We derive updated constraints on the integrated Sachs-Wolfe (ISW) effect through cross-correlation of the cosmic microwave background with galaxy surveys. We improve with respect to similar previous ...analyses in several ways. First, we use the most recent versions of extragalactic object catalogs, SDSS DR12 photometric redshift (photo-z) and 2MASS Photo-z data sets, as well as those employed earlier for ISW, SDSS QSO photo-z and NVSS samples. Second, we use for the first time the WISE × SuperCOSMOS catalog, which allows us to perform an all-sky analysis of the ISW up to z∼0.4. Third, thanks to the use of photo-zs, we separate each data set into different redshift bins, deriving the cross-correlation in each bin. This last step leads to a significant improvement in sensitivity. We remove cross-correlation between catalogs using masks which mutually exclude common regions of the sky. We use two methods to quantify the significance of the ISW effect. In the first one, we fix the cosmological model, derive linear galaxy biases of the catalogs, and then evaluate the significance of the ISW using a single parameter. In the second approach we perform a global fit of the ISW and of the galaxy biases varying the cosmological model. We find significances of the ISW in the range 4.7–5.0σ thus reaching, for the first time in such an analysis, the threshold of 5σ. Without the redshift tomography we find a significance of ∼4.0σ, which shows the importance of the binning method. Finally we use the ISW data to infer constraints on the dark energy redshift evolution and equation of state. We find that the redshift range covered by the catalogs is still not optimal to derive strong constraints, although this goal will be likely reached using future datasets such as from Euclid, LSST, and SKA.
ABSTRACT
We cross-correlate maps of the thermal Sunyaev–Zeldovich (tSZ) Compton-y parameter published by Planck with the projected distribution of galaxies in a set of low-redshift tomographic bins. ...We use the nearly full-sky 2MASS Photometric Redshift and WISE × SuperCOSMOS public catalogues, covering the redshift range z ≲ 0.4. Our measurements allow us to place constraints on the redshift dependence of the mass–observable relation for tSZ cluster count analyses in terms of the so-called hydrostatic mass bias parameter $1-b_{\scriptscriptstyle \rm H}$. These results can also be interpreted as measurements of the bias-weighted average gas pressure 〈bPe〉 as a function of redshift, a quantity that can be related to the thermodynamics of gas inside haloes and used to constrain energy injection processes. We measure $1-b_{\scriptscriptstyle \rm H}$ with $\sim \!13{{\ \rm per\ cent}}$ precision in six equispaced redshift bins, and find no evidence for a redshift-dependent mass bias parameter, in agreement with previous analyses. Our mean value of $1-b_{\scriptscriptstyle \rm H}= 0.59\pm 0.03$ is also in good agreement with the one estimated by the joint analysis of Planck cluster counts and cosmic microwave background anisotropies. Our measurements of 〈bPe〉, at the level of $\sim \!10{{\ \rm per\ cent}}$ in each bin, are the most stringent constraints on the redshift dependence of this parameter to date, and agree well both with previous measurements and with theoretical expectations from shock-heating models.
We present a joint cosmological analysis of weak gravitational lensing observations from the Kilo-Degree Survey (KiDS-1000), with redshift-space galaxy clustering observations from the Baryon ...Oscillation Spectroscopic Survey (BOSS) and galaxy-galaxy lensing observations from the overlap between KiDS-1000, BOSS, and the spectroscopic 2-degree Field Lensing Survey. This combination of large-scale structure probes breaks the degeneracies between cosmological parameters for individual observables, resulting in a constraint on the structure growth parameter
S
8
= σ
8
√(Ω
m
/0.3) = 0.766
−0.014
+0.020
, which has the same overall precision as that reported by the full-sky cosmic microwave background observations from
Planck
. The recovered
S
8
amplitude is low, however, by 8.3 ± 2.6% relative to
Planck
. This result builds from a series of KiDS-1000 analyses where we validate our methodology with variable depth mock galaxy surveys, our lensing calibration with image simulations and null-tests, and our optical-to-near-infrared redshift calibration with multi-band mock catalogues and a spectroscopic-photometric clustering analysis. The systematic uncertainties identified by these analyses are folded through as nuisance parameters in our cosmological analysis. Inspecting the offset between the marginalised posterior distributions, we find that the
S
8
-difference with
Planck
is driven by a tension in the matter fluctuation amplitude parameter,
σ
8
. We quantify the level of agreement between the cosmic microwave background and our large-scale structure constraints using a series of different metrics, finding differences with a significance ranging between ∼3
σ
, when considering the offset in
S
8
, and ∼2
σ
, when considering the full multi-dimensional parameter space.
