a) Posterior probability distribution for log χ under the Gaussian density gradient model, M^G, for a period ratio of r = 3.0 and uncertainty given by σ = 0.2 (dashed); σ = 0.4 (solid); σ = 0.8 (dotted) and considering log χ ∈ [ 1,60 ] in the prior range. For σ = 0.4, the inferred median of the distribution is , with the uncertainty given at the 68% credible interval. b) Posterior probability distribution for χ under the Lorentzian density gradient model, M^L, for the same period ratio and uncertainty given by σ = 0.2 (dashed); σ = 0.4 (solid); σ = 0.8 (dotted) and considering χ ∈ [ 2,500 ] in the prior range. For σ = 0.4, the inferred median of the distribution is .