Star Formation out of the Magnetised Interstellar Medium

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Magnetic fields are an elemental part of the interstellar medium (ISM) which have a large impact on the dynamics of the ISM on various spatial scales. One long-standing issue is their influence on the formation of stars in galaxies. Similarly to thermal pressure, magnetic fields prevent contraction of otherwise self-gravitating gas clumps if they are strong enough. Therefore, gaseous overdensities must be magnetically supercritical, quantified by the mass-to-flux ratio, to collapse and to subsequently allow the formation of stars. There is increasing evidence that the ISM-field is rather strong (B > 6 muG) which gives rise to the question how supercritical cloud cores can be generated? To answer this question is the goal of this project. Within this proposed project we will test the two possible answers to this issue, namely the ambipolar diffusion (AD) mediated process, where locally the mass-to-flux is increased and the accumulation process, where gas is gathered over large distances. Therefore, we will study in detail the physics which impacts the AD-model (e.g. chemical and radiative ionisation processes) and we will self-consistently probe the accumulation process with global galactic simulations.