Cluster Cosmology Constraints from the 2500 deg² SPT-SZ Survey: Inclusion of Weak Gravitational Lensing Data from Magellan and the Hubble Space Telescope

Abstract

We derive cosmological constraints using a galaxy cluster sample selected from the 2500 deg 2 SPT-SZ survey. The sample spans the redshift range 0.25<z<1.75 and contains 343 clusters with SZ detection significance ξ>5. The sample is supplemented with optical weak gravitational lensing measurements of 32 clusters with 0.29<z<1.13 (from Magellan and Hubble Space Telescope) and X-ray measurements of 89 clusters with 0.25<z<1.75 (from Chandra). We rely on minimal modeling assumptions: (i) weak lensing provides an accurate means of measuring halo masses, (ii) the mean SZ and X-ray observables are related to the true halo mass through power-law relations in mass and dimensionless Hubble parameter E(z) with a priori unknown parameters, and (iii) there is (correlated, lognormal) intrinsic scatter and measurement noise relating these observables to their mean relations. We simultaneously fit for these astrophysical modeling parameters and for cosmology. Assuming a flat νΛCDM model, in which the sum of neutrino masses is a free parameter, we measure Ω m =0.276±0.047, σ 8 =0.781±0.037, and σ 8 (Ω m /0.3) 0.2 =0.766±0.025. The redshift evolutions of the X-ray Y X-mass and M gas-mass relations are both consistent with self-similar evolution to within 1σ. The mass slope of the Y X-mass relation shows a 2.3σ deviation from self-similarity. Similarly, the mass slope of the M gas-mass relation is steeper than self-similarity at the 2.5σ level. In a νwCDM cosmology, we measure the dark energy equation-of-state parameter w=−1.55±0.41 from the cluster data. We perform a measurement of the growth of structure since redshift z∼1.7 and find no evidence for tension with the prediction from general relativity. This is the first analysis of the SPT cluster sample that uses direct weak-lensing mass calibration and is a step toward using the much larger weak-lensing data set from DES. We provide updated redshift and mass estimates for the SPT sample.

The Three Hundred Project: Correcting for the hydrostatic-equilibrium mass bias in X-ray and SZ surveys

“…As such, they are optimal tracers of the growth of structures and useful tools for estimating cosmological parameters, such as those measuring the amount of matter, Ω M , and of dark energy, Ω Λ , and the normalization of the power spectrum of density fluctuations, σ 8 (see reviews by Voit 2005;Allen et al 2011;Kravtsov & Borgani 2012). Cosmological studies based on galaxy clusters essentially rely on the measurement of (i) the baryon fraction (Allen et al 2008;Ettori et al 2009;Mantz et al 2014), and (ii) the evolution of the cluster mass function, or the number density of clusters per unit mass and redshift interval (Vikhlinin et al 2009;Planck Collaboration et al 2014;Costanzi et al 2018;Bocquet et al 2019). The key quantity entering into both such techniques is the cluster mass.…”

Cosmology dependence of galaxy cluster scaling relations

“…Integrated observable properties of galaxy clusters like X-ray luminosity and temperature, the optical richness and their associated velocity dispersion, and the intensity of the Sunyaev-Zeldovich effect (SZE: Sunyaev & Zel'dovich 1972), are generally used as a proxy for the total cluster mass, as they are expected to regularly scale with galaxy cluster mass following mass-observable scaling relations (MOR), although with some associated intrinsic scatter. Current studies of the cluster mass function (often described as cluster number-counts experiments) are therefore simultaneously exploring both cosmological and MOR (including the intrinsic scatter) parameters to constrain cosmological models (e.g., Planck Collaboration et al 2016;Mantz et al 2015;Bocquet et al 2019). The standard approach for these stateof-the-art studies is to calibrate the MOR empirically, by anchoring the associated parameters through either weaklensing (e.g.…”

“…Therefore, for this reason, biases associated with weak lensing and dynamical estimates can be calibrated more robustly with numerical simulations. As a result, MOR parameters including the normalization, the mass slope, the redshift evolution, and the scatter, can be directly constrained from multi-wavelength observations (Mantz et al 2015;Dietrich et al 2019;Bocquet et al 2019). In most of these studies, the cosmological dependence of MORs is usually assumed to be only related to the background evolution of the Universe, with the notable exception of measurements of the baryon fraction in galaxy cluster to constraint the matter density (e.g., Mantz et al 2014).…”

“…We run the same simulation set-up for a sample of fifteen different flat ΛCDM cosmological models (C1, C2,..., C15). The cosmological parameters varied in each simulations are Ωm, σ8, h0, and Ω b and their values are specified in Table 1 and shown in Figure 1 as coloured points, together with cosmological constraints obtained by state-ofthe-art cluster number counts experiment (Bocquet et al 2019, with an additional Gaussian prior on h0 with mean 0.704 and width 0.014) . The parameter ranges used are thus 0.15 < Ωm < 0.45, 0.6 < σ8 < 0.9, and 0.65 < h0 < 0.75, to cover the entire dynamic range of current large-scalestructure cosmological constraints.…”

Mass Bias of Weak-lensing Shear-selected Galaxy Cluster Samples

“…The availability of clusters across a large redshift range kfchen@asiaa.sinica.edu.tw, b04901029@ntu.edu.tw allows us to obtain better constraints on dynamic parameters such as the dark energy equation of state compared to analyses relying on a single snapshot of the cosmic history (Weinberg et al 2013). Modern cluster cosmology constraints are usually derived from complex likelihood analyses (Vikhlinin et al 2009;Mantz et al 2010;Rozo et al 2010;Mantz et al 2014;Planck Collaboration et al 2016;de Haan et al 2016;Bocquet et al 2019), whose success relies heavily on one's ability to un-derstand the relations between halo masses and various observables from which cluster samples are selected.…”