Since the discovery of the first exoplanet, a gaseous giant planet, two decades of an extensive planet hunt led to an amazing inventory of close-by planet systems. Among these planets a substantial number are slightly larger than Earth but are still expected to be rocky. No similar object exists in the solar system and little is known about them. One interesting aspect is to determine the habitability of these exotic planets and if life could develop there. It is therefore important to determine what is the structure of the deep interior of these planets and if it can generate a protecting magnetic field. In the proposed project, the fellow plans to develop a set of state-of-the-art ab initio simulations of iron-nickel mixtures to study the properties of these materials at high pressure. These materials are likely to be dominant in the core of Super-Earth but it is unclear if the pressure-temperature conditions are compatible with a solid core surrounded by a liquid and conducting phase as expected to be favorable for magnetic field generation. The fellow will focus on the phase diagram of these mixtures up to 1 TPa. He will also explore the transport properties in order to better constrain the possible scenarios of convection and magnetic field generation. Based on these results, the fellow will build evolution models of Super-Earths to be compared to the discovered exoplanets.

The ice giant planets Uranus and Neptune are believed to play a crucial role in the formation process of our Solar System and are prototypical for hundreds of exoplanets, so-called mini-Neptunes, which are discovered at ever increasing speed thanks to planet-hunting missions like Kepler, TESS, and PLATO. Modeling the interior structure, magnetic dynamo, and thermal evolution of Uranus and Neptune has proven very challenging relying only on the Voyager 2 flyby data from the 1980s and ground-based observations. The key to improve these models is to investigate interfaces and thermal boundaries resulting from the properties of the material in their deep interiors. Hence, we perform molecular dynamics simulations on multiple scales to derive additional modeling constraints, which are experimentally challenging to obtain or even inaccessible. We use accurate ab initio simulations to calculate a new equation of state to constrain the rock/ice ratio in planetary interior models. Subsequently, we fit potentials to the ab initio data to investigate up to 1 million atoms using classical molecular dynamics. For the first time, we are able to explore interfaces between the inner mantle and the core of an ice giant planet on a atomic level. The resulting thermal and transport properties will be used as essential inputs for novel interior structure and magnetic dynamo models for ice giant planets; particularly those in our Solar System. The project results will enhance the fellow's career prospects, make a significant contribution to the science excellence in Europe, and especially strengthen the science case for future Uranus and Neptune missions by ESA and NASA.

Active-matter physics describes the mesmerizing dynamics of interacting motile bodies: from bird flocks and cell colonies, to collections of synthetic units independently driven far from equilibrium. Until now, however, all man-made realizations have been merely limited to 2D model systems. We will introduce a paradigm shift to upgrade the status of synthetic active matter from aesthetic 2D experiments to genuine 3D materials with unanticipated engineering applications. The essential goal is to construct the first generation three-dimensional active materials assembled from colloidal spinners, and to lay out the foundations of spinning active matter. I articulate my project around three complementary aims, all based on a unique experimental platform combining high-content microfluidics, smart colloidal design, optical tweezers, and high-speed confocal imaging: Aim 1. Spinner Interactions. We will introduce a versatile microfluidic platform to disentangle, tailor and elucidate the pair interactions which dictate the collective dynamics of colloidal spinners. Aim 2. Frustration-induced (dis)order. Building first on model experiments on spinning monolayers, we will explain how the intrinsic frustration of spinning motion at the microscopic scale shapes the macroscopic structure and flows of spinning matter. Aim 3. Spinner liquids, solids and liquid crystals. We will then be equipped to introduce the first generation of tree dimensionnal liquids, solids and liquid crystals assembled from synthetic active matter. Combining microfluidics and high-speed confocal imaging, we will establish their phase behavior and relate their inner microscopic dynamics to their macroscopic mechanical response.

The Late Devonian (380 to 360 Myr ago) is marked by the apogee of the terrestrialisation process that consists in the establishment of complex continental ecosystems. After the invasion of land by plants, and by arthropods, it is the rise of tetrapods (four-legged vertebrates) at the end of the Devonian that will change Earth’s continental ecosystems forever. Their complete terrestrialisation is only recorded by the Carboniferous and the Late Devonian represents thus the ideal period to understand processes related to tetrapod terrestrialisation. While the taxonomic richness, the phylogenetic relationships and the paleoenvironmental settings of Devonian tetrapods are better understood yet, a serious gap remains in our knowledge of the palaeoecological context. This is a major evolutionary issue, as tetrapods obviously did not evolve in an ecological vacuum and faunal interactions must have been critical driving forces for the transition from water to land. To tackle these issues, the ‘Trophic Networks at the dawn of tetrapod Terrestrialisation’ (TNT) project focuses on the trophic relationships in eight crucial and diverse Devonian vertebrate assemblages containing tetrapods. It blends calcium isotope analyses with statistical analyses of ecomorphological characters to reconstruct the trophic position, trophic interactions, and paleoecology of Late Devonian vertebrates under different environments and climates. Because Recent trophic networks provide a comparative basis for understanding Past ecosystems, two Recent localities, with fossil analogues, are also studied in the scope of the TNT project. The TNT project aims to estimate the predation pressures exerted on tetrapods and if these pressures acted as a driving force for their terrestrialisation.

One of the most fascinating and challenging question of Modern Astrophysics is: How do planets form? Indeed, micronic dust grains must grow over 30 orders of magnitude in mass to build planet cores. Global numerical simulations of dust grains that couple the dynamics of the particles to their growth/fragmentation and the radiation in the disc are compulsory to understand this process. Yet, this coupling has never been realised, given tremendous difficulties that originate from fundamental physical properties of dusty flows. The evolution of the dust distribution in protoplanetary discs remains therefore very poorly understood. Our novel groundbreaking code is the first to handle non-ideal MHD, radiation and dust with dynamical growth and fragmentation. We can therefore overcome all past difficulties to model gasgrains mixtures in discs consistently. PODCAST is designed to study the different stages of gas and dust evolution in the various regions of the disc, with the main objective of combining these steps in a holistic model for planet formation. We will confront the results directly with observations, unleashing the full potential of the grand instruments ALMA, SPHERE, JWST and SKA.