Marginal posteriors for panels aα and bG for different values of the damping ratio r = τ_d/P obtained by inversion of Eqs. (16) and (13) and by considering them as additional parameters together with ζ and l/R. In panel a the vertical dashed lines indicate the values α = 1 (linear density model) and α = π/2 (sinusoidal density model). The mean and error at 68% credible intervals for the posteriors in panel a are: for r = 2; for r = 3; for r = 4; and for r = 5. The mean and error at 68% credible intervals for the posteriors in panel b are: for r = 2; for r = 3; for r = 4; and for r = 5. In all computations the error in damping ratio is fixed to σ = 0.2.