Zoom-in view of 2D map of the SFR resulting from Model A after 11 Gyr of the evolution of Fig. 3 compared with some tracers of spiral arms or arcs present in literature. Upper panel: overdensities in the distribution of UMS stars of the Poggio et al. (2018) sample with Gaia EDR3 astrometry (Gaia Collaboration 2021a) as presented by Poggio et al. (2021). We report only positive values of stellar overdensities as defined by Eq. (1) of Poggio et al. (2021). Middle panel: distribution of the median of the radial action J_R of Gaia DR3 stars (see text for more details) on the Galactic Plane (|Z_max|< 0.5 kpc and R < 10 kpc) as computed by Palicio et al. (2023b) and here only reporting the star with J_R < 0.01 R_⊙ V_⊙ (green shaded area). Lower panel: solid lines represent the segments of spiral arms traced by Cepheids of Lemasle et al. (2022) in which the colour coding is the one adopted by Palicio et al. (2023b).