Left: dynamical selection of the GSE sample in the ﹩\sqrt{{J}_{r}}﹩–L_z plane. The red box marks the adopted selection region, defined by ﹩30\,\leqslant \,\sqrt{{J}_{r}}\,\leqslant \,55﹩ (kpc km s⁻¹)^1/2 and −500 ≤ L_z ≤ 500 kpc km s⁻¹. Right: KDE-smoothed age distributions of the thick-disk, Splash, and GSE samples, with stellar age uncertainties taken into account. The peak ages of the thick-disk, Splash, and GSE populations are 11.59, 11.86, and 11.92 Gyr, respectively.