  Context: High-spatial resolution Atacama Large Millimeter/submillimeter Array
(ALMA) data have revealed a plethora of substructures in protoplanetary disks.
Some of those features are thought to trace the formation of embedded planets.
One example is the gas and dust that accumulated in the co-orbital Lagrangian
regions $L_4$/$L_5$, which were tentatively detected in recent years and might
be the pristine material for the formation of Trojan bodies. Aims: This work is
part of the TROY project, whose ultimate goal is to find robust evidence of
exotrojan bodies and study their implications in the exoplanet field. Here, we
focus on the early stages of the formation of these bodies by inspecting the
iconic system PDS 70, the only confirmed planetary system in formation.
Methods: We reanalyzed archival high-angular resolution Band 7 ALMA
observations from PDS 70 by doing an independent imaging process to look for
emission in the Lagrangian regions of the two detected gas giant protoplanets,
PDS 70 b and c. We then projected the orbital paths and visually inspected
emission features at the regions around the $L_4$/$L_5$ locations as defined by
$\pm$ 60$^{\circ}$ in azimuth from the planet position. Results: We found
emission at a $\sim$4-$\sigma$ level ($\sim$6-$\sigma$ when correcting from a
cleaning effect) at the position of the $L_{5}$ region of PDS 70 b. This
emission corresponds to a dust mass in a range of 0.03- 2 M$_{Moon}$, which
potentially accumulated in this gravitational well. Conclusions: The tentative
detection of the co-orbital dust trap that we report requires additional
observations to be confirmed. We predict that we could detect the co-orbital
motion of PDS 70 b and the dust presumably associated with $L_5$ by observing
again with the same sensitivity and angular resolution as early as February
2026.
