Day 1078

Wednesday.

1604.01050
Redshift weights for Baryon Acoustic Oscillations : application to mock galaxy catalogs
Zhu, Padmanabhan, White, Ross, Zhao

Large z surveys capable of measuring the BAO signal have proven to be a effective way of measuring the distance-redshift relation from BAO measurements without splitting the sample into redshift bins.  Building off the work in Zhu+2015, develop a technique to directly constrain the distance-redshift relation from BAO measurements without splitting the sample into redshift bins.  Parameterize the distance-redshift relation, relative to a fiducial model, as a quadratic expansion.  Measure its coefficients and reconstruct the distance-redshift relation from the expansion.  Apply the z weighting technique in Zhu+2015 to the clustering of galaxies from 1000 QuickPM (QPM) mock sims after reconstruction and achieve a 0.75% measurement of the angular diameter distance D_A at z=0.64 and the same precision for Hubble parameter H at z=0.29.  These QPM mock catalogs are designed to mimic the clustering and noise level of BOSS DR12.  Compress the correlation functions in the redshift direction onto a set of weighted correlation functions.  These estimators give unbiased D_A and H measurements at all redshifts within the range of the combined sample.  Demonstrate the effectiveness of redshift weighting in improving the distance and Hubble parameter estimates.  Instead of measuring at a single 'effective' redshift as in traditional analyses, report the D_A and H measurements at all redshifts.  The measured fractional error of D_A ranges from 1.53% at z=0.2 to 0.75% at z=0.64.  The fractional error of H ranges from 0.85% at z=0.29 to 2.45% at z=0.7.  The measurements are consistent with a Fisher forecast to within 10% to 20% depending on the pivot redshift.  Further show the results are robust against the choice of fiducial cosmologies, galaxy bias models, and RSD streaming parameters.


1604.01051
Photometric selection of a luminous red galaxy catalog with $z\geq0.55$
Núñez, Spergel, Ho

Present development of photometrically selected LRG catalog at z>0.55.  LRG candidates are selected using IR/optical color-color cuts, optimized using ROC curve analysis, with optical data from SDSS and IR data rom "unWISE" forced photometry derived from WISE.  The catalog contains 16M objects, selected over the full SDSS DR10 footprint.  The z distribution of the resulting catalogs is estimated using spec-z from DEEP2 and COSMOS.  Restfram U-B colors from DEEP2 are used to estimate LRG selection efficiency.  In DEEP2, the resulting catalog has average redshift z=0.65, with sigma=2.0 and average rest frame U-B=1.0, with sigma=0.27.  In COSMOS, the resulting catalog has average redshift z=0.60, with sigma=1.8.  Also for 35% contamination from bluer galaxies, however anticipate these to be massive galaxies in the targeted z range that will be equally cosmologically useful.  Only an estimated 6% of selected objects are bluer sources with z<0.55.  Stellar contamination is estimated to be 1.8%.