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BP: Fachverband Biologische Physik

BP 19: Cell Mechanics 2

BP 19.7: Vortrag

Mittwoch, 7. September 2022, 16:45–17:00, H16

Condensed topological defects in compressible active nematics — •Ivan Maryshev¹, Timo Krüger¹, and Erwin Frey^1,2 — ¹LMU, München, Germany — ²Max Planck School Matter to Life, München, Germany

So far, topological defects with plus/minus 1/2 charges have been considered to be characteristic features of homogeneous active nematics. Phase-separated systems, in turn, have been known for the formation of dense nematic bands. Here, we use the agent-based model for weakly-aligning self-propelled filaments and, for the first time, demonstrate that phase-separated active nematics form -1/2 defects of a new kind. In contrast to the homogeneous case, these new defects correspond to high-density regions and coexist with bending bands. We also observe filamentous arc ejections - formations of lateral arcuate structures that separate from the band's bulk and move in a transverse direction. We show that the key control parameters defining the transition from the topologically charged structures to stable bands are the initial density of particles and their path persistence length. Finally, we develop hydrodynamic theory recapitulating observed phenomena.