Constraining the evolution of dark energy with a combination of galaxy cluster observables

Abstract

We show that the abundance and redshift distribution (dN/dz) of galaxy clusters in future highyield cluster surveys, combined with the spatial power spectrum (Pc(k)) of the same clusters, can place significant constraints on the evolution of the dark energy equation of state, w = w(a). We evaluate the expected errors on wa = −dw/da and other cosmological parameters using a Fisher matrix approach, and simultaneously including cluster structure evolution parameters in our analysis. We study three different types of forthcoming surveys that will identify clusters based on their X-ray emission (such as DUO, the Dark Universe Observatory), their Sunyaev-Zel'dovich (SZ) decrement (such as SPT, the South Pole Telescope), or their weak lensing (WL) shear (such as LSST, the Large Synoptic Survey Telescope). We find that combining the cluster abundance and power spectrum significantly enhances constraints from either method alone. We show that the weak-lensing survey can deliver a constraint as tight as ∆wa ∼ 0.1 on the evolution of the dark energy equation of state, and that the X-ray and SZ surveys each yield ∆wa ∼ 0.4 separately, or ∆wa ∼ 0.2 when these two surveys are combined. For the X-ray and SZ surveys, constraints on dark energy parameters are improved by a factor of two by combining the cluster data with cosmic microwave background (CMB) anisotropy measurements by Planck, but degrade by a factor of two if the survey is required to solve simultaneously for cosmological and cluster structure evolution parameters. The constraint on wa from the weak lensing survey is improved by ∼ 25% with the addition of Planck data.

Constraining thawing and freezing models with cluster number counts

“…Here ζ(z) = (ρ cl /ρ b )| x=1 corresponds to the overdensity at turn-around time t. We determine ζ(z) by solving (8) and (9) simultaneously using the boundary conditions dy/dx| x=1 = 0, y| x=1 = 1 and y| x=0 = 0. Once ζ is known, we can evaluate the linear density contrast at the time of collapse point δ c as a function of redshift using (8), (9) and the linear growth factor, D(z):…”

“…In this regard, measurements of the cluster abundance as a function of mass and redshift are coming up with the potential to improve current constraints on cosmological parameters [9,10], including the dark energy EoS, the rms mass fluctuations, the matter density parameter, the total neutrino masses, etc. These data have the advantage of probing both the expansion rate and the growth of perturbations, thereby being complementary to other cosmological probes such as the Comic Microwave background (CMB) anisotropies, observations of type Ia supernovae and measurements of baryon acoustic oscillations (BAO).…”

Effects of shear and rotation on the spherical collapse model for clustering dark energy

“…The latest observations of Supernovae type Ia (Riess et al 1998;Perlmutter et al 1999;Knop et al 2003;Riess et al 2004;Astier et al 2006;Riess et al 2007;Amanullah et al 2010), together with the cosmic microwave ⋆ E-mail: Francesco.Pace@port.ac.uk background (CMB) Jarosik et al 2011;Planck Collaboration et al 2013a,b,c;Sievers et al 2013), the integrated Sachs-Wolfe effect (ISW) (Giannantonio et al 2008;Ho et al 2008), the large scale structure (LSS) and baryonic acoustic oscillations (Tegmark et al 2004a,b;Cole et al 2005;Eisenstein et al 2005;Percival et al 2010;Reid et al 2010;Blake et al 2011), the globular clusters (Krauss & Chaboyer 2003;Dotter et al 2011), high redshift galaxies (Alcaniz et al 2003) and the galaxy clusters (Haiman et al 2001;Allen et al 2004Allen et al , 2008Wang et al 2004;Basilakos et al 2010) till works based on weak gravitational lensing (Hoekstra et al 2006;Jarvis et al 2006) and X-ray clusters (Vikhlinin et al 2009) confirmed these early findings and they are all in agreement with a universe filled with 30% by cold dark matter and baryons (both fluids pressureless) and with the remaining 70% by the cosmological constant Λ (the so-called ΛCDM model). The cosmological constant is the most basic form of dark energy.…”

The dark matter distribution inz ~ 0.5 clusters of galaxies

“…The observed cluster abundance, converted into a mass function, can be compared to cosmological numerical simulations to put tight constraints on cosmological parameters, such as the amplitude of matter fluctuations or the dark energy density (Bahcall & Cen 1992;White et al 1993;Haiman et al 2001;Wang et al 2004;Albrecht et al 2006;Mandelbaum & Seljak 2007;Rozo et al 2009). The main limitation in the use of this mass function is the practical determination of the masses themselves.…”