to galaxy size and S/N, and to PSF properties such as seeing and defocus.  Almost all methods' results support the simple model in which additive shear biases depend linearly on PSF ellipticity.

1412.1835
The MOSFIRE Deep Evolution Field (MOSDEF) survey: rest-frame optical spectroscopy for ~1500 H-selected galaxies at 1.37 < z < 3.8
Kriek, Shapley, ... Coil, et al

MOSDEF aims to obtain moderate-resolution (R=3000-3650) rest-frame optical spectra (~3700-7000A) for ~1500 galaxies at 1.37<z<3.80 in three well- studied CANDELS fields: AEGIS, COSMOS and GOODS-N.  Targets are selected in 3 z intervals: 1.37<z<1.70, 2.09<z<2.61, and 2.95<z<3.80, down to fixed H_AB( F160W) magnitudes of 24.0, 24.5, and 25.0, respectively, using the photometric and spectroscopic catalogs from the 3D-HST survey. Target both strong nebular emission lines (e.g., [OII], Hbeta, [OIII], 5008, Halpha, [NII] and [SII]) and stellar continuum and absorption features (e.g., Balmer lines, Ca-II H and K, Mob, 4000 A break).  Here, present an overview of the survey, the observational strategy, the data reduction and analysis, and the sample characteristics based on spectra obtained during the first 24 nights.  To date, completed 21 masks, obtaining spectra of 591 galaxies, which were serendipitously detected.  The MOSDEF galaxy sample includes unobscured star-forming, dusty SF, and quiescent galaxies and spans a wide range in stellar mass (1e9-11.5 Msun) and SFR (~0-1e4 Msun/yr).  The spectroscopically confirmed sample is roughly representative of an H-band limited galaxy sample at these redshifts.  With its large sample size, broad diversity in galaxy properties, and wealth of available ancillary data, MOSDEF will transform understanding of the stellar, gaseous, metal, dust and black hole content of galaxies during the time when the universe was most active.

1412.1839
Dissipative dark mater and the andromeda plane of satellites
Randall, Scholtz

Show that dissipative DM can potentially explain the large observed M/L ratio of the dwarf satellite galaxies that have been observed in the recently identified planar structure around Andromeda, which are thought to result from tidal forces during a galaxy merger.  Whereas dwarf galaxies created from ordinary disks would be dark matter poor, DM inside the galactic plane not only provides a source of DM, but one that is more readily bound due to the DM's lower velocity.  This initial N-body study shows that with a thin disk of DM inside the baryonic disk, M/L ratios as high as O(30) can be generated when tidal forces pull out patches of sizes similar to the scales of Toomre instabilities of the dark disk.  A full simulation will be needed to confirm this result.