Corner plot with the projection of the approximate posterior PDF obtained from the exploration of the six parameters of the thin disc component, including the IMF, the SFH, and the density laws. The vertical solid red lines and the vertical green dashed lines indicate the mode and the median for each parameter, respectively. For α₃, the median and the mode are superimposed. Green 2D contours and 1D distributions are for the distributions obtained directly from the ABC algorithm. The blue 1D posterior PDFs are built by accounting, in the posterior PDF, for the differences between BGM Std and BGM full simulations (see text). The vertical black dashed lines indicate the quantiles 0.16 and 0.84 of this distribution. On top of each 1D histogram the mode of the distribution and the interval of the 0.16 and 0.84 quantiles for the blue distributions are indicated. In black at the top right of each one of the 2D panels we show the Pearson’s correlation coefficient. The magenta cross indicates the parameters of the adopted Mother Simulation. γ is the inverse of the characteristic timescale when assuming an exponentially decreasing SFH. α₁, α₂ and α₃ are the slopes of the IMF assumed to be a three-times truncated power law with the mass limits fixed at x₁ = 0.5 M_⊙ and x₂ = 1.53 M_⊙. ρ_⊙ is the thin disc stellar volume mass density at the position of the Sun and h_R is the radial scale length of the thin-disc density profile assumed to be an Einasto shape (see units in Table 1). We obtain these results assuming the Drimmel & Spergel (2001) extinction map and using as observational data the stars in Tycho-2 catalogue with visual apparent magnitude V_T < 11.