We use high-quality Subaru/Suprime-Cam imaging data to conduct a detailed weak-lensing study of the distribution of dark matter in a sample of 30 X-ray luminous galaxy clusters at 0.15 ≤ z ≤ 0.3. A weak-lensing signal is detected at high statistical significance in each cluster, the total signal-to-noise ratio of the detections ranging from 5 to 13. Comparing spherical models to the tangential distortion profiles of the clusters individually, we are unable to discriminate statistically between singular isothermal sphere (SIS) and Navarro Frenk & White (NFW) models. However when the tangential distortion profiles are combined and then models are fitted to the stacked profile, the SIS model is rejected at 6σ and 11σ, respectively, for low (M vir < 6 × 10 14 h −1 M ⊙ ) and high (M vir > 6 × 10 14 h −1 M ⊙ ) mass bins. We also use the individual cluster NFW model fits to investigate the relationship between cluster mass and concentration, finding that concentration (c vir ) decreases with increasing cluster mass (M vir ). The best-fit c vir − M vir relation is: c vir (M vir ) = 8.75 +4.13 −2.89 × (M vir /10 14 h −1 M ⊙ ) α with α ≈ −0.40 ± 0.19: i.e. a non-zero slope is detected at 2σ significance. This relation gives a concentration of c vir = 3.48 +1.65 −1.15 for clusters with M vir = 10 15 h −1 M ⊙ , which is inconsistent at 4σ significance with the values of c vir ∼ 10 reported for strong-lensing-selected clusters. We find that the measurement error on cluster mass is smaller at higher over-densities ∆ ≃ 500 − 2000, than at the virial over-density ∆ vir ≃ 110; typical fractional errors at ∆ ≃ 500 − 2000 are improved to σ(M ∆ )/M ∆ ≃ 0.1 − 0.2 compared with 0.2-0.3 at ∆ vir . Furthermore, comparing the 3D spherical mass with the 2D cylinder mass, obtained from the aperture mass method at a given aperture radius θ ∆ , reveals M 2D (< θ ∆ )/M 3D (< r ∆ = D l θ ∆ ) ≃ 1.46 and 1.32 for ∆ = 500 and ∆ vir , respectively. The amplitude of this offset agrees well with that predicted by integrating an NFW model of cluster-scale halos along the line-of-sight.

Subaru observations of A1689 (z = 0.183) are used to derive an accurate, model-independent mass profile for the entire cluster, r < ∼ 2Mpc/h, by combining magnification bias and distortion measurements. The projected mass profile steepens quickly with increasing radius, falling away to zero at r ∼ 1.0Mpc/h, well short of the anticipated virial radius. Our profile accurately matches onto the inner profile, r < ∼ 200kpc/h, derived from deep HST/ACS images. The combined ACS and Subaru information is well fitted by an NFW profile with virial mass, (1.93 ± 0.20) × 10 15 M ⊙ , and surprisingly high concentration, c vir = 13.7 +1.4 −1.1 , significantly larger than theoretically expected (c vir ≃ 4), corresponding to a relatively steep overall profile. A slightly better fit is achieved with a steep power-law model, d logΣ(θ)/d logθ ≃ −3, with a core θ c ≃ 1. ′ 7 (r c ≃ 210kpc/h), whereas an isothermal profile is strongly rejected. These results are based on a reliable sample of background galaxies selected to be redder than the cluster E/S0 sequence. By including the faint blue galaxy population a much smaller distortion signal is found, demonstrating that blue cluster members significantly dilute the true signal for r < ∼ 400kpc/h. This contamination is likely to affect most weak lensing results to date.

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DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) is the future Japanese space gravitational wave antenna. DECIGO is expected to open a new window of observation for gravitational wave astronomy especially between 0.1 Hz and 10 Hz, revealing various mysteries of the universe such as dark energy, formation mechanism of supermassive black holes, and inflation of the universe. The pre-conceptual design of DECIGO consists of three drag-free spacecraft, whose relative displacements are measured by a differential Fabry-Perot Michelson interferometer. We plan to launch two missions, DECIGO pathfinder and pre-DECIGO first and finally DECIGO in 2024.

DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) is the future Japanese space gravitational wave antenna. It aims at detecting various kinds of gravitational waves between 1 mHz and 100 Hz frequently enough to open a new window of observation for gravitational wave astronomy. The pre-conceptual design of DECIGO consists of three drag-free satellites, 1000 km apart from each other, whose relative displacements are measured by a Fabry–Perot Michelson interferometer. We plan to launch DECIGO in 2024 after a long and intense development phase, including two pathfinder missions for verification of required technologies.

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We present complete constraints imposed from observations of the cosmic microwave background radiation (CMBR) on the chaotic inflationary scenario with a nonminimally coupled inflaton field proposed by Fakir and Unruh (FU). Our constraints are complete in the sense that we investigate both the scalar density perturbation and the tensor gravitational wave in the Jordan frame, as well as in the Einstein frame. This makes the constraints extremely strong without any ambiguities due to the choice of frames. We find that the FU scenario generates tiny tensor contributions to the CMBR relative to chaotic models in minimal coupling theory, in spite of its spectral index of scalar perturbation being slightly tilted. This means that the FU scenario will be excluded if any tensor contributions to CMBR are detected by the forthcoming satellite missions. Conversely, if no tensor nature is detected despite the tilted spectrum, a minimal chaotic scenario will be hard to explain and the FU scenario will be supported. PACS number(s): 04.50.+h, 98.70.Vc, 98.80.Cq