Modeled normalized spherical harmonic coefficients C₂₀ (black dots) and C₂₂ (green dots) vs. the measured values by Yang et al. (2019) for the scenario where the mantle is denser than the core (the core shape is homothetic to the Phobos surface).The 1σ and 3σ error bars for the measured coefficients are the shaded and crossed bands. The different cases are shown along the y-axis: ρ_{_} c represents the density of the core, and represents the scaling size factor of the core. The scaling parameter λ varies from λ = 0 (no core) to λ = 1 (core boundary confounded with the surface). The dotted black line denotes the C₂₀ and C₂₂ values of the homogeneous case. The associated error bars are too small to be plotted two-layer modeled coefficients). The dotted red line denotes the measured C₂₀ and C₂₂ values with their associated 3σ formal errors (shaded red bands) and their associated 1σ formal errors (cross-hatched red bands). Triangle represent the layering cases that agree well with the C₂₀ from Yang et al. (2019). The normalized harmonic coefficients are computed with respect to a reference radius of 14 km. The cases marked by triangles are shown in Table 3.