Delivery of organic matter to the Galilean moons

The presence of carbonaceous matter is envisaged on the surface of many outer solar system bodies, including the Galilean moons. Density and moments of inertia of icy moons and dwarf planets also suggest the presence of this material in their refractory cores. The initial carbonaceous matter would have been composed of complex organic molecules (COMs) that possibly formed when the building blocks of the moons were in the forms of pebbles and icy grains in the protosolar nebula. Experimental studies indeed show that COMs can be formed from the UV irradiation of icy grains under nebular conditions.

A baseline scenario is the formation of the Galilean moons in a circumplanetary disk that was too cold to vaporize the solids originating from the protosolar nebula. In this scenario, only the thermodynamic conditions of the protosolar nebula play a crucial role in determining the composition of the building blocks of the moons. Here we aim to assess the thermodynamic conditions of the protosolar nebula that enable the formation and the delivery of COMs to the formation location of the Galilean moons in the context of the aforementioned scenario. To do so, we have developed a two-dimensional model that describes the transport of pebbles/dust particles during the evolution of the protosolar nebula, using a Lagrangian scheme. This allows us to calculate the interstellar flux received by the particles as they migrate through the nebula.