Methods for cluster cosmology and application to the SDSS in preparation for DES Year 1 release

Abstract

We implement the first blind analysis of cluster abundance data to derive cosmological constraints from the abundance and weak lensing signal of redMaPPer clusters in the Sloan Digital Sky Survey (SDSS). We simultaneously fit for cosmological parameters and the richness-mass relation of the clusters. For a flat cold dark matter cosmological model with massive neutrinos, we find S 8 ≡ σ 8 ( m /0.3) 0.5 = 0.79 +0.05 −0.04 . This value is both consistent and competitive with that derived from cluster catalogues selected in different wavelengths. Our result is also consistent with the combined probes analyses by the Dark Energy Survey (DES), the Kilo-Degree Survey (KiDS), and with the cosmic microwave background (CMB) anisotropies as measured by Planck. We demonstrate that the cosmological posteriors are robust against variation of the richness-mass relation model and to systematics associated with the calibration of the selection function. In combination with baryon acoustic oscillation data and big bang nucleosynthesis data (Cooke et al.), we constrain the Hubble rate to be h = 0.66 ± 0.02, independent of the CMB. Future work aimed at improving our understanding of the scatter of the richness-mass relation has the potential to significantly improve the precision of our cosmological posteriors. The methods described in this work were developed for use

Aging haloes: implications of the magnitude gap on conditional statistics of stellar and gas properties of massive haloes

“…Developing an accurate and precise halo mass estimator is an essential step in constraining the cosmological parameters with galaxy clusters. While cluster observable variance is studied extensively in the literature, it is one of the least constrained quantities and a source of systematic in a cluster cosmology analysis (Farahi et al 2019b;Costanzi et al 2019b). Therefore, identifying and incorporating observables which can reduce the scatter in mass-observable relation is of particular interest.…”

“…With optical-surveys, optical-richness (Rykoff et al 2016;Farahi et al 2019b) and total stellar mass (Palmese et al 2019) have emerged as a potential low scatter proxy of halo mass to perform cosmological analysis (Costanzi et al 2019b). The statistical parametric models, such as the linear model employed here, are readily applicable to observational data, and the parameters can be inferred directly from the data (McClintock et al 2019).…”

“…Reducing the scatter does not only clue in on galaxy formation and astrophysics but also has an impact on the cosmological parameters estimation. This scatter parameter controls how accurately the mass of these systems can be estimated given a set of properties and governs the accuracy of a cosmological analysis (Costanzi et al 2019b;Farahi et al 2019b). Additionally, reducing the scatter can lessen the impact of systematics -such as selection bias and non-Gaussianity in the mass-observable relation -on a cosmological analysis.…”

Stellar property statistics of massive haloes from cosmological hydrodynamics simulations: common kernel shapes

“…Forward modeling counts of massive halos as a function of an observable property, s, is sensitive to the assumed shape of the conditional kernel, p(s | M, z) (e.g., Shaw et al 2010;Erickson et al 2011;Costanzi et al 2019). Moving beyond the mild tensions in stellar property variance seen above, we seek here to test whether consistent kernel shapes emerge from the different simulation treatments.…”

Cosmology dependence of galaxy cluster scaling relations

“…The parameter space θ is explored with affine invariant sampler emcee (Foreman-Mackey et al 2013). We refer the reader to Costanzi et al (2019) for further details on the likelihood and covariance matrix calculation.…”