ABSTRACT
Cross-correlation analysis of the thermal Sunyaev–Zel’dovich (tSZ) effect and weak gravitational lensing (WL) provides a powerful probe of cosmology and astrophysics of the intracluster ...medium. We present the measurement of the cross-correlation of tSZ and WL from Planck and Subaru Hyper-Suprime Cam. The combination enables us to study cluster astrophysics at high redshift. We use the tSZ-WL cross-correlation and the tSZ autopower spectrum measurements to place a tight constraint on the hydrostatic mass bias, which is a measure of the degree of non-thermal pressure support in galaxy clusters. With the prior on cosmological parameters derived from the analysis of the cosmic microwave background anisotropies by Planck and taking into account foreground contributions both in the tSZ autopower spectrum and the tSZ-WL cross-correlation, the hydrostatic mass bias is estimated to be $26.9^{+8.9}_{-4.4} {{\ \rm per\ cent}}$ ($68{{\ \rm per\ cent}}$ CL), which is consistent with recent measurements by mass calibration techniques.
We search for the lensing signal of massive filaments between 135 000 pairs of luminous red galaxies (LRGs) from the Sloan Digital Sky Survey. We develop a new estimator that cleanly removes the much ...larger shear signal of the neighbouring LRG haloes, relying only on the assumption of spherical symmetry. We consider two models: a ‘thick’-filament model constructed from ray-tracing simulations for Λ cold dark matter model, and a ‘thin’-filament model which models the filament by a string of haloes along the line connecting the two LRGs. We show that the filament lensing signal is in nice agreement with the thick simulation filament, while strongly disfavouring the thin model. The magnitude of the lensing shear due to the filament is below 10−4. Employing the likelihood ratio test, we find a 4.5σ significance for the detection of the filament lensing signal, corresponding to a null hypothesis fluctuation probability of 3 × 10−6. We also carried out several null tests to verify that the residual shear signal from neighbouring LRGs and other shear systematics are minimized.
We constrain the scaling relation between optical richness (λ) and halo mass (M) for a sample of Sloan Digital Sky Survey (SDSS) red-sequence Matched-filter Probabilistic Percolation (redMaPPer) ...galaxy clusters within the context of the Planck cosmological model. We use a forward modeling approach where we model the probability distribution of optical richness for a given mass, . To model the abundance and the stacked lensing profiles, we use an emulator specifically built to interpolate the halo mass function and the stacked lensing profile for an arbitrary set of halo mass and redshift, which is calibrated based on a suite of high-resolution N-body simulations. We apply our method to 8312 SDSS redMaPPer clusters with 20 ≤ λ ≤ 100 and 0.10 ≤ zλ ≤ 0.33 and show that the lognormal distribution model for , with four free parameters, well reproduces the measured abundances and lensing profiles simultaneously. The constraints are characterized by the mean relation, , with and (68% CL), where the pivot mass scale Mpivot = 3 × 1014 h−1 M , and the scatter with and . We find that a large scatter in halo masses is required at the lowest-richness bins (20 ≤ λ 30) in order to reproduce the measurements. Without such a large scatter, the model prediction for the lensing profiles tends to overestimate the measured amplitudes. This might imply a possible contamination of intrinsically low-richness clusters due to the projection effects. Such a low-mass halo contribution is significantly reduced when applying our method to the sample of 30 ≤ λ ≤ 100.
We assess the performance of a perturbation theory inspired method for inferring cosmological parameters from the joint measurements of galaxy-galaxy weak lensing (ΔΣ) and the projected galaxy ...clustering (wp). To do this, we use a wide variety of mock galaxy catalogs constructed based on a large set of N-body simulations that mimic the Subaru HSC-Y1 and SDSS galaxies and apply the method to the mock signals to address whether to recover the underlying true cosmological parameters in the mocks. We find that, as long as the appropriate scale cuts, 12 and 8h−1 Mpc for ΔΣ and wp, respectively, are adopted, a "minimal-bias" model using the linear bias parameter b1 alone and the nonlinear matter power spectrum can recover the true cosmological parameters (here focused on Ωm and σ8) to within the 68% credible interval, for all the mocks we study, including one in which an assembly bias effect is implemented. This is as expected if physical processes inherent in galaxy formation and evolution are confined to local, small scales below the scale cut and thus implies that real-space observables have an advantage in filtering out the impact of small-scale nonlinear effects in parameter estimation, compared to their Fourier-space counterparts. In addition, we find that a theoretical template including the higher-order bias contributions such as nonlinear bias parameter (b2) does not improve the cosmological constraints, but rather leads to a larger parameter bias compared to the baseline b1 method. Another nontrivial finding is that the cosmological parameters are not necessarily recovered, even when the model prediction is used as the input mock signals, as a consequence of marginalization or projection of asymmetric posterior distributions in a multidimensional parameter space, such as the case of the "banana-shaped" distribution in the (Ωm, σ8) plane. We also study the performance of alternative observables, Υ or Y statistic, where the same scale cut for both the weak lensing and the galaxy clustering can be employed thanks to their same sensitivity to the Fourier modes, but do not find a promising advantage of these statistics over the fiducial observables {ΔΣ, wp}.
