Delivery of complex organic molecules to the system of Jupiter

ABSTRACT Complex organic molecules are key markers of molecular diversity, and their formation conditions in protoplanetary discs remain an active area of research. These molecules have been detected on a variety of celestial bodies, including icy moons, and may play a crucial role in shaping the current composition of the Galilean moons. Experimental studies suggest that their formation could result from ultraviolet (UV) irradiation or thermal processing of NH$_3$:CO$_2$ ices. In this context, we investigate the formation of complex organic molecules in the protosolar nebula and their subsequent transport to the Jupiter system region. Lagrangian transport and irradiation simulations of 500 individual particles are performed using a two-dimensional disc evolution model. Based on experiments with UV irradiation and thermal processing of CO$_2$:NH$_3$ ice, this model allows us to estimate the estimate the potential for the formation of complex organic molecules through these processes. Almost none of the particles released at a local temperature of 20 K (corresponding to $\sim$12 au from the Sun) reach the location of the system of Jupiter. However, when released at a local temperature of 80 K ($\sim$7 au), approximately 45 per cent of the centimetric particles and 30 per cent of the micrometric particles can form complex organic molecules via thermal processing, subsequently reaching the location of the system of Jupiter within 300 kyr. Assuming that the Galilean moons formed in a cold circumplanetary disc around Jupiter, the nitrogen-bearing species potentially present in their interiors could have originated from the formation of complex organic molecules in the protosolar nebula.