We present cosmological constraints from a cosmic shear analysis of the fourth data release of the Kilo-Degree Survey (KiDS-1000), which doubles the survey area with nine-band optical and ...near-infrared photometry with respect to previous KiDS analyses. Adopting a spatially flat standard cosmological model, we find
S
8
=
σ
8
(Ω
m
/0.3)
0.5
= 0.759
−0.021
+0.024
for our fiducial analysis, which is in 3
σ
tension with the prediction of the
Planck
Legacy analysis of the cosmic microwave background. We compare our fiducial COSEBIs (Complete Orthogonal Sets of E/B-Integrals) analysis with complementary analyses of the two-point shear correlation function and band power spectra, finding the results to be in excellent agreement. We investigate the sensitivity of all three statistics to a number of measurement, astrophysical, and modelling systematics, finding our
S
8
constraints to be robust and dominated by statistical errors. Our cosmological analysis of different divisions of the data passes the Bayesian internal consistency tests, with the exception of the second tomographic bin. As this bin encompasses low-redshift galaxies, carrying insignificant levels of cosmological information, we find that our results are unchanged by the inclusion or exclusion of this sample.
Key cosmological applications require the three-dimensional (3D) galaxy distribution on the entire celestial sphere. These include measuring the gravitational pull on the Local Group, estimating the ...large-scale bulk flow, and testing the Copernican principle. However, the largest all-sky redshift surveys-the 2MASS Redshift Survey and IRAS Point Source Catalog Redshift Survey-have median redshifts of only z = 0.03 and sample the very local universe. All-sky galaxy catalogs exist that reach much deeper-SuperCOSMOS in the optical, the Two Micron All Sky Survey (2MASS) in the near-IR, and WISE in the mid-IR-but these lack complete redshift information. At present, the only rapid way toward larger 3D catalogs covering the whole sky is through photometric redshift techniques. The all-sky photo-z catalogs, with a median z ~ 0.1 for the 2MPZ, and significantly deeper for future WISE-based samples, will be the largest and most complete of their kind for the foreseeable future.
Context. The Kilo-Degree Survey (KiDS) is an ongoing optical wide-field imaging survey with the OmegaCAM camera at the VLT Survey Telescope. It aims to image 1500 square degrees in four filters ...(ugri). The core science driver is mapping the large-scale matter distribution in the Universe, using weak lensing shear and photometric redshift measurements. Further science cases include galaxy evolution, Milky Way structure, detection of high-redshift clusters, and finding rare sources such as strong lenses and quasars. Aims. Here we present the third public data release and several associated data products, adding further area, homogenized photometric calibration, photometric redshifts and weak lensing shear measurements to the first two releases. Methods. A dedicated pipeline embedded in the Astro-WISE information system is used for the production of the main release. Modifications with respect to earlier releases are described in detail. Photometric redshifts have been derived using both Bayesian template fitting, and machine-learning techniques. For the weak lensing measurements, optimized procedures based on the THELI data reduction and lensfit shear measurement packages are used. Results. In this third data release an additional 292 new survey tiles (≈300 deg2) stacked ugri images are made available, accompanied by weight maps, masks, and source lists. The multi-band catalogue, including homogenized photometry and photometric redshifts, covers the combined DR1, DR2 and DR3 footprint of 440 survey tiles (44 deg2). Limiting magnitudes are typically 24.3, 25.1, 24.9, 23.8 (5σ in a 2′′ aperture) in ugri, respectively, and the typical r-band PSF size is less than 0.7′′. The photometric homogenization scheme ensures accurate colours and an absolute calibration stable to ≈2% for gri and ≈3% in u. Separately released for the combined area of all KiDS releases to date are a weak lensing shear catalogue and photometric redshifts based on two different machine-learning techniques.
