SIMBAD references

We investigate the extent to which the number of clusters of mass exceeding 10¹⁵ M_☉ h^–1 within the local super-volume (< 135 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 x 10^–3 (with σ₈ = 0.81) or 3.8 x 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.