Plasma environment of a weak comet – Predictions for Comet 67P/Churyumov–Gerasimenko from multifluid-MHD and Hybrid models

•We compare multifluid MHD and Hybrid models of the solar wind interaction with a weak comet.•The multifluid MHD results show a distinct improvement over previous single fluid simulations.•Multifluid MHD reproduces major features of the particle gyration as shown by the Hybrid model.•We identify a repetitive pattern of Mach cones along the cometary ion tail.•Both models show similar magnetic field draping and the formation of the anti-sunward tail. The interaction of a comet with the solar wind undergoes various stages as the comet’s activity varies along its orbit. For a comet like 67P/Churyumov–Gerasimenko, the target comet of ESA’s Rosetta mission, the various features include the formation of a Mach cone, the bow shock, and close to perihelion even a diamagnetic cavity. There are different approaches to simulate this complex interplay between the solar wind and the comet’s extended neutral gas coma which include magnetohydrodynamics (MHD) and hybrid-type models. The first treats the plasma as fluids (one fluid in basic single fluid MHD) and the latter treats the ions as individual particles under the influence of the local electric and magnetic fields. The electrons are treated as a charge-neutralizing fluid in both cases. Given the different approaches both models yield different results, in particular for a low production rate comet. In this paper we will show that these differences can be reduced when using a multifluid instead of a single-fluid MHD model and increase the resolution of the Hybrid model. We will show that some major features obtained with a hybrid type approach like the gyration of the cometary heavy ions and the formation of the Mach cone can be partially reproduced with the multifluid-type model.