beecee Posted March 2, 2018 Posted March 2, 2018 (edited) Unprecedentedly wide and sharp dark matter map March 2, 2018, Subaru Telescope Figure 1: 2 dimensional dark matter map estimated by weak lensing technique. The dark matter is concentrated in dense clumps. We can identify massive dark matter halos (indicated by oranges circles). The area shown in this figure is approximately 30 square degrees (a total of 160 square degrees were observed this time). The distribution map without the orange circles is available here. Credit: NAOJ/University of Tokyo A research team of multiple institutes, including the National Astronomical Observatory of Japan and University of Tokyo, released an unprecedentedly wide and sharp dark matter map based on the newly obtained imaging data by Hyper Suprime-Cam on the Subaru Telescope. The dark matter distribution is estimated by the weak gravitational lensing technique (Figure 1, Movie). The team located the positions and lensing signals of the dark matter halos and found indications that the number of halos could be inconsistent with what the simplest cosmological model suggests. This could be a new clue to understanding why the expansion of the Universe is accelerating. Read more at: https://phys.org/news/2018-03-unprecedentedly-wide-sharp-dark.html#jCp <<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> the paper: https://arxiv.org/pdf/1802.10290v1.pdf A large sample of shear selected clusters from the Hyper Suprime-Cam Subaru Strategic Program S16A wide field mass maps Abstract: We present the result of searching for clusters of galaxies based on weak gravitational lensing analysis of the ∼ 160 deg2 area surveyed by Hyper Suprime-Cam (HSC) as a Subaru Strategic Program. HSC is a new prime focus optical imager with a 1.5 diameter field of view on the 8.2- meter Subaru telescope. The superb median seeing on the HSC i-band images of 0.56 arcsec allows the reconstruction of high angular resolution mass maps via weak lensing, which is crucial for the weak lensing cluster search. We identify 65 mass map peaks with signal-tonoise (SN) ratio larger than 4.7, and carefully examine their properties by cross-matching the clusters with optical and X-ray cluster catalogs. We find that all the 39 peaks with SN> 5.1 have counterparts in the optical cluster catalogs, and only 2 out of the 65 peaks are probably false positives. The upper limits of X-ray luminosities from ROSAT All Sky Survey (RASS) imply Edited March 2, 2018 by beecee
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