We constrain the luminosity and redshift dependence of the intrinsic alignment (IA) of a nearly volume-limited sample of luminous red galaxies selected from the fourth public data release of the ...Kilo-Degree Survey (KiDS-1000). To measure the shapes of the galaxies, we used two complementary algorithms, finding consistent IA measurements for the overlapping galaxy sample. The global significance of IA detection across our two independent luminous red galaxy samples, with our favoured method of shape estimation, is ∼10.7
σ
. We find no significant dependence with redshift of the IA signal in the range 0.2 <
z
< 0.8, nor a dependence with luminosity below
L
r
≲ 2.9 × 10
10
h
−2
L
r
, ⊙
. Above this luminosity, however, we find that the IA signal increases as a power law, although our results are also compatible with linear growth within the current uncertainties. This behaviour motivates the use of a broken power law model when accounting for the luminosity dependence of IA contamination in cosmic shear studies.
Intrinsic galaxy alignments are a source of bias for weak lensing measurements as well as a tool for understanding galaxy formation and evolution. In this work, we measure the alignment of shapes of ...satellite galaxies, in galaxy groups, with respect to the brightest group galaxy (BGG), as well as alignments of the BGG shape with the satellite positions, using the highly complete Galaxy And Mass Assembly (GAMA) spectroscopic survey and deep imaging from the Kilo Degree Survey. We control systematic errors with dedicated image simulations and measure accurate shapes using the DEIMOS shape measurement method. We find a significant satellite radial alignment signal, which vanishes at large separations from the BGG. We do not identify any strong trends of the signal with galaxy absolute magnitude or group mass. The alignment signal is dominated by red satellites. We also find that the outer regions of galaxies are aligned more strongly than their inner regions, by varying the radial weight employed during the shape measurement process. This behaviour is evident for both red and blue satellites. BGGs are also found to be aligned with satellite positions, with this alignment being stronger when considering the innermost satellites, using red BGGs and the shape of the outer region of the BGG. Lastly, we measure the global intrinsic alignment signal in the GAMA sample for two different radial weight functions and find no significant difference.
The physics of gravity on cosmological scales affects both the rate of assembly of large-scale structure and the gravitational lensing of background light through this cosmic web. By comparing the ...amplitude of these different observational signatures, we can construct tests that can distinguish general relativity from its potential modifications. We used the latest weak gravitational lensing dataset from the Kilo-Degree Survey, KiDS-1000, in conjunction with overlapping galaxy spectroscopic redshift surveys, BOSS and 2dFLenS, to perform the most precise existing amplitude-ratio test. We measured the associated
E
G
statistic with 15 − 20% errors in five Δ
z
= 0.1 tomographic redshift bins in the range 0.2 <
z
< 0.7 on projected scales up to 100
h
−1
Mpc. The scale-independence and redshift-dependence of these measurements are consistent with the theoretical expectation of general relativity in a Universe with matter density Ω
m
= 0.27 ± 0.04. We demonstrate that our results are robust against different analysis choices, including schemes for correcting the effects of source photometric redshift errors, and we compare the performance of angular and projected galaxy-galaxy lensing statistics.
Abstract
We report the discovery of a potentially major supercluster that extends across the Galactic plane in the constellation of Vela, at a mean recessional velocity of ∼18 000 km s−1. Recent ...multiobject spectroscopic observations of this Vela supercluster (VSCL), using AAOmega+2dF and the Southern African Large Telescope, confirm an extended galaxy overdensity in the Zone of Avoidance (ZOA) located where residual bulk flows predict a considerable mass excess. We present a preliminary analysis of ∼4500 new spectroscopic galaxy redshifts obtained in the ZOA centred on the Vela region (
$l = 272{^{\circ}_{.}}5 \pm 20^\circ , b = 0^\circ \pm 10^\circ$
). The presently sparsely sampled data set traces an overdensity that covers
$25^\circ$
in Galactic longitude on either side of the Galactic plane, suggesting an extent of 25 × 20 deg2, corresponding to ∼ 115 × 90 h
70 Mpc at the supercluster redshift. In redshift space, the overdensity appears to consist of two merging wall-like structures, interspersed with clusters and groups. Both the velocity histogram and the morphology of the multibranching wall structure are consistent with a supercluster classification.
$K_{\rm s}^{\rm o}$
galaxy counts show an enhancement of ∼1.2 over the survey area for galaxies brighter than
$M_{K}^{\ast }$
at the VSCL distance, and a galaxy overdensity of δ = 0.50–0.77 within a photometric redshift shell around the VSCL, when compared with various Two Micron All-Sky Survey samples. Taking account of selection effects, the VSCL is estimated to contribute
$v_\mathrm{LG} \gtrsim 50$
km s−1 to the motion of the Local Group.
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