Effective tidal dissipation factor Q_p of synthetic models of Jupiter (a, c) and Saturn (b, d) as a function of the viscoelastic parameters G and η: (a, b) use Eq. (1)and (c, d) use Eq. (20). The red dashed lines give the values of Lainey et al. (2009, 2012). The blue lines bound the region of the most likely rheological values (see text). We assume: R_p = { 10.97,9.14 } R_⊕ (R_⊕ is the Earth radius); M_p = { 317.8,95.16 } M_⊕.