Constraining Cosmology using Galaxy Clusters

Reviews

Allen2011

Allen2011

  • Cosmological Parameters from Observations of Galaxy Clusters - ARA&A review by Allen, Evrard & Mantz 2011
  • Huterer et al. 2015 - Growth of cosmic structure: Probing dark energy beyond expansion
    • See Section 4.2: Cluster Abundance
    • The primary importance of clusters in the context of dark energy is their complementarity to geometric probes, i.e. their ability to distinguish between modified gravity and dark energy models with degenerate expansion histories. Galaxy clusters are statistically competitive with and often better than other probes. (Fig 5, right panel, the “sweet spot” is z=0.3 - 0.8.
    • The basic physics behind cluster abundances as a cosmological probe are conceptually simple; and A cluster abundance experiment is conceptually very simple.
    • The dependence of the number of galaxy clusters on the variance of the linear density field that allows us to utilize galaxy clusters to constrain the growth of structure.
    • Future surveys will almost certainly rely on weak lensing mass calibration to estimate cluster masses.
    • Other usages of clusters as a cosmological tool:
      • Galaxy clusters can probe dark energy in other ways as well, most notably by comparing cluster mass estimates from weak lensing and dynamical methods such as galaxy velocity dispersions
      • Because the growth of structure is also impacted by non-zero neutrino mass, galaxy cluster abundances can provide competitive constraints on the sum of neutrino masses.
    • Difficulties and limitations:
      • To achieve the goal of DES Stage III (IV) requirement, we must be able to measure cluster masses with 5% (2%) precision. See Applegate et al. (2014) (Currently can achieve 7%, but with 20% systematic differences among methods).
      • Systematic errors in shear measurements tend to be less critical for cluster abundance work than for cosmic shear work (only care about circular averaged tangential shear).
      • Key systematic is the calibration not only of the mean relation between cluster observables (optical, X-ray, or mm signals) and cluster mass, but also the scatter (shape and amplitude) about the mean.
      • Cluster centering remains an important systematic in optical and/or low resolution experiments (e.g. Planck). (See Oguri & Takada 2011 about self-calibration).
      • Optical observations benefit from a lower mass detection threshold than X-ray/mm over a large redshift range, which in turn result in improved statistical constraints.
      • The synergistic nature of multi-wavelength cluster cosmology will necessarily play a key role in future cluster abundance experiments. A balanced multi-wavelength approach will be critical to the success of cluster cosmology over the next 10–20 years.
      • Self-calibration: the cluster-clustering signal is itself an observable that one can use to calibrate cluster masses, and which is insensitive to all of the above systematic effects.
  • Huterer & Shafer 2018 - Dark energy two decades after: observables, probes, consistency tests
    • See Section 5.5 Galaxy Clusters
    • Clusters are versatile probes of cosmology and astrophysics and have had an important role in the development of modern cosmology
    • Recent cluster observations typically do not have enough signal-to-noise to determine the cluster masses directly; instead, forward-modeling can be applied to the mass function to recast the theory in the space of observable quantities (e.g. see Evrard et al. 2014).
    • The mass function’s near-exponential dependence on the power spectrum in the high-mass limit is at the root of the power of clusters to probe the growth of density fluctuations.
    • (The clusters’) two-point correlation function probes the matter power spectrum as well as the growth and geometry factors sensitive to dark energy.
    • Clusters can also be correlated with background galaxies to probe the growth (Cluster-Galaxy lensing, see Oguri & Takada 2011
    • The most important uncertainty is typically tied to parameters that describe the scaling relations between mass and observable properties of the cluster (e.g. Flux, temperature).
  • Weinberg 2013, PhR - Observational probes of cosmic acceleration
    • See Section 6: Clusters of galaxies

Key Papers

Theoretical

Predictions

Systematic, (Self-)Calibration

Observational

Cluster mass calibration and scaling relations

Lectures and Conferences

Important References

  • Galaxy clusters have been recognized as powerful cosmological probes
    • Henry et al. 2009; Vikhlinin et al. 2009; Mantz et al. 2010; Rozo et al. 2010; Clerc et al. 2012; Benson et al. 2013; Hasselfield et al. 2013).
  • Early optical cluster finders can be divided into roughly two classes
    1. Those based on photometric redshifts
      • Kepner et al. 1999; van Breukelen & Clewley 2009; Milkeraitis et al. 2010; Durret et al. 2011; Szabo et al. 2011; Soares-Santos et al. 2011; Wen et al. 2012
    2. Those utilizing the cluster red sequence
      • Annis et al. 1999; Gladders & Yee 2000; Koester et al. 2007a; Gladders et al. 2007; Gal et al. 2009; Thanjavur et al. 2009; Hao et al. 2010; Murphy et al. 2012