Quantifying the rarity of the local super-volume

• Published in: Monthly notices of the Royal Astronomical Society Vol. 507; no. 4; pp. 5425 - 5431
• Main Authors: Stopyra, Stephen, Peiris, Hiranya V, Pontzen, Andrew, Jasche, Jens, Natarajan, Priyamvada
• Format: Journal Article
• Language: English
• Published: Oxford University Press 01-11-2021
• Subjects: cosmology: theory; large-scale structure of Universe; methods: data analysis; methods: data analysis; large-scale structure of Universe; cosmology: theory
• ISSN: 0035-8711; 1365-2966; 1365-2966
• DOI: 10.1093/mnras/stab2456

ABSTRACT
We investigate the extent to which the number of clusters of mass exceeding $10^{15}\, M_{\odot }\, h^{-1}$ within the local super-volume ($\lt 135\mathrm{\, Mpc\, }h^{-1}$) is compatible with the standard ΛCDM cosmological model. Depending on the mass estimator used, we find that the observed number N of such massive structures can vary between 0 and 5. Adopting N = 5 yields ΛCDM likelihoods as low as 2.4 × 10−3 (with σ8 = 0.81) or 3.8 × 10−5 (with σ8 = 0.74). However, at the other extreme (N = 0), the likelihood is of order unity. Thus, while potentially very powerful, this method is currently limited by systematic uncertainties in cluster mass estimates. This motivates efforts to reduce these systematics with additional observations and improved modelling.