GRB 090510 broadband modeling in the synchrotron ES scenario. Data are taken from the light curves in Figure 1 of De Pasquale et al. (2010), where the mean flux measured in each energy range for the different instruments ( Fermi/LAT, Swift/XRT, and Swift/UVOT) has been rescaled to give the measured flux at each specific frequency (1 GeV, 1 keV, and 10 ¹⁵ Hz). This is done by requiring at 100 s the specific flux value reported in the SED plotted in Figure 2 of De Pasquale et al. (2010). The black, red, and purple solid lines represent the model predictions at 1 GeV, 1 keV, and 10 ¹⁵ Hz, respectively. Parameters are set as follows—for the narrow and wide jet components (dash-dotted lines), respectively: _e = 0.1, _B = 3 × 10 ⁻³, n = 10 ⁻⁶, Γ _{0, n} = 10 ⁴, E _iso,n = 3.7 × 10 ⁵³ erg, p _n = 2.3, θ _{j, n} = 0 12, Γ _{0, w} = 220, E _iso,w = 1.5 × 10 ⁵³ erg, p _w = 2.5, and θ _{j, w} = 0 43. The blue lines represent the contribution of the narrow and wide jet components at the middle of the BAT energy band; throughout the evolution this is below the data/upper-limits reported in De Pasquale et al. (2010), in agreement with our hypothesis that the emission observed in the GBM/BAT/MCAL energy range should be due to IS rather than to ES.