Dynamical map around the L₄ point on the (a₀, i₀) plane. The colour indicates the SN of cosσ, which is shown on a base-10 logarithmic scale for more details. The orbits that escape from the Earth co-orbital region (see text) during the integration time (12 Myr) are excluded. The dashed lines indicate the separatrices between the tadpole and horseshoe orbits (see text in Sect. 4.2), which divide the dynamical map into three regimes. The tadpole orbits reside in the central region (denoted by “C”) while the horseshoe orbits are found in the left (“L”) and right (“R”) regions.