Collisional evolution of Jupiter trojans after capture: Insights into their origin and cratering record

¹ Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal, Escuela Politécnica Superior, Universidad de Alicante, 03690 Sant Vicent del Raspeig (Alicante), Spain
² Instituto de Física Aplicada a las Ciencias y la Tecnologías, Universidad de Alicante, 03690 Sant Vicent del Raspeig (Alicante), Spain
³ Faculdade de Ciências e Tecnologias, Universidade de Coimbra, Portugal
⁴ Institut de Ciències del Cosmos (ICCUB), Universitat de Barcelona (IEEC-UB), Carrer de Martí i Franquès, 1, 08028 Barcelona, Spain

^★ Corresponding author: paula.benavidez@ua.es

Received: 1 March 2025
Accepted: 1 July 2025

Abstract

Context. Jupiter trojans (JTs) are asteroids that populate the Sun–Jupiter Lagrangian regions L4 and L5. This population is believed to be made up of leftovers from the Solar System’s early days that have remained in stable orbits around Jupiter for billions of years after their capture.

Aims. We investigated the long-term collisional evolution and the expected cratering record of the JT population under different initial conditions to assess whether these results are compatible with setting its origin in the primordial outer planetesimal disk.

Methods. We developed a dedicated numerical tool for this study by adapting the ALICANDEP code package, originally designed for trans-Neptunian objects, to the specific dynamical and physical environment of JTs. We also implemented updated scaling laws in the fragmentation algorithm to better capture the parameters dependency governing collisional physics. We validated the resulting model by comparing the output with previous results reported in the literature.

Results. Our findings support the hypothesis that JT formed in the primordial outer belt before being captured by Jupiter during the instability of the giant planets. The cratering record study demonstrates that material properties and cratering scaling law parameters can strongly influence the modelled crater distribution, with variations in strength and porosity affecting the saturation levels and crater sizes. This study provides insights into the collisional history of JTs and offers predictions for interpreting cratering data from the Lucy mission (NASA).