KiDS+GAMA: cosmology constraints from a joint analysis of cosmic shear, galaxy–galaxy lensing, and angular clustering

Abstract

We present cosmological parameter constraints from a joint analysis of three cosmological probes: the tomographic cosmic shear signal in ∼450 deg 2 of data from the Kilo Degree Survey (KiDS), the galaxy-matter cross-correlation signal of galaxies from the Galaxies And Mass Assembly (GAMA) survey determined with KiDS weak lensing, and the angular correlation function of the same GAMA galaxies. We use fast power spectrum estimators that are based on simple integrals over the real-space correlation functions, and show that they are practically unbiased over relevant angular frequency ranges. We test our full pipeline on numerical simulations that are tailored to KiDS and retrieve the input cosmology. By fitting different combinations of power spectra, we demonstrate that the three probes are internally consistent. For all probes combined, we obtain S 8 ≡ σ 8 √ m /0.3 = 0.800 +0.029 −0.027 , consistent with Planck and the fiducial KiDS-450 cosmic shear correlation function results. Marginalizing over wide priors on the mean of the tomographic redshift distributions yields consistent results for S 8 with an increase of 28 per cent in the error. The combination of probes results in a 26 per cent reduction in uncertainties of S 8 over using the cosmic shear power spectra alone. The main gain from these additional probes comes through their constraining power on nuisance parameters, such as the galaxy intrinsic alignment amplitude or potential shifts in the redshift distributions, which are up to a factor of 2 better constrained compared to using cosmic shear alone, demonstrating the value of large-scale structure probe combination.

When galaxies align: intrinsic alignments of the progenitors of elliptical galaxies in the Horizon-AGN simulation

“…We thus use two sets of simulation outputs: a coarsely sampled set at z = {0.06, 1, 2, 3} that can give us insights into the broad redshift evolution of the alignment signal, and a more refined set at low redshift, with 6 snapshots spanning the range 0 < z < 0.7 where we expect a steep increase in the fraction of ellipticals according to our previous work (Chisari et al 2016;Dubois et al 2016;Martin et al 2018a). Note that the tidal field eigenvectors and their eigenvalues, are closely connected to the classification of the cosmic web into filaments, walls and knots of the large-scale structure (Zel'dovich 1970;Bond et al 1996;Hahn et al 2007;Libeskind et al 2018). For the purpose of this work, it suffices to recall that in filaments, the spine of the filament follows the direction of v 1 .…”

“…Observational evidence of this phenomenon was first identified in the pioneering work of Binggeli (1982) in an analysis of Brightest Cluster Galaxies in the Abell sample of clusters. Since then, many works have shown a tendency for luminous red galaxies to align radially towards overdensities in the matter field Mandelbaum et al 2006;Hirata et al 2007;Joachimi et al 2011;van Uitert & Joachimi 2017;Johnston et al 2018), with more luminous or massive galaxies displaying a stronger signal. There is also evidence of them having a preferential orientation with respect ⋆ E-mail: n.e.chisari@uu.nl to filaments in the cosmic structure, aligning their minor axes in the direction perpendicular to the filament (Tempel & Libeskind 2013) or their major axes parallel to them .…”

“…The large-scale tidal field indeed generates on the one hand tidal stretching (Catelan et al 2001) and on the other hand, tidal torquing (see Schäfer 2009 for a review) spinning up haloes and galaxies in a cosmic-web dependent way (Codis et al 2015b). With the emergence of weak gravitational lensing surveys, and their application to precision cosmology (Huff et al 2014;Troxel et al 2018;van Uitert et al 2018;Joudaki et al 2018), intrinsic correlations between galaxy shapes ("intrinsic alignments") were identified as a potential contaminant to the lensing signal (Brown et al 2002;Hirata & Seljak 2004). (For an overview of intrinsic alignments, see Joachimi et al 2015;Troxel & Ishak 2015.…”

Density split statistics: Cosmological constraints from counts and lensing in cells in DES Y1 and SDSS data

“…In combination with cosmic microwave background (CMB) and other geometric data, they are stringent tests of ΛCDM predictions on the evolution of structure over cosmic time [1][2][3][4][5]. Ostensibly, larger studies of this kind are the primary goal of the upcoming ambitious ground-based and spacebased surveys by Euclid, LSST, and WFIRST.…”

On the road to per cent accuracy – II. Calibration of the non-linear matter power spectrum for arbitrary cosmologies

“…The landscape of ΛCDM extensions is exceptionally vast, and in this work we only consider a family of f (R) gravity theories (Hu & Sawicki 2007) and massive neutrino cosmologies (Lesgourgues & Pastor 2006), both with a ΛCDM background. However, with little or no modification our methodology (see Section 3) can be applied to a much broader class of models, including non-standard dark matter candidates (Marsh & Silk 2014;Schneider 2015;Cyr-Racine et al 2016;Marsh 2016;Poulin et al 2016;Hložek et al 2017;Dakin et al 2019;Thomas et al 2019), extra relativistic degrees of freedom (Baumann et al 2018), and Horndeski theories (Zumalacárregui et al 2017).…”