Day 1336

Thursday.

1711.02677
Scale dependence of galaxy biasing investigated by weak gravitational lensing: an assessment using semi-analytic galaxies and simulated lensing data
Simon, Hilbert

Galaxies are biased tracers of the matter density on cosmological scales.  For future tests of galaxy models, refine and assess a method to measure galaxy biasing as function of physical scale k with WL.  This method enables reconstruction of the galaxy bias factor b(k) as well as the galaxy-matter correlation r(k) on physical scales between 0.01 h/Mpc <~ k <~ 10 h/Mpc for redshift-binned lens galaxies below z <~0.6.  In the refinement, account for an intrinsic alignment of source ellipticities, and correct for the lensing magnification of the angular number density of the lens galaxies to improve the accuracy of the reconstructed r(k).  For simulated data, the reconstructions achieve an accuracy of 3-7% (68% CL) over the above k-range for a survey area and a typical depth of contemporary ground-based surveys.  Realistically the accuracy is, however, probably reduced to about 10-15%, mainly by systematic errors in the assumed intrinsic source alignments, the fiducial cosmology, and the z distributions of lens and source galaxies (in that order).  Furthermore, the reconstruction technique employs physical templates for b(k) and r(k) that elucidate the impact of central galaxies and the halo-occupation statistics of satellite galaxies on the scale-dependence of galaxy bias, which is discussed in the paper.  In a first demonstration, apply this method to previous measurements in the Garching-Bonn-Deep Survey and give a physical interpretation of the lens population.


1711.02780
Mining the Kilo-Degree Survey for solar system objects
Mahlke, et al

The search for minor bodies in the solar system promises insights into its formation history.  Wide imaging surveys offer the opportunity to serendipitously discover and identify these traces of planetary formation and evolution.  Aim to present a method to acquire position, photometry, and proper motion measurements of solar system objects in surveys using dithered image sequences.  The application of this method on KiDS is demonstrated.  Optical images of 346 sq deg fields of the sky are searched in up to 4 filters using the AstrOmatic software suite to reduce the pixel to catalog data.  The solar system objects within the acquired sources are selected based on a set of criteria depending on their number of observation, motion, and size.  The Virtual Observatory SkyBoT tool is used to identify known objects.  Observed 20,221 SSO candidates, with an estimate false-positive content of less than 0.05%.  Of these SSO candidates, 53.4% are identified by  SkyBoT.  KiDS can detect previously unknown SSOs because of its depth and coverage at high ecliptic altitude, including parts of the Souther Hemisphere.  Thus, expect the large fraction of the 46.6% of unidentified objects to be truly new SSOs.  The method is applicable to a variety of dithered surveys such as DES, LSST, and Euclid.  It offers a quick and easy-to-implement search for solar system objects.  SkyBoT can then be used to estimate the completeness of the recovered sample.