Normalized torques felt by an1 M_⊕ planet with metallicities of ε = 0.01, 0.03, and 0.1. Three accretion efficiencies were modeled: η = 0, 0.1, and 1. The columns from left to right show three sets of models that assume different slopes for the initial disk density profile: p = 0.5, 1.0, and 1.5. Symbols represent the different Stokes numbers, St = 0.01, 0.1, 1, 2, 3, 4, 5, and 10. For the elevated metallicities, two models are shown: predicted (left) and numerical simulations (right). The shaded regions of positive (red), weakened negative (blue), and strengthened negative (green) torques darken with the metallicity. The normalization factor is the absolute value of the appropriate non-back-reacting gas torque. Panels A1, A2, and A3: Solid torques in the back-reacting models normalized by the absolute value of the solid torque non-back-reacting models with ε = 0.01. Panels B1, B2, and B3: Gas torques in the back-reacting models normalized by the absolute value of the gas torque in the non-back-reacting models with ε = 0.01. Panels C1, C2, and C3: Total torques in the back-reacting models normalized by the absolute value of the gas torque in the non-back-reacting models with ε = 0.01.