1601.00115
Revisiting CFHTLenS cosmic shear: optimal E/B mode decomposition using COSEBIs and compressed COSEBIs
Asgari, Heymans, Blake, Harnois-Deraps, Schneider, Van Waerbeke
Present a re-analysis of the CFHTLenS WL survey using COSEBI (Complete orthogonal sets of E/B-mode integrals). COSEBIs provide a complete set of functions to efficiently separate E-modes from B-modes and hence allow for robust and stringent tests for systematic errors in the data. This analysis reveals significant B-modes on large angular scales that were not previously seen using the standard E/B decomposition analyses. Find that the significance of the B-modes is enhanced when the data is split by galaxy type and analyses in tomographic redshift bins. Adding tomographic bins to the analysis increases the number of COSEBIs modes, which results in less accurate estimation of the covariance matrix from a set of simulations. Also present the first compressed COSEBIs analysis of survey data, where the COSEBIs modes are optimally combined based on their sensitivity to cosmo parameters. In this tomographic COSEBIs analysis, find the B-modes to be consistent with zero when the full range of angular scales are considered.
1601.00160
A new method to measure galaxy bias by combining the density and weak lensing fields
Pujol, Chang, Gaztañaga, Amara, Refregier, Bacon, etc.
Present a new method to measure the redshift-dependent galaxy bias by combining information from the galaxy density field and the weak lensing field. This method is based on Amara+2012, where they use the galaxy density field to construct a bias-weighted convergence field kg. The main difference between Amara+2012 and the new implementations is that here, another way is presented to measure galaxy bias using tomography instead of bias parameterizations. The correlation between kg and the true lensing field k allows measurement of galaxy bias using different zero-lag correlations, such as <kgk>/<kk> or <kgkg>/<kgk>. This paper is the first that studies and systematically tests the robustness of this method in simulations. Use the MICE simulation suite, which includes a set of self-consistent N-body sims, lensing maps, and mock galaxy catalogues. Study the accuracy and systematic uncertainties associated with the implementation of the method, and the regime where it is consistent with the linear galaxy bias defined by projected 2PCF. Find that the method is consistent with linear bias at the precent level for scales larger than 30 arcmin, while nonlinearities appear at smaller scales. Also find that projection along the redshift direction can cause up to a 5% deviation between the different galaxy bias estimators. This measurement is a good complement to other measurements of bias, since it does not depend strongly on sigma8 as the 2PCF measurements. Apply this method to DES SV data in a follow-up paper.
1601.00329
The Dark Energy Survey: more than dark energy - an overview
DES collaboration
This overview article describes the legacy prospect and discovery potential of DES beyond cosmo studies, illustrating it with examples from the DES early data. DES is using a wide-field camera (DECam) on the 4m Blanco Telescope in Chile to image 5000 sq deg of the sky in 5 filters (grizY). By its completion the survey is expected to have generated a catalogue of 300 million galaxies with photometric redshifts and 100 million stars. In addition, a time-domain survey search over 27 sq deg is expected to yield a sample of thousands of SNe Ia and other transients. The ain goals of DES are to characterize DE and DM, and to test alternative models of gravity; these goals will be pursued by studying LSS, cluster counts, weak gravitational lensing and SNe Ia. However, DES also provides a rich data set which allows to study many other aspects of astrophysics. In this paper, focus on additional science with DES, emphasizing areas where the survey makes a difference with respect to other current surveys. The paper illustrate, using early data (from SV, and from the first, second and 3rd seasons of observations), what DES can tell about the solar system, the MW, galaxy evolution, quasars, and other topics. In addition, show that if the cosmological model is assume to be LCDM then important astrophysics can be deduced from the primary DES proves. Highlights from DES easy data include the discovery of 34 Trans Neptunian Objects, 17 dwarf satellites of the MW, one published z>6 quasar (and more confirmed) and two published superlumious SNe (and more confirmed).
1601.00405
Galaxy bias from the DES Science Verification data: combining galaxy density aps and weak lensing maps
Chang, Pujol, et al
Measure the redshift evolution of galaxy bias from a magnitude-limited galaxy sample by combining the galaxy density maps and weak lensing shear maps for a ~116 deg sq area of DES SV data. This method was first developed in Amara+2012 and later re-examined in a companion paper (Pujol et al) with rigorous simulation tests and analytical treatment of tomographic measurements. In this work, apply this method to the DES SV data and measure the galaxy bias for a magnitude-limited galaxy sample. Find the galaxy bias and 1 sigma error bars in 4 photo-z bins to be 1.33±0.18 (z=0.2-0.4), 1.19±0.23 (z=0.4-0.6), 0.99±0.36 (z=0.6-0.8), and 1.66±0.56 (z=0.8-1.0). These measurements are consistent at the 1-2 sigma level with measurements of the same dataset using galaxy clustering and cross-correlation of galaxies with CMB lensing. In addition, the method provides the only sigma8-independent constraint among the 3. Forward-model the main observational effects using mock galaxy catalogs by including shape noise, photo-z errors and masking effects. Show that the bias measurement from the data is consistent with that expected from simulations. With the forthcoming full DES data set, expect this method to provide additional constraints on the galaxy bias measurement from more traditional methods. Furthermore, in the process of the measurement, build up a 3d mass map that allows further exploration of the DM distribution and its relation to galaxy evolution.
1601.00621
The redMapPer galaxy cluster catalog from DES Science Verification data
Rykoff, et al
786 clusters with richness lambda>20 (roughly equivalent to M_500c>1e14 Msun/h_70) and 0.2<z<0.9.
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