Figure 2

Figure 2: Four trajectories in the (r,m ) plane. Each trajectory corresponds to the models: (i) ΛCDM, (ii) f(R) = (Rb − Λ)c, (iii) f (R) = R − αRn with α > 0,0 < n < 1, and (iv) 2 m (r) = − C (r + 1)(r + ar + b). From [31].