1702.08449
First data release of the Hyper Suprime-Cam Subaru Strategic Program
Aihira, et al
The HSC-SSP is a 3-layered imaging survey aimed at addressing some of the most outstanding questions in astronomy today, including the nature of dark matter and dark energy. The survey has been awarded 300 nights of observing time at Subaru. The survey started in March 2014. This paper presents the first public data release of HSC-SSP. This release includes data taken in the first 1.7 years of observations (61.5 nights) and each of the Wide, Deep, and UltraDeep layers covers about 108, 26, and 4 square degrees down to depths of i~26.4, ~26.5, and ~27.2 mag, respectively (5 sigma for point sources). All the layers are observed in 5 broad-bands (grizy) and the Deep and UltraDeep layers are observed in narrow-bands as well. Achieve an impressive image quality of 0.6" in the i-band in the Wide layer. Show that 1-2% PSF photometry (rms) both internally and externally (against Pan-STARRS1) is achieved, and ~10mas and ~40mas internal and external astrometric accuracy, respectively. Both the calibrated images and catalogs are made available to the community through dedicated user interfaces and database servers. In addition to the pipeline products, also provide value-added products such as photometric redshifts and a collection of public spectroscopic redshifts. Detailed descriptions of all the data can be found online. The data release website is hsc-release.mtk.nao.ac.jp.
1702.08485
The weak lensing masses of filaments between luminous red galaxies
Epps, Hudson
In the standard model of non-linear structure formation, a cosmic web of dark-matter dominated filaments connects dark matter also. In this paper, stack the weak lensing signal of an ensemble of filaments between groups and clusters of galaxies. Specifically, detect the weak lensing signal, using CFHTLenS galaxy ellipticities, from stacked filaments between SDSS-III/BOSS luminous red galaxies (LRGs). As a control, compare the physical LRG pairs with projected LRG pairs that are more widely separated in redshift space. Detect the excess filament mass density in the projected pairs at the 5 sigma level, finding a mass of (1.6±0.3)e13 Msun for a stacked filament region 7.1 Mpc/h long and 2.5 Mpc/h wide. This filament signal is compared with a model based on the 3-pt galaxy-galaxyconvergence correlation function, as developed in Clampitt, Jain & Takada (2014), yielding reasonable agreement.
1702.08614
Testing redMaPPer centering probabilities using galaxy clustering and galaxy-galaxy lensing
Hikage, Mandelbaum, Leauthaud, Rozo, Rykoff
Galaxy cluster centering is one of the key issues for precision cosmology studies using galaxy surveys. The redMaPPer estimates the centering probability of member galaxies from photometric information; however, the centering algorithm has not previously been well-tested. Test the centering probabilities of redMaPPer cluster catalog using the projected cross correlation between redMaPPer clusters with photometric red galaxies and galaxy-galaxy lensing. Focus on the subsample of redMaPPer clusters in which the redMaPPer central galaxies (RMCGs) are not the brightest member galaxies (BMEM) and both of them have spectroscopic redshift. This subsample represents nearly 10% of the whole cluster sample. Also make a "High Pcen" sample where the central probability of RMCGs is larger than 99% to be used as a reference sample of central galaxies. Find a clear difference in the cross-correlation measurements between RMCGs and BMEMs, and the estimated centering probability is 74±10% for RMCGs and 13±4% for BMEMs in the sample. These values are in agreement with the central probability values reported by redMaPPer (75% for RMCG and 10% for BMEMs) within 1 sigma. The analysis provides a strong consistency test of the redMaPPer centering probabilities. The results suggest that redMaPPer centering probabilities are reliably estimated, and that the brightest galaxy in the cluster is not always the central galaxy.
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