Evolution of the Magellanic System

Understanding interacting galaxies is among the key issues of modern astrophysics. Related to cosmological structure formation galaxy interactions and hierarchical merging cover large-scale dynamics, the dark matter distribution or various aspects of baryonic physics (like star formation, stellar feedback or the physics of the multi- phase interstellar medium). Nearby encounters provide an ideal laboratory to study these processes in detail. In combination with numerical simulations they allow a deeper insight into extragalactic physics and they are an excellent test bed for state-of-the-art theoretical/numerical models. The Magellanic System (MS) composed of the Large Magellanic Cloud (LMC), the Small Magellanic Cloud (SMC) and the extended - mainly gaseous - structures around them (the Magellanic Stream, the Interface Region and the Leading Arm) constitute such an ideal test bed: they are the nearest, but still individually well-defined interacting galaxies. Their proximity allows for a highly resolved, multi-wavelength view not available for any other galaxy (except the MW). These data include information about the kinematics, the star formation history, the chemistry or the interstellar medium of both Clouds and the associated structures. Proper motion measurements give constraints on their orbital motions which will be refined even more with the European GAIA mission launched soon. Though there is a wealth of information available there are still many open questions about the Magellanic System like the orbital history of the Clouds (are they bound to each other, to the MW?), the origin of the Magellanic Stream (induced by gravitational tides, by ram pressure or by alternative processes?), the age of the extended HI structures, the reason for the different star formation histories in LMC and SMC or the dark matter content of LMC and SMC among others. In our project we have the ambitious goal to create a state-of-the-art model for the Magellanic System. In the first subproject (PostDoc) we want to investigate the dynamics and the gross properties of the Magellanic Clouds by a detailed comparison with observational (mainly HI) data. Due to the high computational costs (extended parameter space; expensive self-consistent N-body/gas dynamics simulations) we adopt a two-step modelling approach: in the first step we extend our existing genetic algorithm (GA) based analysis of the Magellanic System`s parameter space for a more realistic physical description focussing on ram pressure and the dark matter halos of LMC/SMC. These models are based on computationally fast, but approximative restricted N-body calculations. In the second step we study and refine the preferred scenario(s) by detailed N-body/gas dynamical simulations. Physically, these models are superior to the GA models, because they include the stellar dynamics (e.g. the dynamical friction) and the ram pressure self-consistently. In the second subproject (PhD) we focus on the evolution of the interstellar medium in the Magellanic Clouds as well as on their star formation history. The calculation will be done with the galactic evolution code developed by the Vienna group. This code includes a multi-phase ISM treatment as well as star formation and stellar feedback. We want to address questions about the distribution of the different ISM components, the star formation history of the Clouds, their relation to the orbital history and the chemistry of the Magellanic System. Starting point will be reference models from the literature as well as the model classes found in our recently published GA based analysis. Later on models from the first subproject will be studied.

Understanding interacting galaxies is among the key issues of modern astrophysics. Related to cosmological structure formation galaxy interactions and hierarchical merging cover large-scale dynamics, the dark matter distribution or various aspects of baryonic physics (like star formation, stellar feedback or the physics of the multi- phase interstellar medium). Nearby encounters provide an ideal laboratory to study these processes in detail. In combination with numerical simulations they allow a deeper insight into extragalactic physics and they are an excellent test bed for state-of-the-art theoretical/numerical models. The Magellanic System (MS) composed of the Large Magellanic Cloud (LMC), the Small Magellanic Cloud (SMC) and the extended - mainly gaseous - structures around them (the Magellanic Stream, the Interface Region and the Leading Arm) constitute such an ideal test bed: they are the nearest, but still individually well-defined interacting galaxies. Their proximity allows for a highly resolved, multi-wavelength view not available for any other galaxy (except the MW). These data include information about the kinematics, the star formation history, the chemistry or the interstellar medium of both Clouds and the associated structures. Proper motion measurements give constraints on their orbital motions which will be refined even more with the European GAIA mission launched soon. Though there is a wealth of information available there are still many open questions about the Magellanic System like the orbital history of the Clouds (are they bound to each other, to the MW?), the origin of the Magellanic Stream (induced by gravitational tides, by ram pressure or by alternative processes?), the age of the extended HI structures, the reason for the different star formation histories in LMC and SMC or the dark matter content of LMC and SMC among others. In our project we have the ambitious goal to create a state-of-the-art model for the Magellanic System. In the first subproject (PostDoc) we want to investigate the dynamics and the gross properties of the Magellanic Clouds by a detailed comparison with observational (mainly HI) data. Due to the high computational costs (extended parameter space; expensive self-consistent N-body/gas dynamics simulations) we adopt a two-step modelling approach: in the first step we extend our existing genetic algorithm (GA) based analysis of the Magellanic System`s parameter space for a more realistic physical description focussing on ram pressure and the dark matter halos of LMC/SMC. These models are based on computationally fast, but approximative restricted N-body calculations. In the second step we study and refine the preferred scenario(s) by detailed N-body/gas dynamical simulations. Physically, these models are superior to the GA models, because they include the stellar dynamics (e.g. the dynamical friction) and the ram pressure self-consistently. In the second subproject (PhD) we focus on the evolution of the interstellar medium in the Magellanic Clouds as well as on their star formation history. The calculation will be done with the galactic evolution code developed by the Vienna group. This code includes a multi-phase ISM treatment as well as star formation and stellar feedback. We want to address questions about the distribution of the different ISM components, the star formation history of the Clouds, their relation to the orbital history and the chemistry of the Magellanic System. Starting point will be reference models from the literature as well as the model classes found in our recently published GA based analysis. Later on models from the first subproject will be studied.