We present significant evidence of halo assembly bias for SDSS redMaPPer galaxy clusters in the redshift range 0.1, 0.33. By dividing the 8,648 clusters into two subsamples based on the average ...member galaxy separation from the cluster center, we first show that the two subsamples have very similar halo mass of M_{200m}≃1.9×10^{14} h^{-1}M_{⊙} based on the weak lensing signals at small radii R≲10 h^{-1}Mpc. However, their halo bias inferred from both the large-scale weak lensing and the projected autocorrelation functions differs by a factor of ∼1.5, which is a signature of assembly bias. The same bias hypothesis for the two subsamples is excluded at 2.5σ in the weak lensing and 4.4σ in the autocorrelation data, respectively. This result could bring a significant impact on both galaxy evolution and precision cosmology.
Hyper Suprime-Cam: Camera dewar design Komiyama, Yutaka; Obuchi, Yoshiyuki; Nakaya, Hidehiko ...
Publications of the Astronomical Society of Japan,
01/2018, Letnik:
70, Številka:
SP1
Journal Article
Recenzirano
Abstract
This paper describes the detailed design of the CCD dewar and the camera system which is a part of the wide-field imager Hyper Suprime-Cam (HSC) on the 8.2 m Subaru Telescope. On the 1.°5 ...diameter focal plane (497 mm in physical size), 116 four-side buttable 2 k × 4 k fully depleted CCDs are tiled with 0.3 mm gaps between adjacent chips, which are cooled down to −100°C by two pulse tube coolers with a capability to exhaust 100 W heat at −100°C. The design of the dewar is basically a natural extension of Suprime-Cam, incorporating some improvements such as (1) a detailed CCD positioning strategy to avoid any collision between CCDs while maximizing the filling factor of the focal plane, (2) a spherical washers mechanism adopted for the interface points to avoid any deformation caused by the tilt of the interface surface to be transferred to the focal plane, (3) the employment of a truncated-cone-shaped window, made of synthetic silica, to save the back focal space, and (4) a passive heat transfer mechanism to exhaust efficiently the heat generated from the CCD readout electronics which are accommodated inside the dewar. Extensive simulations using a finite-element analysis (FEA) method are carried out to verify that the design of the dewar is sufficient to satisfy the assigned errors. We also perform verification tests using the actually assembled CCD dewar to supplement the FEA and demonstrate that the design is adequate to ensure an excellent image quality which is key to the HSC. The details of the camera system, including the control computer system, are described as well as the assembling process of the dewar and the process of installation on the telescope.
ABSTRACT We show that the projected number density profiles of Sloan Digital Sky Survey photometric galaxies around galaxy clusters display strong evidence for the splashback radius, a sharp halo ...edge corresponding to the location of the first orbital apocenter of satellite galaxies after their infall. We split the clusters into two subsamples with different mean projected radial distances of their members, , at fixed richness and redshift. The sample with smaller has a smaller ratio of the splashback radius to the traditional halo boundary than the subsample with larger , indicative of different mass accretion rates for these subsamples. The same subsamples were recently used by Miyatake et al. to show that their large-scale clustering differs despite their similar weak lensing masses, demonstrating strong evidence for halo assembly bias. We expand on this result by presenting a 6.6 difference in the clustering amplitudes of these samples using cluster-photometric galaxy cross-correlations. This measurement is a clear indication that halo clustering depends on parameters other than halo mass. If is related to the mass assembly history of halos, the measurement is a manifestation of the halo assembly bias. However, our measured splashback radii are smaller, while the strength of the assembly bias signal is stronger, than the predictions of collisionless Λ cold dark matter simulations. We show that dynamical friction, cluster mis-centering, or projection effects are not likely to be the sole source of these discrepancies. However, further investigations regarding unknown catastrophic weak lensing or cluster identification systematics are warranted.
The Hyper Suprime-Cam software pipeline Bosch, James; Armstrong, Robert; Bickerton, Steven ...
Publications of the Astronomical Society of Japan,
01/2018, Letnik:
70, Številka:
SP1
Journal Article
Recenzirano
Abstract
In this paper, we describe the optical imaging data processing pipeline developed for the Subaru Telescope’s Hyper Suprime-Cam (HSC) instrument. The HSC Pipeline builds on the prototype ...pipeline being developed by the Large Synoptic Survey Telescope’s Data Management system, adding customizations for HSC, large-scale processing capabilities, and novel algorithms that have since been reincorporated into the LSST codebase. While designed primarily to reduce HSC Subaru Strategic Program (SSP) data, it is also the recommended pipeline for reducing general-observer HSC data. The HSC pipeline includes high-level processing steps that generate coadded images and science-ready catalogs as well as low-level detrending and image characterizations.
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