Different stages applied to preselect the data. Left column: stellar density maps in the l-b plane; Right column: stellar density maps in the transverse velocity plane. The color bars show the color coding of point-source density in log-scale. Row 1: all the candidates downloaded from the Gaia Archive. Row 2: after applying the filter of RUWE < 1.4 and (σ_ϖ/ϖ) < 0.2. Row 3: in addition to the previous filters, apply all the conditions in the first table of Table 2. Row 4: in addition to the previous cuts, apply all the conditions in the second and third table in Table 2. This set contains the preselected candidates.