Day 928

Monday.


1507.04752
The Stripe 82 Massive galaxy project II: stellar mass completeness of spectroscopic galaxy samples from the Baryon Oscillation Spectroscopic survey
Leauthaud, et al

BOSS: >1e6 galaxies at 1.5<z<0.7 over a volume of 15.3 Gpc^3 (9376 deg^2) -- providing an opportunity to study the most massive galaxy populations with vanishing sample variance.  However, BOSS samples are selected via complex color cuts that are optimized for cosmology studies, not galaxy science.  Supplement BOSS samples with photo-z from Stripe 82 Massive Galaxy Catalog and measure the total galaxy stellar mass function (SMF) at z~0.3 and z~0.55.  With the total SMF in hand, characterize the stellar mass completeness of BOSS samples.  The high-redshift CMASS ("constant mass") sample is significantly impacted by mass imcompeteness and is 80% complete at log10(M*/Msun)>11.6 only in the narrow redshift range z=[0.51,0.61].  The low redshift LOWZ sample is 80% complete at log10(M*/Msun)>11.6 for z=[0.15,0.43].  To construct mass complete samples at lower masses, spectroscopic samples nee to be significantly supplemented by photo-z.  This work will enable future studies to better utilize the BOSS samples for galaxy-formation science.


1507.04862
Enhancing the cosmic shear power spectrum
Simpson, Harnois-Déraps, Heymans, Jiminez, Verde

Applying a transformation to a non-Gaussian field can enhance the information content of the resulting PS, by reducing the correlations between Fourier modes.  In the context of WL, it has been shown that this gain in information content is significant compromised by the presence of shape noise.  Apply clipping to mock convergence fields, a technique which is known to be robust in the presence of noise and has been successfully applied to galaxy number density fields.  When analyzed in isolation the resulting convergence PS returns degraded constraints on cosmo parameters.  However, substantial gains can be achieved by performing a combined analysis of the PS derived from both the original and transformed fields.  Even in the presence of realistic levels of shape noise, demonstrate that this approach is capable of reducing the area of likelihood contours within the Omega_m-sigma8 plane by more than a factor of 3.