Collot, CCCollotGhoul, TETEGhoulMasmoudi, NNMasmoudiVan Tien Nguyen2022-12-212022-12-212022-070010-3640https://scholars.lib.ntu.edu.tw/handle/123456789/626701We construct solutions to the two-dimensional parabolic-elliptic Keller-Segel model for chemotaxis that blow up in finite time T. The solution is decomposed as the sum of a stationary state concentrated at scale λ and of a perturbation. We rely on a detailed spectral analysis for the linearised dynamics in the parabolic neighbourhood of the singularity performed by the authors in [10], providing a refined expansion of the perturbation. Our main result is the construction of a stable dynamics in the full nonradial setting for which the stationary state collapses with the universal law. (Formula presented.). where γ is the Euler constant. This improves on the earlier result by Raphael and Schweyer and gives a new robust approach to so-called type II singularities for critical parabolic problems. A by-product of the spectral analysis we developed is the existence of unstable blowup dynamics with speed. (Formula presented.) © 2021 Wiley Periodicals LLC.II BLOW-UP; RADIALLY SYMMETRIC-SOLUTIONS; CHEMOTAXIS MODEL; POINT DYNAMICS; CRITICAL MASS; AGGREGATION; 8-PI-PROBLEM; MECHANISMS; LIMITjournal article10.1002/cpa.219882-s2.0-85103194687WOS:000632473300001https://api.elsevier.com/content/abstract/scopus_id/85103194687